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aria-controls="toc-Specifications-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Specifications subsection</span> </button> <ul id="toc-Specifications-sublist" class="vector-toc-list"> <li id="toc-Specifications_for_respirators" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Specifications_for_respirators"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.1</span> <span>Specifications for respirators</span> </div> </a> <ul id="toc-Specifications_for_respirators-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Marketing" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Marketing"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.2</span> <span>Marketing</span> </div> </a> <ul id="toc-Marketing-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li 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<a class="vector-toc-link" href="#Biomedical"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1</span> <span>Biomedical</span> </div> </a> <ul id="toc-Biomedical-sublist" class="vector-toc-list"> <li id="toc-COVID-19" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#COVID-19"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1.1</span> <span>COVID-19</span> </div> </a> <ul id="toc-COVID-19-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Vacuum_cleaners" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Vacuum_cleaners"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2</span> <span>Vacuum cleaners</span> </div> </a> <ul id="toc-Vacuum_cleaners-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Heating,_ventilation,_and_air_conditioning" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Heating,_ventilation,_and_air_conditioning"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.3</span> <span>Heating, ventilation, and air conditioning</span> </div> </a> <ul id="toc-Heating,_ventilation,_and_air_conditioning-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Vehicles" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Vehicles"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.4</span> <span>Vehicles</span> </div> </a> <ul id="toc-Vehicles-sublist" class="vector-toc-list"> <li id="toc-Airlines" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Airlines"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.4.1</span> <span>Airlines</span> </div> </a> <ul id="toc-Airlines-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Motor_vehicles" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Motor_vehicles"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.4.2</span> <span>Motor vehicles</span> </div> </a> <ul id="toc-Motor_vehicles-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> </ul> </li> <li id="toc-History" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#History"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>History</span> </div> </a> <ul id="toc-History-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Further_reading" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Further_reading"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>Further reading</span> </div> </a> <ul id="toc-Further_reading-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" title="Table of Contents" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" 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Available in 27 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-27" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">27 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D9%87%D9%88%D8%A7%D8%A1_%D8%B9%D8%A7%D9%84%D9%8A_%D9%83%D9%81%D8%A7%D8%A1%D8%A9_%D8%A7%D9%84%D8%AC%D8%B3%D9%8A%D9%85%D8%A7%D8%AA" title="هواء عالي كفاءة الجسيمات – Arabic" lang="ar" hreflang="ar" data-title="هواء عالي كفاءة الجسيمات" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/HEPA-%D1%84%D0%B8%D0%BB%D1%82%D1%8A%D1%80" title="HEPA-филтър – Bulgarian" lang="bg" hreflang="bg" data-title="HEPA-филтър" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Filtre_HEPA" title="Filtre HEPA – Catalan" lang="ca" hreflang="ca" data-title="Filtre HEPA" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/HEPA_filtr" title="HEPA filtr – Czech" lang="cs" hreflang="cs" data-title="HEPA filtr" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Schwebstofffilter" title="Schwebstofffilter – German" lang="de" hreflang="de" data-title="Schwebstofffilter" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/HEPA" title="HEPA – Spanish" lang="es" hreflang="es" data-title="HEPA" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D9%81%DB%8C%D9%84%D8%AA%D8%B1_%D9%87%D9%BE%D8%A7" title="فیلتر هپا – Persian" lang="fa" hreflang="fa" data-title="فیلتر هپا" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Filtre_HEPA" title="Filtre HEPA – French" lang="fr" hreflang="fr" data-title="Filtre HEPA" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/HEPA" title="HEPA – Korean" lang="ko" hreflang="ko" data-title="HEPA" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%85%E0%A4%A6%E0%A4%95_%E0%A4%9B%E0%A4%A8%E0%A5%8D%E0%A4%A8%E0%A5%80" title="अदक छन्नी – Hindi" lang="hi" hreflang="hi" data-title="अदक छन्नी" data-language-autonym="हिन्दी" data-language-local-name="Hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/HEPA" title="HEPA – Indonesian" lang="id" hreflang="id" data-title="HEPA" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Filtro_HEPA" title="Filtro HEPA – Italian" lang="it" hreflang="it" data-title="Filtro HEPA" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/HEPA" title="HEPA – Hebrew" lang="he" hreflang="he" data-title="HEPA" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-mn mw-list-item"><a href="https://mn.wikipedia.org/wiki/HEPA_%D1%88%D2%AF%D2%AF%D0%BB%D1%82%D2%AF%D2%AF%D1%80%D0%B8%D0%B9%D0%BD_%D1%81%D1%82%D0%B0%D0%BD%D0%B4%D0%B0%D1%80%D1%82" title="HEPA шүүлтүүрийн стандарт – Mongolian" lang="mn" hreflang="mn" data-title="HEPA шүүлтүүрийн стандарт" data-language-autonym="Монгол" data-language-local-name="Mongolian" class="interlanguage-link-target"><span>Монгол</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/HEPA" title="HEPA – Dutch" lang="nl" hreflang="nl" data-title="HEPA" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/HEPA" title="HEPA – Japanese" lang="ja" hreflang="ja" data-title="HEPA" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/HEPA-filter" title="HEPA-filter – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="HEPA-filter" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/HEPA" title="HEPA – Polish" lang="pl" hreflang="pl" data-title="HEPA" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Filtro_HEPA" title="Filtro HEPA – Portuguese" lang="pt" hreflang="pt" data-title="Filtro HEPA" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/HEPA" title="HEPA – Russian" lang="ru" hreflang="ru" data-title="HEPA" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Filter_HEPA" title="Filter HEPA – Slovak" lang="sk" hreflang="sk" data-title="Filter HEPA" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/HEPA-suodatin" title="HEPA-suodatin – Finnish" lang="fi" hreflang="fi" data-title="HEPA-suodatin" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/HEPA-filter" title="HEPA-filter – Swedish" lang="sv" hreflang="sv" data-title="HEPA-filter" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/HEPA" title="HEPA – Turkish" lang="tr" hreflang="tr" data-title="HEPA" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%A4%D1%96%D0%BB%D1%8C%D1%82%D1%80_HEPA" title="Фільтр HEPA – Ukrainian" lang="uk" hreflang="uk" data-title="Фільтр HEPA" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/B%E1%BB%99_l%E1%BB%8Dc_HEPA" title="Bộ lọc HEPA – Vietnamese" lang="vi" hreflang="vi" data-title="Bộ lọc HEPA" data-language-autonym="Tiếng Việt" data-language-local-name="Vietnamese" class="interlanguage-link-target"><span>Tiếng Việt</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E9%AB%98%E6%95%88%E6%BB%A4%E7%BD%91" title="高效滤网 – Chinese" lang="zh" hreflang="zh" data-title="高效滤网" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q948441#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit 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.mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">For other uses, see <a href="/wiki/HEPA_(disambiguation)" class="mw-disambig" title="HEPA (disambiguation)">HEPA (disambiguation)</a>.</div> <p class="mw-empty-elt"> </p> <style data-mw-deduplicate="TemplateStyles:r1257001546">.mw-parser-output .infobox-subbox{padding:0;border:none;margin:-3px;width:auto;min-width:100%;font-size:100%;clear:none;float:none;background-color:transparent}.mw-parser-output .infobox-3cols-child{margin:auto}.mw-parser-output .infobox .navbar{font-size:100%}@media screen{html.skin-theme-clientpref-night .mw-parser-output .infobox-full-data:not(.notheme)>div:not(.notheme)[style]{background:#1f1f23!important;color:#f8f9fa}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox-full-data:not(.notheme) div:not(.notheme){background:#1f1f23!important;color:#f8f9fa}}@media(min-width:640px){body.skin--responsive .mw-parser-output .infobox-table{display:table!important}body.skin--responsive .mw-parser-output .infobox-table>caption{display:table-caption!important}body.skin--responsive .mw-parser-output .infobox-table>tbody{display:table-row-group}body.skin--responsive .mw-parser-output .infobox-table tr{display:table-row!important}body.skin--responsive .mw-parser-output .infobox-table th,body.skin--responsive .mw-parser-output .infobox-table td{padding-left:inherit;padding-right:inherit}}</style><table class="infobox"><tbody><tr><th colspan="2" class="infobox-above" style="background-color: lightblue">HEPA</th></tr><tr><td colspan="2" class="infobox-image"><span class="mw-default-size" typeof="mw:File/Frameless"><a href="/wiki/File:HEPA_Filter_diagram_en.svg" class="mw-file-description"><img alt="Schematic of HEPA filter" src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b1/HEPA_Filter_diagram_en.svg/290px-HEPA_Filter_diagram_en.svg.png" decoding="async" width="290" height="260" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b1/HEPA_Filter_diagram_en.svg/435px-HEPA_Filter_diagram_en.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b1/HEPA_Filter_diagram_en.svg/580px-HEPA_Filter_diagram_en.svg.png 2x" data-file-width="607" data-file-height="544" /></a></span><div class="infobox-caption">HEPA filter corrugated internal structure and aluminium support along with the description of its functioning principle (interception, impact and diffusion of dust particles through a dense non-woven fiber material)</div></td></tr><tr><th colspan="2" class="infobox-header" style="background: #ddf;">Overview</th></tr><tr><th scope="row" class="infobox-label" style="background: #ddf;">Other names</th><td class="infobox-data">High-Efficiency Particulate Air, High-Efficiency Particulate Arresting filter, HEPA</td></tr><tr><th scope="row" class="infobox-label" style="background: #ddf;">Standards</th><td class="infobox-data">DOE NE F 3-45, EN 1822, ISO 29463</td></tr><tr><td colspan="2" class="infobox-full-data"><div style="text-align: right;">[<a href="https://www.wikidata.org/wiki/Q948441" class="extiw" title="d:Q948441">edit on Wikidata</a>]</div></td></tr></tbody></table> <p><b>HEPA</b> (<span class="rt-commentedText nowrap"><span class="IPA nopopups noexcerpt" lang="en-fonipa"><a href="/wiki/Help:IPA/English" title="Help:IPA/English">/<span style="border-bottom:1px dotted"><span title="/ˈ/: primary stress follows">ˈ</span><span title="'h' in 'hi'">h</span><span title="/ɛ/: 'e' in 'dress'">ɛ</span><span title="'p' in 'pie'">p</span><span title="/ə/: 'a' in 'about'">ə</span></span>/</a></span></span>, <b>high efficiency particulate air</b>) filter,<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> also known as a <b>high efficiency particulate arresting</b> filter,<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> is an <a href="/wiki/Efficiency" title="Efficiency">efficiency</a> standard of <a href="/wiki/Air_filter" title="Air filter">air filters</a>.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p><p>Filters meeting the HEPA standard must satisfy certain levels of efficiency. Common standards require that a HEPA air filter must remove—from the air that passes through—at least 99.95% (<a href="/wiki/International_Organization_for_Standardization" title="International Organization for Standardization">ISO</a>, European Standard)<sup id="cite_ref-ISO_29463_4-0" class="reference"><a href="#cite_note-ISO_29463-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> or 99.97% (<a href="/wiki/American_Society_of_Mechanical_Engineers" title="American Society of Mechanical Engineers">ASME</a>, <a href="/wiki/United_States_Department_of_Energy" title="United States Department of Energy">U.S. DOE</a>)<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-:1_7-0" class="reference"><a href="#cite_note-:1-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> of <a href="/wiki/Particle" title="Particle">particles</a> whose diameter is equal to 0.3 <a href="/wiki/Micrometre" title="Micrometre">μm</a>, with the filtration efficiency increasing for particle diameters both less than and greater than 0.3 μm.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> HEPA filters capture <a href="/wiki/Pollen" title="Pollen">pollen</a>, <a href="/wiki/Dirt" title="Dirt">dirt</a>, <a href="/wiki/Dust" title="Dust">dust</a>, <a href="/wiki/Moisture" title="Moisture">moisture</a>, <a href="/wiki/Bacteria" title="Bacteria">bacteria</a> (0.2–2.0 μm), <a href="/wiki/Viruses" class="mw-redirect" title="Viruses">viruses</a> (0.02–0.3 μm), and submicron liquid <a href="/wiki/Aerosol" title="Aerosol">aerosol</a> (0.02–0.5 μm).<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> Some <a href="/wiki/Microorganism" title="Microorganism">microorganisms</a>, for example, <i><a href="/wiki/Aspergillus_niger" title="Aspergillus niger">Aspergillus niger</a></i>, <i><a href="/wiki/Penicillium_citrinum" title="Penicillium citrinum">Penicillium citrinum</a></i>, <i><a href="/wiki/Staphylococcus_epidermidis" title="Staphylococcus epidermidis">Staphylococcus epidermidis</a></i>, and <i><a href="/wiki/Bacillus_subtilis" title="Bacillus subtilis">Bacillus subtilis</a></i> are captured by HEPA filters with <a href="/wiki/Photocatalysis" title="Photocatalysis">photocatalytic</a> oxidation (PCO). A HEPA filter is also able to capture some viruses and bacteria which are ≤0.3 μm.<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> A HEPA filter is also able to capture floor dust which contains <a href="/wiki/Bacteroidia" class="mw-redirect" title="Bacteroidia">bacteroidia</a>, <a href="/wiki/Clostridia" title="Clostridia">clostridia</a>, and <a href="/wiki/Bacilli" title="Bacilli">bacilli</a>.<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> HEPA was commercialized in the 1950s, and the original term became a registered <a href="/wiki/Trademark" title="Trademark">trademark</a> and later a <a href="/wiki/Generic_trademark" title="Generic trademark">generic trademark</a> for highly efficient filters.<sup id="cite_ref-:0_14-0" class="reference"><a href="#cite_note-:0-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> HEPA filters are used in applications that require <a href="/wiki/Contamination_control" title="Contamination control">contamination control</a>, such as the manufacturing of hard disk drives, medical devices, semiconductors, nuclear, food and pharmaceutical products, as well as in hospitals,<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> homes, and vehicles. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Mechanism">Mechanism</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=HEPA&action=edit&section=1" title="Edit section: Mechanism"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Filter_collection_mechanisms.svg" class="mw-file-description"><img alt="Four diagram each showing the path of small particle as it approaches a large fiber according to each of the four mechanisms" src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c7/Filter_collection_mechanisms.svg/220px-Filter_collection_mechanisms.svg.png" decoding="async" width="220" height="257" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c7/Filter_collection_mechanisms.svg/330px-Filter_collection_mechanisms.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c7/Filter_collection_mechanisms.svg/440px-Filter_collection_mechanisms.svg.png 2x" data-file-width="795" data-file-height="930" /></a><figcaption>The four primary filter collection mechanisms: <a href="/wiki/Diffusion" title="Diffusion">diffusion</a>, interception, inertial impaction, and <a href="/wiki/Electrostatics" title="Electrostatics">electrostatic</a> attraction (air flow direction from left to right)</figcaption></figure> <figure typeof="mw:File/Thumb"><a href="/wiki/File:Filteration_Collection_Mechanisms-en.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/9/97/Filteration_Collection_Mechanisms-en.svg/400px-Filteration_Collection_Mechanisms-en.svg.png" decoding="async" width="400" height="238" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/97/Filteration_Collection_Mechanisms-en.svg/600px-Filteration_Collection_Mechanisms-en.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/97/Filteration_Collection_Mechanisms-en.svg/800px-Filteration_Collection_Mechanisms-en.svg.png 2x" data-file-width="709" data-file-height="422" /></a><figcaption>Classic Collection Efficiency Curve with Filter Collection Mechanisms</figcaption></figure> <p>HEPA filters are composed of a <a href="/wiki/Depth_filter" title="Depth filter">mat of randomly arranged fibers</a>.<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> The fibers are typically composed of <a href="/wiki/Polypropylene" title="Polypropylene">polypropylene</a> or <a href="/wiki/Fiberglass" title="Fiberglass">fiberglass</a> with diameters between 0.5 and 2.0 micrometers. Most of the time, these filters are composed of tangled bundles of fine <a href="/wiki/Fiber" title="Fiber">fibers</a>. These fibers create a narrow convoluted pathway through which air passes. When the largest particles are passing through this pathway, the bundles of fibers behave like a kitchen sieve which physically blocks the particles from passing through. However, when smaller particles pass with the air, as the air twists and turns, the smaller particles cannot keep up with the motion of the air and thus they collide with the fibers. The smallest particles have very little inertia and move randomly as a result of collisions with individual air molecules (<a href="/wiki/Brownian_motion" title="Brownian motion">Brownian motion</a>). Because of their movement, they end up crashing into the fibers.<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> Key factors affecting its functions are fiber diameter, filter thickness, and face velocity, which is the measured air speed at an inlet or outlet of a heating ventilation and air conditioning (HVAC) system. Face velocity is measured in m/s and can be calculated as the volume flow rate (m<sup>3</sup>/s) divided by the face area (m<sup>2</sup>). The air space between HEPA filter fibers is typically much greater than 0.3 μm. HEPA filters in very high level for smallest particulate matter. Unlike <a href="/wiki/Sieve" title="Sieve">sieves</a> or <a href="/wiki/Membrane_technology" title="Membrane technology">membrane filters</a>, where particles smaller than openings or pores can pass through, HEPA filters are designed to target a range of particle sizes. These particles are trapped (they stick to a fiber) through a combination of the following three mechanisms: </p> <ol><li>Diffusion; particles below 0.3 μm are captured by <a href="/wiki/Diffusion" title="Diffusion">diffusion</a> in a HEPA filter. This mechanism is a result of the collision with <a href="/wiki/Gas" title="Gas">gas</a> <a href="/wiki/Molecule" title="Molecule">molecules</a> by the smallest particles, especially those below 0.1 μm in diameter. The small particles are effectively blown or bounced around and collide with the filter media fibers. This behavior is similar to <a href="/wiki/Brownian_motion" title="Brownian motion">Brownian motion</a> and raises the probability that a particle will be stopped by either interception or impaction; this mechanism becomes dominant at lower <a href="/wiki/Airflow" title="Airflow">airflow</a>.</li> <li>Interception; particles following a line of flow in the air stream come within one <a href="/wiki/Radius" title="Radius">radius</a> of a fiber and adhere to it. Mid size particles are being captured by this process.</li> <li>Impaction; larger particles are unable to avoid fibers by following the curving contours of the air stream and are forced to embed in one of them directly; this effect increases with diminishing fiber separation and higher air flow velocity.</li></ol> <p>Diffusion predominates below the 0.1 μm diameter particle size, whilst impaction and interception predominate above 0.4 μm.<sup id="cite_ref-Woodford_18-0" class="reference"><a href="#cite_note-Woodford-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> In between, near the most penetrating particle size (MPPS) 0.21 μm, both diffusion and interception are comparatively inefficient.<sup id="cite_ref-Roza_19-0" class="reference"><a href="#cite_note-Roza-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> Because this is the weakest point in the filter's performance, the HEPA specifications use the retention of particles near this size (0.3 μm) to classify the filter.<sup id="cite_ref-Woodford_18-1" class="reference"><a href="#cite_note-Woodford-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> However it is possible for particles smaller than the MPPS to not have filtering efficiency greater than that of the MPPS. This is due to the fact that these particles can act as <a href="/wiki/Nucleation" title="Nucleation">nucleation</a> sites for mostly <a href="/wiki/Condensation" title="Condensation">condensation</a> and form particles near the MPPS.<sup id="cite_ref-Roza_19-1" class="reference"><a href="#cite_note-Roza-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Gas_filtration">Gas filtration</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=HEPA&action=edit&section=2" title="Edit section: Gas filtration"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>HEPA filters are designed to arrest very fine particles effectively, but they do not filter out gasses and <a href="/wiki/Odor" title="Odor">odor</a> molecules. Circumstances requiring filtration of <a href="/wiki/Volatile_organic_compound" title="Volatile organic compound">volatile organic compounds</a>, chemical vapors, or <a href="/wiki/Cigarette" title="Cigarette">cigarette</a>, pet or <a href="/wiki/Flatulence" title="Flatulence">flatulence</a> odors call for the use of an <a href="/wiki/Activated_carbon" title="Activated carbon">activated carbon</a> (charcoal) or other type of filter instead of or in addition to a HEPA filter.<sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> Carbon cloth filters, claimed to be many times more efficient than the granular activated carbon form at <a href="/wiki/Adsorption" title="Adsorption">adsorption</a> of gaseous <a href="/wiki/Pollutant" title="Pollutant">pollutants</a>, are known as high efficiency gas adsorption filters (HEGA) and were originally developed by the British Armed Forces as a defense against <a href="/wiki/Chemical_warfare" title="Chemical warfare">chemical warfare</a>.<sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Pre-filter_and_HEPA_filter">Pre-filter and HEPA filter</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=HEPA&action=edit&section=3" title="Edit section: Pre-filter and HEPA filter"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A HEPA bag filter can be used in conjunction with a pre-filter (usually carbon-activated) to extend the usage life of the more expensive HEPA filter.<sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> In such setup, the first stage in the <a href="/wiki/Filtration" title="Filtration">filtration</a> process is made up of a pre-filter which removes most of the larger dust, <a href="/wiki/Hair" title="Hair">hair</a>, PM10 and pollen particles from the air. The second stage high-quality HEPA filter removes the finer particles that escape from the pre-filter. This is common in <a href="/wiki/Air_handler" title="Air handler">air handling units</a>.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2024)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading2"><h2 id="Specifications">Specifications</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=HEPA&action=edit&section=4" title="Edit section: Specifications"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:HEPA_filter_unit.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/06/HEPA_filter_unit.jpg/220px-HEPA_filter_unit.jpg" decoding="async" width="220" height="147" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/06/HEPA_filter_unit.jpg/330px-HEPA_filter_unit.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/06/HEPA_filter_unit.jpg/440px-HEPA_filter_unit.jpg 2x" data-file-width="3888" data-file-height="2592" /></a><figcaption>A portable HEPA filtration unit used to clean air after a fire, or during manufacturing processes</figcaption></figure> <p>HEPA filters, as defined by the United States Department of Energy (DOE) standard adopted by most American industries, remove at least 99.97% of aerosols 0.3 micrometers (μm) in diameter.<sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> The filter's minimal resistance to airflow, or <a href="/wiki/Pressure_drop" title="Pressure drop">pressure drop</a>, is usually specified around 300 pascals (0.044 psi) at its nominal <a href="/wiki/Volumetric_flow_rate" title="Volumetric flow rate">volumetric flow rate</a>.<sup id="cite_ref-:1_7-1" class="reference"><a href="#cite_note-:1-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p><p>The specification used in the <a href="/wiki/European_Union" title="European Union">European Union</a>: European Standard EN 1822-1:2019, from which ISO 29463 is derived,<sup id="cite_ref-ISO_29463_4-1" class="reference"><a href="#cite_note-ISO_29463-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> defines several classes of filters by their retention at the given most penetrating particle size (MPPS): <i>Efficient Particulate Air filters</i> (EPA), <i>High Efficiency Particulate Air filters</i> (HEPA), and <i><a href="/wiki/Ultra-low_particulate_air" title="Ultra-low particulate air">Ultra Low Particulate Air filters</a></i> (ULPA). The averaged efficiency of the filter is called "overall", and the efficiency at a specific point is called "local":<sup id="cite_ref-ISO_29463_4-2" class="reference"><a href="#cite_note-ISO_29463-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p> <table class="wikitable"> <tbody><tr> <th>Efficiency</th> <th>EN 1822</th> <th>ISO 29463</th> <th>Retention (averaged)</th> <th>Retention (spot) </th></tr> <tr> <td rowspan="3" align="center">EPA </td> <td align="center">E10</td> <td align="center">—</td> <td>≥ 85%</td> <td align="center">— </td></tr> <tr> <td align="center">E11</td> <td align="center">ISO 15 E<br />ISO 20 E</td> <td>≥ 95%<br />≥ 99%</td> <td align="center">— </td></tr> <tr> <td align="center">E12</td> <td align="center">ISO 25 E<br />ISO 30 E</td> <td>≥ 99.5%<br />≥ 99.9%</td> <td align="center">— </td></tr> <tr> <td rowspan="2" align="center"><b>HEPA</b> </td> <td align="center">H13</td> <td align="center">ISO 35 H<br />ISO 40 H</td> <td>≥ 99.95%<br />≥ 99.99%</td> <td>≥ 99.75%<br />≥ 99.95% </td></tr> <tr> <td align="center">H14</td> <td align="center">ISO 45 H<br />ISO 50 U</td> <td>≥ 99.995%<br />≥ 99.999%</td> <td>≥ 99.975%<br />≥ 99.995% </td></tr> <tr> <td rowspan="3" align="center">ULPA </td> <td align="center">U15</td> <td align="center">ISO 55 U<br />ISO 60 U</td> <td>≥ 99.9995%<br />≥ 99.9999%</td> <td>≥ 99.9975%<br />≥ 99.9995% </td></tr> <tr> <td align="center">U16</td> <td align="center">ISO 65 U<br />ISO 70 U</td> <td>≥ 99.99995%<br />≥ 99.99999%</td> <td>≥ 99.99975%<br />≥ 99.9999% </td></tr> <tr> <td align="center">U17</td> <td align="center">ISO 75 U</td> <td>≥ 99.999995%</td> <td>≥ 99.9999% </td></tr></tbody></table> <p>See also the different classes for <a href="/wiki/Air_filter#Filter_classes" title="Air filter">air filters</a> for comparison. </p> <div class="mw-heading mw-heading3"><h3 id="Specifications_for_respirators">Specifications for respirators</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=HEPA&action=edit&section=5" title="Edit section: Specifications for respirators"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1257001546" /><table class="infobox"><tbody><tr><th colspan="2" class="infobox-above" style="background: #A31BAA;"><span style="color:#FFFFFF;">HEPA</span></th></tr><tr><th scope="row" class="infobox-label" style="background: #ddf;">Other name(s)</th><td class="infobox-data">High-Efficiency Particulate Air, High-Efficiency Particulate Arresting filter, HEPA</td></tr><tr><th scope="row" class="infobox-label" style="background: #ddf;">Regulated by</th><td class="infobox-data"><a href="/wiki/United_States_Department_of_Energy" title="United States Department of Energy">United States Department of Energy</a>, <a href="/wiki/Mine_Safety_and_Health_Administration" title="Mine Safety and Health Administration">Mine Safety and Health Administration</a>, <a href="/wiki/National_Institute_for_Occupational_Safety_and_Health" title="National Institute for Occupational Safety and Health">National Institute for Occupational Safety and Health</a></td></tr><tr><th scope="row" class="infobox-label" style="background: #ddf;">Regulation</th><td class="infobox-data"><a href="/wiki/30_CFR_11" class="mw-redirect" title="30 CFR 11">30 CFR 11</a>, <a href="/wiki/42_CFR_84" class="mw-redirect" title="42 CFR 84">42 CFR 84</a>, <a href="/wiki/DOE_NE_F_3-45" class="mw-redirect" title="DOE NE F 3-45">DOE NE F 3-45</a></td></tr><tr><th scope="row" class="infobox-label" style="background: #ddf;"><a href="/wiki/NIOSH_air_filtration_rating#Table_of_TC/BM_Approval_Schedules" title="NIOSH air filtration rating">NIOSH</a> schedule</th><td class="infobox-data">TC-21C</td></tr><tr><td colspan="2" class="infobox-full-data"><div style="text-align: right;">[<a href="https://www.wikidata.org/wiki/Q948441" class="extiw" title="d:Q948441">edit on Wikidata</a>]</div></td></tr></tbody></table> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951" /><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/NIOSH_air_filtration_rating" title="NIOSH air filtration rating">NIOSH air filtration rating</a></div> <p>For <a href="/wiki/Respirator" title="Respirator">respirators</a>, <a href="/wiki/Mine_Safety_and_Health_Administration" title="Mine Safety and Health Administration">MSHA</a> and <a href="/wiki/NIOSH" class="mw-redirect" title="NIOSH">NIOSH</a> define HEPA as filters blocking ≥ 99.97% of 0.3 micron <a href="/wiki/Dioctyl_phthalate" class="mw-redirect" title="Dioctyl phthalate">DOP</a> particles, under 30 CFR 11 and 42 CFR 84. Since the transition to 42 CFR 84 in 1995, use of the term HEPA has been deprecated except for <a href="/wiki/Powered_air-purifying_respirator" title="Powered air-purifying respirator">powered air-purifying respirators</a>.<sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> However, by definition, ANSI Z88.2-2015 considers N100, R100, P100, and HE as HEPA filters.<sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Marketing">Marketing</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=HEPA&action=edit&section=6" title="Edit section: Marketing"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Some companies use the marketing term "True HEPA" to give consumers assurance that their air filters meet the HEPA standard, although this term has no legal or scientific meaning.<sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> Products that are marketed to be "HEPA-type," "HEPA-like," "HEPA-style" or "99% HEPA" do not satisfy the HEPA standard and may not have been tested in independent laboratories. Although such filters may come reasonably close to HEPA standards, others fall significantly short.<sup id="cite_ref-28" class="reference"><a href="#cite_note-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Efficacy_and_safety">Efficacy and safety</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=HEPA&action=edit&section=7" title="Edit section: Efficacy and safety"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In general terms (and allowing for some variation depending on factors such as the air-flow rate, the physical properties of the particles being filtered, as well as engineering details of the entire filtration-system design and not just the filter-media properties), HEPA filters experience the most difficulty in capturing particles in the size range of 0.15 to 0.2 μm.<sup id="cite_ref-29" class="reference"><a href="#cite_note-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> HEPA filtration works by mechanical means, unlike ionic and <a href="/wiki/Ozone" title="Ozone">ozone</a> treatment technologies, which use negative <a href="/wiki/Ion" title="Ion">ions</a> and ozone gas respectively. So, the likelihood of potential triggering of pulmonary side-effects such as <a href="/wiki/Asthma" title="Asthma">asthma</a><sup id="cite_ref-30" class="reference"><a href="#cite_note-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> and <a href="/wiki/Allergy" title="Allergy">allergies</a> is much lower with HEPA purifiers.<sup id="cite_ref-31" class="reference"><a href="#cite_note-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> </p><p>To ensure that a HEPA filter is working efficiently, the filters should be inspected and changed at least every six months in commercial settings. In residential settings, and depending on the general ambient air quality, these filters can be changed every two to three years. Failing to change a HEPA filter in a timely fashion will result in it putting stress on the machine or system and not removing particles from the air properly. Additionally, depending on the gasketing materials chosen in the design of the system, a clogged HEPA filter can result in extensive bypassing of airflow around the filter.<sup id="cite_ref-32" class="reference"><a href="#cite_note-32"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Applications">Applications</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=HEPA&action=edit&section=8" title="Edit section: Applications"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1251242444">.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}</style><table class="box-More_citations_needed_section plainlinks metadata ambox ambox-content ambox-Refimprove" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><a href="/wiki/File:Question_book-new.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/50px-Question_book-new.svg.png" decoding="async" width="50" height="39" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/75px-Question_book-new.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/99/Question_book-new.svg/100px-Question_book-new.svg.png 2x" data-file-width="512" data-file-height="399" /></a></span></div></td><td class="mbox-text"><div class="mbox-text-span">This section <b>needs additional citations for <a href="/wiki/Wikipedia:Verifiability" title="Wikipedia:Verifiability">verification</a></b>.<span class="hide-when-compact"> Please help <a href="/wiki/Special:EditPage/HEPA" title="Special:EditPage/HEPA">improve this article</a> by <a href="/wiki/Help:Referencing_for_beginners" title="Help:Referencing for beginners">adding citations to reliable sources</a> in this section. Unsourced material may be challenged and removed.</span> <span class="date-container"><i>(<span class="date">June 2024</span>)</i></span><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> <figure class="mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Portable_powered_HEPA_respirator.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b9/Portable_powered_HEPA_respirator.jpg/180px-Portable_powered_HEPA_respirator.jpg" decoding="async" width="180" height="240" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b9/Portable_powered_HEPA_respirator.jpg/270px-Portable_powered_HEPA_respirator.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b9/Portable_powered_HEPA_respirator.jpg/360px-Portable_powered_HEPA_respirator.jpg 2x" data-file-width="2136" data-file-height="2848" /></a><figcaption>Hospital staff modelling a <a href="/wiki/Powered,_air-purifying_respirator" class="mw-redirect" title="Powered, air-purifying respirator">powered, air-purifying respirator</a> (PAPR) fitted with a HEPA filter, used to protect from airborne or aerosolised pathogens such as <a href="/wiki/Tuberculosis" title="Tuberculosis">tuberculosis</a></figcaption></figure> <div class="mw-heading mw-heading3"><h3 id="Biomedical">Biomedical</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=HEPA&action=edit&section=9" title="Edit section: Biomedical"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>HEPA filters are critical in the prevention of the spread of airborne bacterial and viral organisms and, therefore, <a href="/wiki/Infection" title="Infection">infection</a>. Typically, medical use HEPA filtration systems also incorporate high-energy <a href="/wiki/Ultraviolet" title="Ultraviolet">ultraviolet</a> light units or panels with anti-microbial coating to kill off the live bacteria and viruses trapped by the filter media.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (June 2019)">citation needed</span></a></i>]</sup> </p><p>Some of the best-rated HEPA units have an efficiency rating of 99.995%, which assures a very high level of protection against <a href="/wiki/Airborne_transmission" title="Airborne transmission">airborne disease transmission</a>.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2024)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading4"><h4 id="COVID-19">COVID-19</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=HEPA&action=edit&section=10" title="Edit section: COVID-19"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>HEPA filters are capable of removing viruses including COVID-19 (particles of 60-140 nanometer diameter) from the air, and as such saw a surge in adoption during the pandemic in order to mitigate infection risks. To combat supply chain and cost issues hindering adoption of HEPA filters during the COVID-19 pandemic, a professor at <a href="/wiki/University_of_California,_Davis" title="University of California, Davis">University of California, Davis</a>, created a simple <a href="/wiki/Do_it_yourself" title="Do it yourself">do-it-yourself</a> <a href="/wiki/Air_purifier" title="Air purifier">air purifier</a> design called crbox(<a href="/wiki/Corsi%E2%80%93Rosenthal_Box" title="Corsi–Rosenthal Box">Corsi–Rosenthal Box</a>). It involves arranging 4 HEPA filters in a cubic shape, the bottom being made out of cardboard, sealing the filter sides with tape and adding a fan on top. In addition, the COVID-19 Pandemic resulted in a surge of new air purifier products from new and established brands such as <a href="/wiki/Dyson_(company)" title="Dyson (company)">Dyson</a> or <a href="/wiki/Xiaomi" title="Xiaomi">Xiaomi</a> hitting the markets. </p> <div class="mw-heading mw-heading3"><h3 id="Vacuum_cleaners">Vacuum cleaners</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=HEPA&action=edit&section=11" title="Edit section: Vacuum cleaners"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:PHILIPS_HEPA_H10_air_filter_for_vacuum_cleaner.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e5/PHILIPS_HEPA_H10_air_filter_for_vacuum_cleaner.JPG/220px-PHILIPS_HEPA_H10_air_filter_for_vacuum_cleaner.JPG" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e5/PHILIPS_HEPA_H10_air_filter_for_vacuum_cleaner.JPG/330px-PHILIPS_HEPA_H10_air_filter_for_vacuum_cleaner.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e5/PHILIPS_HEPA_H10_air_filter_for_vacuum_cleaner.JPG/440px-PHILIPS_HEPA_H10_air_filter_for_vacuum_cleaner.JPG 2x" data-file-width="7300" data-file-height="5470" /></a><figcaption>HEPA original filter for Philips FC87xx-series vacuum cleaners</figcaption></figure> <p>Many <a href="/wiki/Vacuum_cleaner" title="Vacuum cleaner">vacuum cleaners</a> also use HEPA filters as part of their filtration systems. This is beneficial for asthma and allergy sufferers, because the HEPA filter traps the fine particles (such as pollen and <a href="/wiki/House_dust_mite" title="House dust mite">house dust mite</a> <a href="/wiki/Feces" title="Feces">feces</a>) which trigger allergy and asthma symptoms. For a HEPA filter in a vacuum cleaner to be effective, the vacuum cleaner must be designed so that <i>all</i> the air drawn into the machine is expelled through the filter, with none of the air leaking past it. This is often referred to as "Sealed HEPA" or sometimes the more vague "True HEPA". Vacuum cleaners simply labeled "HEPA" may have a HEPA filter, but not all air necessarily passes through it. Finally, vacuum cleaner filters marketed as "HEPA-like" will typically use a filter of a <i>similar construction</i> to HEPA, but without the filtering efficiency. Because of the extra density of a true HEPA filter, HEPA vacuum cleaners require more powerful motors to provide adequate cleaning power.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2024)">citation needed</span></a></i>]</sup> </p><p>Some newer models claim to be better than the earlier ones with the inclusion of "washable" filters. Generally, washable true HEPA filters are expensive. A high-quality HEPA filter can trap 99.97% of dust particles that are 0.3 microns in diameter. For comparison, a human hair is about 50 to 150 microns in diameter. So, a true HEPA filter is effectively trapping particles several hundred times smaller than the width of a human hair.<sup id="cite_ref-33" class="reference"><a href="#cite_note-33"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> Some manufacturers claim filter standards such as "HEPA 4," without explaining the meaning behind them.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (February 2023)">citation needed</span></a></i>]</sup> This refers to their <a href="/wiki/Minimum_efficiency_reporting_value" title="Minimum efficiency reporting value">Minimum Efficiency Reporting Value</a> (MERV) rating.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (February 2023)">citation needed</span></a></i>]</sup> These ratings are used to rate the ability of an air cleaner filter to remove dust from the air as it passes through the filter. MERV is a standard used to measure the overall efficiency of a filter. The MERV scale ranges from 1 to 16, and measures a filter's ability to remove particles from 10 to 0.3 micrometer in size. Filters with higher ratings not only remove more particles from the air, but they also remove smaller particles. </p> <div class="mw-heading mw-heading3"><h3 id="Heating,_ventilation,_and_air_conditioning"><span id="Heating.2C_ventilation.2C_and_air_conditioning"></span>Heating, ventilation, and air conditioning</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=HEPA&action=edit&section=12" title="Edit section: Heating, ventilation, and air conditioning"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><span><video id="mwe_player_0" poster="//upload.wikimedia.org/wikipedia/commons/thumb/f/f1/Display_VSON_WP6910_%28air_detector%29_-_pm2%2C5_at_Verona_%28Borgo_Milano%29_Italy_-_%28particulate_pollution%2C_polveri_sottili%29_-_2020_01_30_%28hour_22-37%29_-_OUTdoor_and_INdoor_%28HEPA_H13_filter%29_-_first_publication_commons.wikimedia.org.webm/220px--thumbnail.webm.jpg" controls="" preload="none" data-mw-tmh="" class="mw-file-element" width="220" height="180" data-durationhint="500" data-mwtitle="Display_VSON_WP6910_(air_detector)_-_pm2,5_at_Verona_(Borgo_Milano)_Italy_-_(particulate_pollution,_polveri_sottili)_-_2020_01_30_(hour_22-37)_-_OUTdoor_and_INdoor_(HEPA_H13_filter)_-_first_publication_commons.wikimedia.org.webm" data-mwprovider="wikimediacommons" resource="/wiki/File:Display_VSON_WP6910_(air_detector)_-_pm2,5_at_Verona_(Borgo_Milano)_Italy_-_(particulate_pollution,_polveri_sottili)_-_2020_01_30_(hour_22-37)_-_OUTdoor_and_INdoor_(HEPA_H13_filter)_-_first_publication_commons.wikimedia.org.webm"><source src="//upload.wikimedia.org/wikipedia/commons/f/f1/Display_VSON_WP6910_%28air_detector%29_-_pm2%2C5_at_Verona_%28Borgo_Milano%29_Italy_-_%28particulate_pollution%2C_polveri_sottili%29_-_2020_01_30_%28hour_22-37%29_-_OUTdoor_and_INdoor_%28HEPA_H13_filter%29_-_first_publication_commons.wikimedia.org.webm" type="video/webm; codecs="vp8, vorbis"" data-width="624" data-height="511" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/f/f1/Display_VSON_WP6910_%28air_detector%29_-_pm2%2C5_at_Verona_%28Borgo_Milano%29_Italy_-_%28particulate_pollution%2C_polveri_sottili%29_-_2020_01_30_%28hour_22-37%29_-_OUTdoor_and_INdoor_%28HEPA_H13_filter%29_-_first_publication_commons.wikimedia.org.webm/Display_VSON_WP6910_%28air_detector%29_-_pm2%2C5_at_Verona_%28Borgo_Milano%29_Italy_-_%28particulate_pollution%2C_polveri_sottili%29_-_2020_01_30_%28hour_22-37%29_-_OUTdoor_and_INdoor_%28HEPA_H13_filter%29_-_first_publication_commons.wikimedia.org.webm.480p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="480p.vp9.webm" data-width="586" data-height="480" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/f/f1/Display_VSON_WP6910_%28air_detector%29_-_pm2%2C5_at_Verona_%28Borgo_Milano%29_Italy_-_%28particulate_pollution%2C_polveri_sottili%29_-_2020_01_30_%28hour_22-37%29_-_OUTdoor_and_INdoor_%28HEPA_H13_filter%29_-_first_publication_commons.wikimedia.org.webm/Display_VSON_WP6910_%28air_detector%29_-_pm2%2C5_at_Verona_%28Borgo_Milano%29_Italy_-_%28particulate_pollution%2C_polveri_sottili%29_-_2020_01_30_%28hour_22-37%29_-_OUTdoor_and_INdoor_%28HEPA_H13_filter%29_-_first_publication_commons.wikimedia.org.webm.144p.mjpeg.mov" type="video/quicktime" data-transcodekey="144p.mjpeg.mov" data-width="176" data-height="144" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/f/f1/Display_VSON_WP6910_%28air_detector%29_-_pm2%2C5_at_Verona_%28Borgo_Milano%29_Italy_-_%28particulate_pollution%2C_polveri_sottili%29_-_2020_01_30_%28hour_22-37%29_-_OUTdoor_and_INdoor_%28HEPA_H13_filter%29_-_first_publication_commons.wikimedia.org.webm/Display_VSON_WP6910_%28air_detector%29_-_pm2%2C5_at_Verona_%28Borgo_Milano%29_Italy_-_%28particulate_pollution%2C_polveri_sottili%29_-_2020_01_30_%28hour_22-37%29_-_OUTdoor_and_INdoor_%28HEPA_H13_filter%29_-_first_publication_commons.wikimedia.org.webm.240p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="240p.vp9.webm" data-width="294" data-height="240" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/f/f1/Display_VSON_WP6910_%28air_detector%29_-_pm2%2C5_at_Verona_%28Borgo_Milano%29_Italy_-_%28particulate_pollution%2C_polveri_sottili%29_-_2020_01_30_%28hour_22-37%29_-_OUTdoor_and_INdoor_%28HEPA_H13_filter%29_-_first_publication_commons.wikimedia.org.webm/Display_VSON_WP6910_%28air_detector%29_-_pm2%2C5_at_Verona_%28Borgo_Milano%29_Italy_-_%28particulate_pollution%2C_polveri_sottili%29_-_2020_01_30_%28hour_22-37%29_-_OUTdoor_and_INdoor_%28HEPA_H13_filter%29_-_first_publication_commons.wikimedia.org.webm.360p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="360p.vp9.webm" data-width="440" data-height="360" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/f/f1/Display_VSON_WP6910_%28air_detector%29_-_pm2%2C5_at_Verona_%28Borgo_Milano%29_Italy_-_%28particulate_pollution%2C_polveri_sottili%29_-_2020_01_30_%28hour_22-37%29_-_OUTdoor_and_INdoor_%28HEPA_H13_filter%29_-_first_publication_commons.wikimedia.org.webm/Display_VSON_WP6910_%28air_detector%29_-_pm2%2C5_at_Verona_%28Borgo_Milano%29_Italy_-_%28particulate_pollution%2C_polveri_sottili%29_-_2020_01_30_%28hour_22-37%29_-_OUTdoor_and_INdoor_%28HEPA_H13_filter%29_-_first_publication_commons.wikimedia.org.webm.360p.webm" type="video/webm; codecs="vp8, vorbis"" data-transcodekey="360p.webm" data-width="440" data-height="360" /></video></span><figcaption>HEPA filter effect inside home <a href="/wiki/Heating,_ventilation,_and_air_conditioning" title="Heating, ventilation, and air conditioning">HVAC</a> system: without (OUTdoor) and with filter (INdoor)</figcaption></figure> <p><a href="/wiki/Heating,_ventilation,_and_air_conditioning" title="Heating, ventilation, and air conditioning">Heating, ventilation, and air conditioning</a> (HVAC)<sup id="cite_ref-34" class="reference"><a href="#cite_note-34"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> is technology that uses air filters, such as HEPA filters, to remove pollutants from the air either indoors or in vehicles. Pollutants include smoke, viruses, <a href="/wiki/Powder" title="Powder">powders</a>, etc., and can originate either outside or inside. HVAC is used to provide environmental comfort and in <a href="/wiki/Pollution" title="Pollution">polluted</a> cities to maintain health.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (February 2021)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading3"><h3 id="Vehicles">Vehicles</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=HEPA&action=edit&section=13" title="Edit section: Vehicles"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading4"><h4 id="Airlines">Airlines</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=HEPA&action=edit&section=14" title="Edit section: Airlines"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Modern airliners use HEPA filters to reduce the spread of airborne <a href="/wiki/Pathogen" title="Pathogen">pathogens</a> in recirculated air. Critics have expressed concern about the effectiveness and state of repair of air filtering systems, since they think that much of the air in an airplane cabin is recirculated. Almost all of the air in a <a href="/wiki/Pressurization" title="Pressurization">pressurized</a> aircraft is, in fact, brought in from the outside, circulated through the cabin and then exhausted through outflow valves in the rear of the aircraft.<sup id="cite_ref-35" class="reference"><a href="#cite_note-35"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup> About 40 percent of the cabin's air goes through a HEPA filter and the other 60 percent comes from outside the plane. Certified air filters block and capture 99.97 percent of airborne particles.<sup id="cite_ref-36" class="reference"><a href="#cite_note-36"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading4"><h4 id="Motor_vehicles">Motor vehicles</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=HEPA&action=edit&section=15" title="Edit section: Motor vehicles"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In 2016, it was announced that the <a href="/wiki/Tesla_Model_X" title="Tesla Model X">Tesla Model X</a> would have the world's first HEPA-grade filter in a Tesla car.<sup id="cite_ref-37" class="reference"><a href="#cite_note-37"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup> Following the release of the Model X, Tesla has updated the <a href="/wiki/Tesla_Model_S" title="Tesla Model S">Model S</a> to also have an optional HEPA air filter.<sup id="cite_ref-38" class="reference"><a href="#cite_note-38"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="History">History</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=HEPA&action=edit&section=16" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The idea behind the development of the HEPA filter was born from <a href="/wiki/Gas_mask" title="Gas mask">gas masks</a> worn by soldiers fighting in World War II. A piece of paper found inserted into a German gas mask had a remarkably high capture efficiency for chemical smoke. The British Army <a href="/wiki/Chemical_Corps" title="Chemical Corps">Chemical Corps</a> duplicated this and began to manufacture it in large quantities for their own service gas masks. They needed another solution for operational headquarters, where individual gas masks were impractical. The Army Chemical Corps developed a combination mechanical blower and air purifier unit, which incorporated cellulose-asbestos paper in a deeply-pleated form with spacers between the pleats. It was referred to as an "absolute" air filter and laid the groundwork for further research to come in developing the HEPA filter.<sup id="cite_ref-39" class="reference"><a href="#cite_note-39"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup> </p><p>The next phase of the HEPA filter was designed in the 1940s and was used in the <a href="/wiki/Manhattan_Project" title="Manhattan Project">Manhattan Project</a> to prevent the spread of airborne <a href="/wiki/Radioactive_decay" title="Radioactive decay">radioactive</a> contaminants.<sup id="cite_ref-40" class="reference"><a href="#cite_note-40"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup> The US Army Chemical Corps and National Defense Research Committee needed to develop a filter suitable for removing radioactive materials from the air. The Army Chemical Corps asked Nobel Laureate <a href="/wiki/Irving_Langmuir" title="Irving Langmuir">Irving Langmuir</a> to recommend filter test methods and other general recommendations for creating the material to filter out these radioactive particles. He identified 0.3 micron size particles to be the "most penetrating size"—the most difficult and concerning.<sup id="cite_ref-41" class="reference"><a href="#cite_note-41"><span class="cite-bracket">[</span>41<span class="cite-bracket">]</span></a></sup> </p><p>It was commercialized in the 1950s, and the original term became a registered trademark and later a generic trademark for highly efficient filters.<sup id="cite_ref-:0_14-1" class="reference"><a href="#cite_note-:0-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </p><p>Over the decades filters have evolved to satisfy the higher and higher demands for air quality in various high technology industries, such as aerospace, pharmaceutical industry, hospitals, health care, nuclear fuels, nuclear power, and <a href="/wiki/Integrated_circuit" title="Integrated circuit">integrated circuit</a> fabrication.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2024)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=HEPA&action=edit&section=17" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Air_purifier" title="Air purifier">Air purifier</a> – Device that removes contaminants from the air in a room</li> <li><a href="/wiki/Clean_air_delivery_rate" title="Clean air delivery rate">Clean air delivery rate</a> – Filtration efficacy measurement</li> <li><a href="/wiki/Cleanroom" title="Cleanroom">Cleanroom</a> – Dust-free room for research or production</li> <li><a href="/wiki/Electrostatic_precipitator" title="Electrostatic precipitator">Electrostatic precipitator</a> – Filtration device – trap particles with high voltage</li> <li><a href="/wiki/Hypoallergenic_vacuum_cleaner" title="Hypoallergenic vacuum cleaner">Hypoallergenic vacuum cleaner</a> – vacuum cleaner with high efficiency air filter</li> <li><a href="/wiki/Minimum_efficiency_reporting_value" title="Minimum efficiency reporting value">Minimum efficiency reporting value</a> – Measurement scale for the effectiveness of air filters (MERV)</li> <li><a href="/wiki/Respirator" title="Respirator">Respirator</a> – Device worn to protect the user from inhaling contaminants</li> <li><a href="/wiki/ULPA" class="mw-redirect" title="ULPA">ULPA</a> – Removes 99.999% of dust, pollen, mold, bacteria, and particles larger than 120 nm (0.12 μm)</li> <li><a href="/wiki/Ultraviolet_germicidal_irradiation" title="Ultraviolet germicidal irradiation">Ultraviolet germicidal irradiation</a> – Disinfection method using ultraviolet light</li> <li><a href="/wiki/Corsi%E2%80%93Rosenthal_Box" title="Corsi–Rosenthal Box">Corsi–Rosenthal Box</a> – Air purifier design</li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=HEPA&action=edit&section=18" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-columns references-column-width" style="column-width: 30em;"> <ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.hepa.com/glossary">"GLOSSARY"</a>. <a href="/w/index.php?title=HEPA_Corporation&action=edit&redlink=1" class="new" title="HEPA Corporation (page does not exist)">HEPA Corporation</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20200420065929/https://www.hepa.com/glossary">Archived</a> from the original on 2020-04-20<span class="reference-accessdate">. Retrieved <span class="nowrap">2021-05-14</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=GLOSSARY&rft.pub=HEPA+Corporation&rft_id=https%3A%2F%2Fwww.hepa.com%2Fglossary&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHEPA" class="Z3988"></span></span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.thefreedictionary.com/HEPA">"HEPA"</a>. <i><a href="/wiki/The_Free_Dictionary" title="The Free Dictionary">The Free Dictionary</a></i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20200420235158/https://www.thefreedictionary.com/HEPA">Archived</a> from the original on 2020-04-20<span class="reference-accessdate">. Retrieved <span class="nowrap">2021-05-14</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=The+Free+Dictionary&rft.atitle=HEPA&rft_id=https%3A%2F%2Fwww.thefreedictionary.com%2FHEPA&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHEPA" class="Z3988"></span></span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.air-purifier-power.com/hepa-air-filter.html">"Efficiency of the HEPA air filter: HEPA filter quality and bypassing"</a>. <i>Air-Purifier-Power</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20200420070844/http://www.air-purifier-power.com/hepa-air-filter.html">Archived</a> from the original on 2020-04-20<span class="reference-accessdate">. Retrieved <span class="nowrap">2021-05-14</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Air-Purifier-Power&rft.atitle=Efficiency+of+the+HEPA+air+filter%3A+HEPA+filter+quality+and+bypassing&rft_id=http%3A%2F%2Fwww.air-purifier-power.com%2Fhepa-air-filter.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHEPA" class="Z3988"></span></span> </li> <li id="cite_note-ISO_29463-4"><span class="mw-cite-backlink">^ <a href="#cite_ref-ISO_29463_4-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-ISO_29463_4-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-ISO_29463_4-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.sis.se/api/document/preview/913826/">"INTERNATIONAL ISO STANDARD 29463-1—High-efficiency filters and filter media for removing particles in air"</a>. <a href="/wiki/International_Organization_for_Standardization" title="International Organization for Standardization">International Organization for Standardization</a>. 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Retrieved <span class="nowrap">May 16,</span> 2021</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=INTERNATIONAL+ISO+STANDARD+29463-1%E2%80%94High-efficiency+filters+and+filter+media+for+removing+particles+in+air&rft.pub=International+Organization+for+Standardization&rft.date=2011-10-15&rft_id=https%3A%2F%2Fwww.sis.se%2Fapi%2Fdocument%2Fpreview%2F913826%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHEPA" class="Z3988"></span></span> </li> <li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text">European Standard EN 1822-1:2009, "High efficiency air filters (EPA, HEPA and ULPA)", 2009</span> </li> <li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text">American Society of Mechanical Engineers, ASME AG-1a–2004, "Addenda to ASME AG-1–2003 Code on Nuclear Air and Gas Treatment", 2004</span> </li> <li id="cite_note-:1-7"><span class="mw-cite-backlink">^ <a href="#cite_ref-:1_7-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:1_7-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFBarnette" class="citation web cs1">Barnette, Sonya. <a rel="nofollow" class="external text" href="https://www.standards.doe.gov/standards-documents/3000/3020-astd-2015">"Specification for HEPA Filters Used by DOE Contractors — DOE Technical Standards Program"</a>. <i>www.standards.doe.gov</i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20200420065034/https://www.standards.doe.gov/standards-documents/3000/3020-astd-2015">Archived</a> from the original on 2020-04-20<span class="reference-accessdate">. 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Retrieved <span class="nowrap">2021-05-16</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Tesla%2C+Inc.&rft.atitle=Putting+the+Tesla+HEPA+Filter+and+Bioweapon+Defense+Mode+to+the+Test&rft.date=2016-05-02&rft_id=https%3A%2F%2Fwww.tesla.com%2Fblog%2Fputting-tesla-hepa-filter-and-bioweapon-defense-mode-to-the-test&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHEPA" class="Z3988"></span></span> </li> <li id="cite_note-38"><span class="mw-cite-backlink"><b><a href="#cite_ref-38">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFVölcker2016" class="citation news cs1">Völcker, John (2016-04-12). <a rel="nofollow" class="external text" href="https://www.greencarreports.com/news/1103380_2016-tesla-model-s-gets-styling-update-48-amp-charger-new-interior-options">"2016 Tesla Model S gets styling update, 48-amp charger, new interior options, $1,500 price increase (updated)"</a>. <i><a href="/w/index.php?title=Green_Car_Reports&action=edit&redlink=1" class="new" title="Green Car Reports (page does not exist)">Green Car Reports</a></i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210224154947/https://www.greencarreports.com/news/1103380_2016-tesla-model-s-gets-styling-update-48-amp-charger-new-interior-options">Archived</a> from the original on 2021-02-24<span class="reference-accessdate">. Retrieved <span class="nowrap">2021-05-16</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Green+Car+Reports&rft.atitle=2016+Tesla+Model+S+gets+styling+update%2C+48-amp+charger%2C+new+interior+options%2C+%241%2C500+price+increase+%28updated%29&rft.date=2016-04-12&rft.aulast=V%C3%B6lcker&rft.aufirst=John&rft_id=https%3A%2F%2Fwww.greencarreports.com%2Fnews%2F1103380_2016-tesla-model-s-gets-styling-update-48-amp-charger-new-interior-options&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHEPA" class="Z3988"></span></span> </li> <li id="cite_note-39"><span class="mw-cite-backlink"><b><a href="#cite_ref-39">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFFirst1998" class="citation journal cs1">First, Melvin W. (March 1, 1998). <a rel="nofollow" class="external text" href="https://www.liebertpub.com/doi/pdf/10.1177/109135059800300111">"HEPA Filters"</a>. <i><a href="/w/index.php?title=Journal_of_the_American_Biological_Safety_Association&action=edit&redlink=1" class="new" title="Journal of the American Biological Safety Association (page does not exist)">Journal of the American Biological Safety Association</a></i>. <b>3</b> (1). <a href="/wiki/American_Biological_Safety_Association" title="American Biological Safety Association">American Biological Safety Association</a>: <span class="nowrap">33–</span>42. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1177%2F109135059800300111">10.1177/109135059800300111</a>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1091-3505">1091-3505</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:207941359">207941359</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210516175101/https://www.liebertpub.com/doi/pdf/10.1177/109135059800300111">Archived</a> from the original on May 16, 2021<span class="reference-accessdate">. Retrieved <span class="nowrap">May 16,</span> 2021</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+the+American+Biological+Safety+Association&rft.atitle=HEPA+Filters&rft.volume=3&rft.issue=1&rft.pages=%3Cspan+class%3D%22nowrap%22%3E33-%3C%2Fspan%3E42&rft.date=1998-03-01&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A207941359%23id-name%3DS2CID&rft.issn=1091-3505&rft_id=info%3Adoi%2F10.1177%2F109135059800300111&rft.aulast=First&rft.aufirst=Melvin+W.&rft_id=https%3A%2F%2Fwww.liebertpub.com%2Fdoi%2Fpdf%2F10.1177%2F109135059800300111&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHEPA" class="Z3988"></span></span> </li> <li id="cite_note-40"><span class="mw-cite-backlink"><b><a href="#cite_ref-40">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFOgunseitanRobbins2011" class="citation book cs1">Ogunseitan, Oladele; Robbins, Paul, eds. (2011). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=XtXJzogLCecC&pg=PA13"><i>Green Health: An A-to-Z Guide</i></a>. Los Angeles: <a href="/wiki/SAGE_Publishing" class="mw-redirect" title="SAGE Publishing">SAGE Publishing</a>. p. 13. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9781412996884" title="Special:BookSources/9781412996884"><bdi>9781412996884</bdi></a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/793012578">793012578</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210517182333/https://books.google.com/books?id=XtXJzogLCecC&pg=PA13">Archived</a> from the original on 2021-05-17<span class="reference-accessdate">. Retrieved <span class="nowrap">2016-12-18</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Green+Health%3A+An+A-to-Z+Guide&rft.place=Los+Angeles&rft.pages=13&rft.pub=SAGE+Publishing&rft.date=2011&rft_id=info%3Aoclcnum%2F793012578&rft.isbn=9781412996884&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DXtXJzogLCecC%26pg%3DPA13&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHEPA" class="Z3988"></span></span> </li> <li id="cite_note-41"><span class="mw-cite-backlink"><b><a href="#cite_ref-41">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.apcfilters.com/the-history-of-hepa-filters/">"The History of HEPA Filters"</a>. <i>APC Filters</i>. November 21, 2019. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20210326084208/https://www.apcfilters.com/the-history-of-hepa-filters/">Archived</a> from the original on March 26, 2021<span class="reference-accessdate">. Retrieved <span class="nowrap">May 16,</span> 2021</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=APC+Filters&rft.atitle=The+History+of+HEPA+Filters&rft.date=2019-11-21&rft_id=https%3A%2F%2Fwww.apcfilters.com%2Fthe-history-of-hepa-filters%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHEPA" class="Z3988"></span></span> </li> </ol></div> <div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=HEPA&action=edit&section=19" title="Edit section: Further reading"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20170829125133/http://www.tsi.com/uploadedFiles/Product_Information/Literature/Application_Notes/ITI-041.pdf">TSI Application Note ITI-041: Mechanisms of Filtration for High Efficiency Fibrous Filters</a></li></ul> <style data-mw-deduplicate="TemplateStyles:r1235681985">.mw-parser-output .side-box{margin:4px 0;box-sizing:border-box;border:1px solid #aaa;font-size:88%;line-height:1.25em;background-color:var(--background-color-interactive-subtle,#f8f9fa);display:flow-root}.mw-parser-output .side-box-abovebelow,.mw-parser-output .side-box-text{padding:0.25em 0.9em}.mw-parser-output .side-box-image{padding:2px 0 2px 0.9em;text-align:center}.mw-parser-output .side-box-imageright{padding:2px 0.9em 2px 0;text-align:center}@media(min-width:500px){.mw-parser-output .side-box-flex{display:flex;align-items:center}.mw-parser-output .side-box-text{flex:1;min-width:0}}@media(min-width:720px){.mw-parser-output .side-box{width:238px}.mw-parser-output .side-box-right{clear:right;float:right;margin-left:1em}.mw-parser-output .side-box-left{margin-right:1em}}</style><style data-mw-deduplicate="TemplateStyles:r1237033735">@media print{body.ns-0 .mw-parser-output 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href="/wiki/Infiltration_(HVAC)" title="Infiltration (HVAC)">Infiltration</a></li> <li><a href="/wiki/Latent_heat" title="Latent heat">Latent heat</a></li> <li><a href="/wiki/Noise_control" title="Noise control">Noise control</a></li> <li><a href="/wiki/Outgassing" title="Outgassing">Outgassing</a></li> <li><a href="/wiki/Particulates" title="Particulates">Particulates</a></li> <li><a href="/wiki/Psychrometrics" title="Psychrometrics">Psychrometrics</a></li> <li><a href="/wiki/Sensible_heat" title="Sensible heat">Sensible heat</a></li> <li><a href="/wiki/Stack_effect" title="Stack effect">Stack effect</a></li> <li><a href="/wiki/Thermal_comfort" title="Thermal comfort">Thermal comfort</a></li> <li><a href="/wiki/Thermal_destratification" title="Thermal destratification">Thermal destratification</a></li> <li><a href="/wiki/Thermal_mass" title="Thermal mass">Thermal mass</a></li> <li><a href="/wiki/Thermodynamics" title="Thermodynamics">Thermodynamics</a></li> <li><a href="/wiki/Vapour_pressure_of_water" title="Vapour pressure of water">Vapour pressure of water</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Technology</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Absorption-compression_heat_pump" title="Absorption-compression heat pump">Absorption-compression heat pump</a></li> <li><a href="/wiki/Absorption_refrigerator" title="Absorption refrigerator">Absorption refrigerator</a></li> <li><a href="/wiki/Air_barrier" title="Air barrier">Air barrier</a></li> <li><a href="/wiki/Air_conditioning" title="Air conditioning">Air conditioning</a></li> <li><a href="/wiki/Antifreeze" title="Antifreeze">Antifreeze</a></li> <li><a href="/wiki/Automobile_air_conditioning" class="mw-redirect" title="Automobile air conditioning">Automobile air conditioning</a></li> <li><a href="/wiki/Autonomous_building" title="Autonomous building">Autonomous building</a></li> <li><a href="/wiki/Building_insulation_material" title="Building insulation material">Building insulation materials</a></li> <li><a href="/wiki/Central_heating" title="Central heating">Central heating</a></li> <li><a href="/wiki/Central_solar_heating" title="Central solar heating">Central solar heating</a></li> <li><a href="/wiki/Chilled_beam" title="Chilled beam">Chilled beam</a></li> <li><a href="/wiki/Chilled_water" title="Chilled water">Chilled water</a></li> <li><a href="/wiki/Constant_air_volume" title="Constant air volume">Constant air volume</a> (CAV)</li> <li><a href="/wiki/Coolant" title="Coolant">Coolant</a></li> <li><a href="/wiki/Cross_ventilation" title="Cross ventilation">Cross ventilation</a></li> <li><a href="/wiki/Dedicated_outdoor_air_system" title="Dedicated outdoor air system">Dedicated outdoor air system</a> (DOAS)</li> <li><a href="/wiki/Deep_water_source_cooling" title="Deep water source cooling">Deep water source cooling</a></li> <li><a href="/wiki/Demand_controlled_ventilation" title="Demand controlled ventilation">Demand controlled ventilation</a> (DCV)</li> <li><a href="/wiki/Displacement_ventilation" title="Displacement ventilation">Displacement ventilation</a></li> <li><a href="/wiki/District_cooling" title="District cooling">District cooling</a></li> <li><a href="/wiki/District_heating" title="District heating">District heating</a></li> <li><a href="/wiki/Electric_heating" title="Electric heating">Electric heating</a></li> <li><a href="/wiki/Energy_recovery_ventilation" class="mw-redirect" title="Energy recovery ventilation">Energy recovery ventilation</a> (ERV)</li> <li><a href="/wiki/Firestop" title="Firestop">Firestop</a></li> <li><a href="/wiki/Forced-air" title="Forced-air">Forced-air</a></li> <li><a href="/wiki/Forced-air_gas" title="Forced-air gas">Forced-air gas</a></li> <li><a href="/wiki/Free_cooling" title="Free cooling">Free cooling</a></li> <li><a href="/wiki/Heat_recovery_ventilation" title="Heat recovery ventilation">Heat recovery ventilation</a> (HRV)</li> <li><a href="/wiki/Hybrid_heat" title="Hybrid heat">Hybrid heat</a></li> <li><a href="/wiki/Hydronics" title="Hydronics">Hydronics</a></li> <li><a href="/wiki/Ice_storage_air_conditioning" title="Ice storage air conditioning">Ice storage air conditioning</a></li> <li><a href="/wiki/Kitchen_ventilation" title="Kitchen ventilation">Kitchen ventilation</a></li> <li><a href="/wiki/Mixed-mode_ventilation" title="Mixed-mode ventilation">Mixed-mode ventilation</a></li> <li><a href="/wiki/Microgeneration" title="Microgeneration">Microgeneration</a></li> <li><a href="/wiki/Passive_cooling" title="Passive cooling">Passive cooling</a></li> <li><a href="/wiki/Passive_daytime_radiative_cooling" title="Passive daytime radiative cooling">Passive daytime radiative cooling</a></li> <li><a href="/wiki/Passive_house" title="Passive house">Passive house</a></li> <li><a href="/wiki/Passive_ventilation" title="Passive ventilation">Passive ventilation</a></li> <li><a href="/wiki/Radiant_heating_and_cooling" title="Radiant heating and cooling">Radiant heating and cooling</a></li> <li><a href="/wiki/Radiant_cooling" class="mw-redirect" title="Radiant cooling">Radiant cooling</a></li> <li><a href="/wiki/Radiant_heating" class="mw-redirect" title="Radiant heating">Radiant heating</a></li> <li><a href="/wiki/Radon_mitigation" title="Radon mitigation">Radon mitigation</a></li> <li><a href="/wiki/Refrigeration" title="Refrigeration">Refrigeration</a></li> <li><a href="/wiki/Renewable_heat" title="Renewable heat">Renewable heat</a></li> <li><a href="/wiki/Room_air_distribution" title="Room air distribution">Room air distribution</a></li> <li><a href="/wiki/Solar_air_heat" title="Solar air heat">Solar air heat</a></li> <li><a href="/wiki/Solar_combisystem" title="Solar combisystem">Solar combisystem</a></li> <li><a href="/wiki/Solar_cooling" class="mw-redirect" title="Solar cooling">Solar cooling</a></li> <li><a href="/wiki/Solar_heating" class="mw-redirect" title="Solar heating">Solar heating</a></li> <li><a href="/wiki/Thermal_insulation" title="Thermal insulation">Thermal insulation</a></li> <li><a href="/wiki/Thermosiphon" title="Thermosiphon">Thermosiphon</a></li> <li><a href="/wiki/Underfloor_air_distribution" title="Underfloor air distribution">Underfloor air distribution</a></li> <li><a href="/wiki/Underfloor_heating" title="Underfloor heating">Underfloor heating</a></li> <li><a href="/wiki/Vapor_barrier" title="Vapor barrier">Vapor barrier</a></li> <li><a href="/wiki/Vapor-compression_refrigeration" title="Vapor-compression refrigeration">Vapor-compression refrigeration</a> (VCRS)</li> <li><a href="/wiki/Variable_air_volume" title="Variable air volume">Variable air volume</a> (VAV)</li> <li><a href="/wiki/Variable_refrigerant_flow" title="Variable refrigerant flow">Variable refrigerant flow</a> (VRF)</li> <li><a href="/wiki/Ventilation_(architecture)" title="Ventilation (architecture)">Ventilation</a></li> <li><a href="/wiki/Water_heat_recycling" title="Water heat recycling">Water heat recycling</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Components</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Air_conditioner_inverter" class="mw-redirect" title="Air conditioner inverter">Air conditioner inverter</a></li> <li><a href="/wiki/Air_door" title="Air door">Air door</a></li> <li><a href="/wiki/Air_filter" title="Air filter">Air filter</a></li> <li><a href="/wiki/Air_handler" title="Air handler">Air handler</a></li> <li><a href="/wiki/Air_ioniser" title="Air ioniser">Air ionizer</a></li> <li><a href="/wiki/Air-mixing_plenum" title="Air-mixing plenum">Air-mixing plenum</a></li> <li><a href="/wiki/Air_purifier" title="Air purifier">Air purifier</a></li> <li><a href="/wiki/Air_source_heat_pump" title="Air source heat pump">Air source heat pump</a></li> <li><a href="/wiki/Attic_fan" title="Attic fan">Attic fan</a></li> <li><a href="/wiki/Automatic_balancing_valve" title="Automatic balancing valve">Automatic balancing valve</a></li> <li><a href="/wiki/Back_boiler" title="Back boiler">Back boiler</a></li> <li><a href="/wiki/Barrier_pipe" title="Barrier pipe">Barrier pipe</a></li> <li><a href="/wiki/Blast_damper" title="Blast damper">Blast damper</a></li> <li><a href="/wiki/Boiler" title="Boiler">Boiler</a></li> <li><a href="/wiki/Centrifugal_fan" title="Centrifugal fan">Centrifugal fan</a></li> <li><a href="/wiki/Ceramic_heater" title="Ceramic heater">Ceramic heater</a></li> <li><a href="/wiki/Chiller" title="Chiller">Chiller</a></li> <li><a href="/wiki/Condensate_pump" title="Condensate pump">Condensate pump</a></li> <li><a href="/wiki/Condenser_(heat_transfer)" title="Condenser (heat transfer)">Condenser</a></li> <li><a href="/wiki/Condensing_boiler" title="Condensing boiler">Condensing boiler</a></li> <li><a href="/wiki/Convection_heater" title="Convection heater">Convection heater</a></li> <li><a href="/wiki/Compressor" title="Compressor">Compressor</a></li> <li><a href="/wiki/Cooling_tower" title="Cooling tower">Cooling tower</a></li> <li><a href="/wiki/Damper_(flow)" title="Damper (flow)">Damper</a></li> <li><a href="/wiki/Dehumidifier" title="Dehumidifier">Dehumidifier</a></li> <li><a href="/wiki/Duct_(flow)" title="Duct (flow)">Duct</a></li> <li><a href="/wiki/Economizer" title="Economizer">Economizer</a></li> <li><a href="/wiki/Electrostatic_precipitator" title="Electrostatic precipitator">Electrostatic precipitator</a></li> <li><a href="/wiki/Evaporative_cooler" title="Evaporative cooler">Evaporative cooler</a></li> <li><a href="/wiki/Evaporator" title="Evaporator">Evaporator</a></li> <li><a href="/wiki/Exhaust_hood" class="mw-redirect" title="Exhaust hood">Exhaust hood</a></li> <li><a href="/wiki/Expansion_tank" title="Expansion tank">Expansion tank</a></li> <li><a href="/wiki/Fan_(machine)" title="Fan (machine)">Fan</a></li> <li><a href="/wiki/Fan_coil_unit" title="Fan coil unit">Fan coil unit</a></li> <li><a href="/wiki/Fan_filter_unit" title="Fan filter unit">Fan filter unit</a></li> <li><a href="/wiki/Fan_heater" title="Fan heater">Fan heater</a></li> <li><a href="/wiki/Fire_damper" title="Fire damper">Fire damper</a></li> <li><a href="/wiki/Fireplace" title="Fireplace">Fireplace</a></li> <li><a href="/wiki/Fireplace_insert" title="Fireplace insert">Fireplace insert</a></li> <li><a href="/wiki/Freeze_stat" title="Freeze stat">Freeze stat</a></li> <li><a href="/wiki/Flue" title="Flue">Flue</a></li> <li><a href="/wiki/Freon" title="Freon">Freon</a></li> <li><a href="/wiki/Fume_hood" title="Fume hood">Fume hood</a></li> <li><a href="/wiki/Furnace_(house_heating)" class="mw-redirect" title="Furnace (house heating)">Furnace</a></li> <li><a href="/wiki/Gas_compressor" class="mw-redirect" title="Gas compressor">Gas compressor</a></li> <li><a href="/wiki/Gas_heater" title="Gas heater">Gas heater</a></li> <li><a href="/wiki/Gasoline_heater" title="Gasoline heater">Gasoline heater</a></li> <li><a href="/wiki/Grease_duct" title="Grease duct">Grease duct</a></li> <li><a href="/wiki/Grille_(architecture)" title="Grille (architecture)">Grille</a></li> <li><a href="/wiki/Ground-coupled_heat_exchanger" title="Ground-coupled heat exchanger">Ground-coupled heat exchanger</a></li> <li><a href="/wiki/Ground_source_heat_pump" title="Ground source heat pump">Ground source heat pump</a></li> <li><a href="/wiki/Heat_exchanger" title="Heat exchanger">Heat exchanger</a></li> <li><a href="/wiki/Heat_pipe" title="Heat pipe">Heat pipe</a></li> <li><a href="/wiki/Heat_pump" title="Heat pump">Heat pump</a></li> <li><a href="/wiki/Heating_film" title="Heating film">Heating film</a></li> <li><a href="/wiki/Heating_system" title="Heating system">Heating system</a></li> <li><a class="mw-selflink selflink">HEPA</a></li> <li><a href="/wiki/High_efficiency_glandless_circulating_pump" title="High efficiency glandless circulating pump">High efficiency glandless circulating pump</a></li> <li><a href="/wiki/High-pressure_cut-off_switch" class="mw-redirect" title="High-pressure cut-off switch">High-pressure cut-off switch</a></li> <li><a href="/wiki/Humidifier" title="Humidifier">Humidifier</a></li> <li><a href="/wiki/Infrared_heater" title="Infrared heater">Infrared heater</a></li> <li><a href="/wiki/Inverter_compressor" title="Inverter compressor">Inverter compressor</a></li> <li><a href="/wiki/Kerosene_heater" title="Kerosene heater">Kerosene heater</a></li> <li><a href="/wiki/Louver" title="Louver">Louver</a></li> <li><a href="/wiki/Mechanical_room" title="Mechanical room">Mechanical room</a></li> <li><a href="/wiki/Oil_heater" title="Oil heater">Oil heater</a></li> <li><a href="/wiki/Packaged_terminal_air_conditioner" title="Packaged terminal air conditioner">Packaged terminal air conditioner</a></li> <li><a href="/wiki/Plenum_space" title="Plenum space">Plenum space</a></li> <li><a href="/wiki/Pressurisation_ductwork" title="Pressurisation ductwork">Pressurisation ductwork</a></li> <li><a href="/wiki/Process_duct_work" title="Process duct work">Process duct work</a></li> <li><a href="/wiki/Radiator_(heating)" title="Radiator (heating)">Radiator</a></li> <li><a href="/wiki/Radiator_reflector" title="Radiator reflector">Radiator reflector</a></li> <li><a href="/wiki/Recuperator" title="Recuperator">Recuperator</a></li> <li><a href="/wiki/Refrigerant" title="Refrigerant">Refrigerant</a></li> <li><a href="/wiki/Register_(air_and_heating)" title="Register (air and heating)">Register</a></li> <li><a href="/wiki/Reversing_valve" title="Reversing valve">Reversing valve</a></li> <li><a href="/wiki/Run-around_coil" title="Run-around coil">Run-around coil</a></li> <li><a href="/wiki/Sail_switch" title="Sail switch">Sail switch</a></li> <li><a href="/wiki/Scroll_compressor" title="Scroll compressor">Scroll compressor</a></li> <li><a href="/wiki/Solar_chimney" title="Solar chimney">Solar chimney</a></li> <li><a href="/wiki/Solar-assisted_heat_pump" title="Solar-assisted heat pump">Solar-assisted heat pump</a></li> <li><a href="/wiki/Space_heater" title="Space heater">Space heater</a></li> <li><a href="/wiki/Smoke_canopy" title="Smoke canopy">Smoke canopy</a></li> <li><a href="/wiki/Smoke_damper" title="Smoke damper">Smoke damper</a></li> <li><a href="/wiki/Smoke_exhaust_ductwork" title="Smoke exhaust ductwork">Smoke exhaust ductwork</a></li> <li><a href="/wiki/Thermal_expansion_valve" title="Thermal expansion valve">Thermal expansion valve</a></li> <li><a href="/wiki/Thermal_wheel" title="Thermal wheel">Thermal wheel</a></li> <li><a href="/wiki/Thermostatic_radiator_valve" title="Thermostatic radiator valve">Thermostatic radiator valve</a></li> <li><a href="/wiki/Trickle_vent" title="Trickle vent">Trickle vent</a></li> <li><a href="/wiki/Trombe_wall" title="Trombe wall">Trombe wall</a></li> <li><a href="/wiki/TurboSwing" title="TurboSwing">TurboSwing</a></li> <li><a href="/wiki/Turning_vanes_(HVAC)" title="Turning vanes (HVAC)">Turning vanes</a></li> <li><a href="/wiki/Ultra-low_particulate_air" title="Ultra-low particulate air">Ultra-low particulate air</a> (ULPA)</li> <li><a href="/wiki/Whole-house_fan" title="Whole-house fan">Whole-house fan</a></li> <li><a href="/wiki/Windcatcher" title="Windcatcher">Windcatcher</a></li> <li><a href="/wiki/Wood-burning_stove" title="Wood-burning stove">Wood-burning stove</a></li> <li><a href="/wiki/Zone_valve" title="Zone valve">Zone valve</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Measurement<br />and control</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Air_flow_meter" title="Air flow meter">Air flow meter</a></li> <li><a href="/wiki/Aquastat" title="Aquastat">Aquastat</a></li> <li><a href="/wiki/BACnet" title="BACnet">BACnet</a></li> <li><a href="/wiki/Blower_door" title="Blower door">Blower door</a></li> <li><a href="/wiki/Building_automation" title="Building automation">Building automation</a></li> <li><a href="/wiki/Carbon_dioxide_sensor" title="Carbon dioxide sensor">Carbon dioxide sensor</a></li> <li><a href="/wiki/Clean_air_delivery_rate" title="Clean air delivery rate">Clean air delivery rate</a> (CADR)</li> <li><a href="/wiki/Control_valve" title="Control valve">Control valve</a></li> <li><a href="/wiki/Gas_detector" title="Gas detector">Gas detector</a></li> <li><a href="/wiki/Home_energy_monitor" title="Home energy monitor">Home energy monitor</a></li> <li><a href="/wiki/Humidistat" title="Humidistat">Humidistat</a></li> <li><a href="/wiki/HVAC_control_system" title="HVAC control system">HVAC control system</a></li> <li><a href="/wiki/Infrared_thermometer" title="Infrared thermometer">Infrared thermometer</a></li> <li><a href="/wiki/Intelligent_buildings" class="mw-redirect" title="Intelligent buildings">Intelligent buildings</a></li> <li><a href="/wiki/LonWorks" title="LonWorks">LonWorks</a></li> <li><a href="/wiki/Minimum_efficiency_reporting_value" title="Minimum efficiency reporting value">Minimum efficiency reporting value</a> (MERV)</li> <li><a href="/wiki/Normal_temperature_and_pressure" class="mw-redirect" title="Normal temperature and pressure">Normal temperature and pressure</a> (NTP)</li> <li><a href="/wiki/OpenTherm" title="OpenTherm">OpenTherm</a></li> <li><a href="/wiki/Programmable_communicating_thermostat" title="Programmable communicating thermostat">Programmable communicating thermostat</a></li> <li><a href="/wiki/Programmable_thermostat" title="Programmable thermostat">Programmable thermostat</a></li> <li><a href="/wiki/Psychrometrics" title="Psychrometrics">Psychrometrics</a></li> <li><a href="/wiki/Room_temperature" title="Room temperature">Room temperature</a></li> <li><a href="/wiki/Smart_thermostat" title="Smart thermostat">Smart thermostat</a></li> <li><a href="/wiki/Standard_temperature_and_pressure" title="Standard temperature and pressure">Standard temperature and pressure</a> (STP)</li> <li><a href="/wiki/Thermographic_camera" class="mw-redirect" title="Thermographic camera">Thermographic camera</a></li> <li><a href="/wiki/Thermostat" title="Thermostat">Thermostat</a></li> <li><a href="/wiki/Thermostatic_radiator_valve" title="Thermostatic radiator valve">Thermostatic radiator valve</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Professions,<br />trades,<br />and services</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Architectural_acoustics" title="Architectural acoustics">Architectural acoustics</a></li> <li><a href="/wiki/Architectural_engineering" title="Architectural engineering">Architectural engineering</a></li> <li><a href="/wiki/Architectural_technologist" title="Architectural technologist">Architectural technologist</a></li> <li><a href="/wiki/Building_services_engineering" title="Building services engineering">Building services engineering</a></li> <li><a href="/wiki/Building_information_modeling" title="Building information modeling">Building information modeling</a> (BIM)</li> <li><a href="/wiki/Deep_energy_retrofit" title="Deep energy retrofit">Deep energy retrofit</a></li> <li><a href="/wiki/Duct_cleaning" class="mw-redirect" title="Duct cleaning">Duct cleaning</a></li> <li><a href="/wiki/Duct_leakage_testing" title="Duct leakage testing">Duct leakage testing</a></li> <li><a href="/wiki/Environmental_engineering" title="Environmental engineering">Environmental engineering</a></li> <li><a href="/wiki/Hydronic_balancing" title="Hydronic balancing">Hydronic balancing</a></li> <li><a href="/wiki/Kitchen_exhaust_cleaning" title="Kitchen exhaust cleaning">Kitchen exhaust cleaning</a></li> <li><a href="/wiki/Mechanical_engineering" title="Mechanical engineering">Mechanical engineering</a></li> <li><a href="/wiki/Mechanical,_electrical,_and_plumbing" title="Mechanical, electrical, and plumbing">Mechanical, electrical, and plumbing</a></li> <li><a href="/wiki/Mold_growth,_assessment,_and_remediation" class="mw-redirect" title="Mold growth, assessment, and remediation">Mold growth, assessment, and remediation</a></li> <li><a href="/wiki/Refrigerant_reclamation" title="Refrigerant reclamation">Refrigerant reclamation</a></li> <li><a href="/wiki/Testing,_adjusting,_balancing" title="Testing, adjusting, balancing">Testing, adjusting, balancing</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Industry <br />organizations</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Air_Conditioning,_Heating_and_Refrigeration_Institute" title="Air Conditioning, Heating and Refrigeration Institute">AHRI</a></li> <li><a href="/wiki/Air_Movement_and_Control_Association" title="Air Movement and Control Association">AMCA</a></li> <li><a href="/wiki/ASHRAE" title="ASHRAE">ASHRAE</a></li> <li><a href="/wiki/ASTM_International" title="ASTM International">ASTM International</a></li> <li><a href="/wiki/Building_Research_Establishment" title="Building Research Establishment">BRE</a></li> <li><a href="/wiki/BSRIA" title="BSRIA">BSRIA</a></li> <li><a href="/wiki/Chartered_Institution_of_Building_Services_Engineers" title="Chartered Institution of Building Services Engineers">CIBSE</a></li> <li><a href="/wiki/Institute_of_Refrigeration" title="Institute of Refrigeration">Institute of Refrigeration</a></li> <li><a href="/wiki/International_Institute_of_Refrigeration" title="International Institute of Refrigeration">IIR</a></li> <li><a href="/wiki/Leadership_in_Energy_and_Environmental_Design" class="mw-redirect" title="Leadership in Energy and Environmental Design">LEED</a></li> <li><a href="/wiki/Sheet_Metal_and_Air_Conditioning_Contractors%27_National_Association" title="Sheet Metal and Air Conditioning Contractors' National Association">SMACNA</a></li> <li><a href="/wiki/Uniform_Mechanical_Code" title="Uniform Mechanical Code">UMC</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Health and safety</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Indoor_air_quality" title="Indoor air quality">Indoor air quality</a> (IAQ)</li> <li><a href="/wiki/Passive_smoking" title="Passive smoking">Passive smoking</a></li> <li><a href="/wiki/Sick_building_syndrome" title="Sick building syndrome">Sick building syndrome</a> (SBS)</li> <li><a href="/wiki/Volatile_organic_compound" title="Volatile organic compound">Volatile organic compound</a> (VOC)</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">See also</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0;text-align: middle;"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/ASHRAE_Handbook" title="ASHRAE Handbook">ASHRAE Handbook</a></li> <li><a href="/wiki/Building_science" title="Building science">Building science</a></li> <li><a href="/wiki/Fireproofing" title="Fireproofing">Fireproofing</a></li> <li><a href="/wiki/Glossary_of_HVAC_terms" title="Glossary of HVAC terms">Glossary of HVAC terms</a></li> <li><a href="/wiki/Warm_Spaces" title="Warm Spaces">Warm Spaces</a></li> <li><a href="/wiki/World_Refrigeration_Day" title="World Refrigeration Day">World Refrigeration Day</a></li> <li><a href="/wiki/Template:Fire_protection" title="Template:Fire protection">Template:Fire protection</a></li> <li><a href="/wiki/Template:Home_automation" title="Template:Home automation">Template:Home automation</a></li> <li><a href="/wiki/Template:Solar_energy" title="Template:Solar energy">Template:Solar energy</a></li></ul> </div></td></tr></tbody></table></div>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?useformat=desktop&type=1x1&usesul3=0" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" href="https://en.wikipedia.org/w/index.php?title=HEPA&oldid=1276520743">https://en.wikipedia.org/w/index.php?title=HEPA&oldid=1276520743</a>"</div></div> <div id="catlinks" class="catlinks" data-mw="interface"><div id="mw-normal-catlinks" class="mw-normal-catlinks"><a href="/wiki/Help:Category" title="Help:Category">Categories</a>: <ul><li><a href="/wiki/Category:Building_biology" title="Category:Building 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