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href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//ru'><div title='俄' class='sprite-isprt-web-ru flag-ru'></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//hk'><div title='繁体中文' class='sprite-isprt-web-hk flag-zh-TW'></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//fr'><div title='法国人' class='sprite-isprt-web-fr flag-fr'></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//pl'><div title='Polish' class='sprite-isprt-web-pl flag-pl'></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//de'><div title='German' class='sprite-isprt-web-de flag-de'></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//pt'><div title='Portuguese' class='sprite-isprt-web-br flag-pt'></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//vn'><div title='Vietnamese' class='sprite-isprt-web-vn flag-vi'></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//it'><div title='Italian' class='sprite-isprt-web-it flag-it'>🇮🇹</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//id'><div title='Indonesian' class='sprite-isprt-web-id flag-id'>🇮🇩</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//nl'><div title='Dutch' class='sprite-isprt-web-nl flag-nl'>🇳🇱</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//fa'><div title='Persian' class='sprite-isprt-web-ir flag-fa'>🇮🇷</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//th'><div title='Thai' class='sprite-isprt-web-th flag-th'>🇹🇭</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//hu'><div title='Hungarian' class='sprite-isprt-web-hu flag-hu'>🇭🇺</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//el'><div title='Greek' class='sprite-isprt-web-gr flag-el'>🇬🇷</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//ro'><div title='Romanian' class='sprite-isprt-web-ro flag-ro'>🇷🇴</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//bg'><div title='Bulgarian' class='sprite-isprt-web-bg flag-bg'>🇧🇬</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//ur'><div title='Urdu' class='sprite-isprt-web-pk flag-ur'>🇵🇰</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//hi'><div title='Hindi' class='sprite-isprt-web-in flag-hi'>🇮🇳</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//ar'><div title='Arabic' class='sprite-isprt-web-ae flag-ar'>🇦🇪</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//sr'><div title='Serbian' class='sprite-isprt-web-rs flag-sr'>🇷🇸</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//bn'><div title='Bangla' class='sprite-isprt-web-bd flag-bn'>🇧🇩</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//bs'><div title='Bosnian' class='sprite-isprt-web-ba flag-bs'>🇧🇦</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//hr'><div title='Croatian' class='sprite-isprt-web-hr flag-hr'>🇭🇷</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//tr'><div title='Turkish' class='sprite-isprt-web-tr flag-tr'>🇹🇷</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//uk'><div title='Ukrainian' class='sprite-isprt-web-ua flag-uk'>🇺🇦</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//cs'><div title='Czech' class='sprite-isprt-web-cz flag-cs'>🇨🇿</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//be'><div title='Belarusian' class='sprite-isprt-web-by flag-be'>🇧🇾</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//km'><div title='Khmer' class='sprite-isprt-web-kh flag-km'>🇰🇭</div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//lo'><div title='Lao' class='sprite-isprt-web-la flag-lo'>🇱🇦</div></a></div><div id='hdrlang-navigation'><div id='hdrlang-navigation-inner' class='hdrlang-navigation'><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings/' class='lang-en'><div class='item'><div class='flag sprite-isprt-web-gb'></div><span class='name'>英语 <span>- English</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//cn' class='lang-zh-CN'><div class='item'><div class='flag sprite-isprt-web-cn'></div><span class='name'>简体中文</span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//jp' class='lang-ja'><div class='item'><div class='flag sprite-isprt-web-jp'></div><span class='name'>日本</span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//es' class='lang-es'><div class='item'><div class='flag sprite-isprt-web-es'></div><span class='name'>西班牙人 <span>- español</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//kr' class='lang-ko'><div class='item'><div class='flag sprite-isprt-web-kr'></div><span class='name'>韩国 <span>- 한국의</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//ru' class='lang-ru'><div class='item'><div class='flag sprite-isprt-web-ru'></div><span class='name'>俄 <span>- русский</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//hk' class='lang-zh-TW'><div class='item'><div class='flag sprite-isprt-web-hk'></div><span class='name'>繁体中文 <span>- 繁體中文</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//fr' class='lang-fr'><div class='item'><div class='flag sprite-isprt-web-fr'></div><span class='name'>法国人 <span>- Francais</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//pl' class='lang-pl'><div class='item'><div class='flag sprite-isprt-web-pl'></div><span class='name'>Polish <span>- Polski</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//de' class='lang-de'><div class='item'><div class='flag sprite-isprt-web-de'></div><span class='name'>German <span>- Deutsch</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//pt' class='lang-pt'><div class='item'><div class='flag sprite-isprt-web-br'></div><span class='name'>Portuguese <span>- Português</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//vn' class='lang-vi'><div class='item'><div class='flag sprite-isprt-web-vn'></div><span class='name'>Vietnamese <span>- Tiếng Việt</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//it' class='lang-it'><div class='item'><div class='flag sprite-isprt-web-it'>🇮🇹</div><span class='name'>Italian <span>- Italiano</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//id' class='lang-id'><div class='item'><div class='flag sprite-isprt-web-id'>🇮🇩</div><span class='name'>Indonesian <span>- bahasa Indonesia</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//nl' class='lang-nl'><div class='item'><div class='flag sprite-isprt-web-nl'>🇳🇱</div><span class='name'>Dutch <span>- Nederlands</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//fa' class='lang-fa'><div class='item'><div class='flag sprite-isprt-web-ir'>🇮🇷</div><span class='name'>Persian <span>- فارسی</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//th' class='lang-th'><div class='item'><div class='flag sprite-isprt-web-th'>🇹🇭</div><span class='name'>Thai <span>- ภาษาไทย</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//hu' class='lang-hu'><div class='item'><div class='flag sprite-isprt-web-hu'>🇭🇺</div><span class='name'>Hungarian <span>- Magyar</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//el' class='lang-el'><div class='item'><div class='flag sprite-isprt-web-gr'>🇬🇷</div><span class='name'>Greek <span>- Ελληνικά</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//ro' class='lang-ro'><div class='item'><div class='flag sprite-isprt-web-ro'>🇷🇴</div><span class='name'>Romanian <span>- Română</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//bg' class='lang-bg'><div class='item'><div class='flag sprite-isprt-web-bg'>🇧🇬</div><span class='name'>Bulgarian <span>- български</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//ur' class='lang-ur'><div class='item'><div class='flag sprite-isprt-web-pk'>🇵🇰</div><span class='name'>Urdu <span>- اردو</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//hi' class='lang-hi'><div class='item'><div class='flag sprite-isprt-web-in'>🇮🇳</div><span class='name'>Hindi <span>- हिंदी</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//ar' class='lang-ar'><div class='item'><div class='flag sprite-isprt-web-ae'>🇦🇪</div><span class='name'>Arabic <span>- العربية</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//sr' class='lang-sr'><div class='item'><div class='flag sprite-isprt-web-rs'>🇷🇸</div><span class='name'>Serbian <span>- Српски</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//bn' class='lang-bn'><div class='item'><div class='flag sprite-isprt-web-bd'>🇧🇩</div><span class='name'>Bangla <span>- বাংলা</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//bs' class='lang-bs'><div class='item'><div class='flag sprite-isprt-web-ba'>🇧🇦</div><span class='name'>Bosnian <span>- босански</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//hr' class='lang-hr'><div class='item'><div class='flag sprite-isprt-web-hr'>🇭🇷</div><span class='name'>Croatian <span>- hrvatski</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//tr' class='lang-tr'><div class='item'><div class='flag sprite-isprt-web-tr'>🇹🇷</div><span class='name'>Turkish <span>- Türkçe</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//uk' class='lang-uk'><div class='item'><div class='flag sprite-isprt-web-ua'>🇺🇦</div><span class='name'>Ukrainian <span>- українська</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//cs' class='lang-cs'><div class='item'><div class='flag sprite-isprt-web-cz'>🇨🇿</div><span class='name'>Czech <span>- čeština</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//be' class='lang-be'><div class='item'><div class='flag sprite-isprt-web-by'>🇧🇾</div><span class='name'>Belarusian <span>- беларускі</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//km' class='lang-km'><div class='item'><div class='flag sprite-isprt-web-kh'>🇰🇭</div><span class='name'>Khmer <span>- ខ្មែរ</span></span></div></a><a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings//lo' class='lang-lo'><div class='item'><div class='flag sprite-isprt-web-la'>🇱🇦</div><span class='name'>Lao <span>- ລາວ</span></span></div></a></div></div></div><div class="hdrshare"><script type="text/javascript"> function initSharing(){aqisrv.here().then(function(where){country = where.Country.IsoCode;if (country!='CN') {loadScriptAsync("https://connect.facebook.net/en_US/sdk.js#xfbml=1&version=v5.0&appId=643196515742584&autoLogAppEvents=1")}}).catch(function(e){console.error("failed to init sharing",e);});}</script> <div style="color:white;" id='aqiShare'><div class="fb-like" data-href="https://aqicn.org/here/" data-width="" data-layout="button_count" data-action="like" data-size="small" data-lazy="true" data-colorscheme="dark" data-share="true"></div></div></div><div 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11.745 18.277 26.23 18.277 c 14.485 0 26.23 -8.188 26.23 -18.277 c 0.045 -0.66 0.045 -1.32 0 -1.98 C 73.635 49.855 75.056 47.528 75.011 45 z M 30.011 49.508 c 0 -2.483 2.025 -4.508 4.508 -4.508 c 2.483 0 4.508 2.025 4.508 4.508 s -2.025 4.508 -4.508 4.508 C 32.025 53.993 30.011 51.991 30.011 49.508 z M 56.152 62.058 v -0.179 c -3.199 2.405 -7.114 3.635 -11.119 3.468 c -4.005 0.168 -7.919 -1.063 -11.119 -3.468 c -0.425 -0.515 -0.347 -1.286 0.168 -1.711 c 0.447 -0.369 1.085 -0.369 1.544 0 c 2.707 1.98 6.007 2.987 9.362 2.83 c 3.356 0.179 6.667 -0.783 9.407 -2.74 c 0.492 -0.481 1.297 -0.47 1.779 0.022 C 56.655 60.772 56.644 61.577 56.152 62.058 z M 55.537 54.34 c -0.078 0 -0.145 0 -0.224 0 l 0.034 -0.168 c -2.483 0 -4.508 -2.025 -4.508 -4.508 s 2.025 -4.508 4.508 -4.508 s 4.508 2.025 4.508 4.508 C 59.955 52.148 58.02 54.239 55.537 54.34 z" style="stroke: none; stroke-width: 1; stroke-dasharray: none; stroke-linecap: butt; stroke-linejoin: miter; stroke-miterlimit: 10; fill: #25a1de; 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#adadad;text-decoration: none;color: black;}.ui-share-btn:hover svg {fill: black;}.ui-share-btn:hover svg g {fill: black;}.ui-share-btn a:hover {text-decoration: none;}</style><i style='color:#888;font-size:13px;word-break: break-all;'>分享: <a href='https://aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings/cn/'>aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings/cn/</a></i><br><div class='entry-content' ng-controller='MainController as ctrl'> <center> <div style='border:1px solid black;margin:20px;padding:10px;text-align:Center;font-size:18px;width:76%; font-size:20px; box-shadow: 0px 0px 8px rgba(0,0,0,.20);background: #fff47b;'> Please note that this article was orginally written in June 2013. <br> In April 2014, the Singapore NEA has updated the <a href='http://www.nea.gov.sg/anti-pollution-radiation-protection/air-pollution-control/psi'> PSI calculation</a> to also include PM<sub>2.5</sub>. <small> <a href='http://www.nea.gov.sg/anti-pollution-radiation-protection/air-pollution-control/psi'> http://www.nea.gov.sg/anti-pollution-radiation-protection/air-pollution-control/psi</a></small> </div> </center> <br> <p> With the recent <a href='http://www.reuters.com/article/2013/06/25/southeastasia-haze-idUSL3N0F043720130625'>Southeast Asia Smog from Indonesia</a> affecting Singapore and now <a href='http://www.bbc.co.uk/news/world-asia-23018947' target=_>Malaysia</a>, we got many questions about why there is a difference between the data which can be read from Singapore NEA website (<a href='http://nea.gov.sg/' target=_>nea.gov.sg</a>) and the World Air Quality Index project <a href='/city/singapore/central/cn/'>Singapore webpage</a>. </p> <p>例如，今天可以在 NEA 网站上看到以下内容：</p> <center> <img src='/images/nea.sg.png' width=600 style='max-width:100%'> </center> <br> <p>由于某些历史原因，新加坡使用<b>PSI</b> （<i>污染物标准指数</i>）来评估空气质量。在上图中，数字 1 对应于用于 PSI 评估的 PM10 值。值<code>67(/59)</code>可读取为 67 µg/m3，对应于 PSI 59。PSI 被评估为每种污染物的单个 PSI 的最大值：PM <sub>10</sub> 、SO <sub>2</sub> 、NO <sub>2</sub> 、O <sub>3</sub> （臭氧）和CO <sub>2</sub> 。</p> <center> <code> PSI(Singapore-North) = max( PSI<sub>PM10-based</sub>, ... PSI<sub>O3-based</sub> )= max (59, ..., 77) = 77 </code> </center> <p>尽管如此，有趣的是，在同一个表中，最后一列还提供了 PM2.5 数据（参见图 3）。该数据仅以 μg/m3 为单位提供（参见 2），并且没有转换为 PSI 之类的数据（即从 PM2.5 质量转换为污染或质量指数）。然而，这种转换是存在的，并且是由<a href='http://www.epa.gov/' target=_>美国环境保护局</a>定义的。进行转换的最简单方法是使用在线计算器，可在<a href='http://airnow.gov/index.cfm?action=resources.conc_aqi_calc' target=_>airnow.gov</a>上找到：</p> <center> <a href='/calculator/'> <img src='/images/epa.calculator.png' width=500 style='max-width:100%'> </a> </center> <br> If you select the PM2.5 (1), then enter the mass concentration of 48 (2), can click on Calculate, you will obtain the AQI of 132 (3). So, based on the PM2.5 AQI conversion, the PSI that is used for Singapore could be extended (let's call it PSI++) to also take into account the PM2.5 information. In which case, the PSI++ would be the maximum of the regular PSI (based on PM10 only) and the PM2.5 AQI: <br> <br> <center> <code> PSI++ = max( PSI, AQI<sub>PM.25</sub> ) = max( 77, 132 ) = 132 </code> </center> <br> This PSI++, that is commonly referred as AQI (or Air Quality Index), is what is being used on the the World Air Quality Index project, for all the cities (provided PM2.5 is available for the city). And this explains why the values are different between the NEA website and the World Air Quality Index project. <br><br> <center> <div style='border:1px solid black;margin:20px;padding:10px;text-align:Center;font-size:18px;width:80%; font-size:20px; box-shadow: 0px 0px 8px rgba(0,0,0,.20);background:#fff47b;text-align:left;'> Note: With the PSI update from April 2014, the only remaining difference is that the World Air Quality Index project is using a 1-hour PM<sub>2.5</sub> reading (following the <a href='/faq/2015-03-15/air-quality-nowcast-a-beginners-guide/cn/'>instantcast</a>) while Singpore PSI is based on the 3 hours average. <br> <br> Moreover, when doing the convertion, make sure you use the 1-hour reading for the PM2.5 concentration rather than the 24-hours averaged value, as shown on the below image: <br> <br> <center> <img src='/images/neasg/nea-pm25-1vs24hours-average.png' style='box-shadow: 0px 0px 8px rgba(0,0,0,.20);max-width: 100%;'> <br> <small> <a href='http://www.haze.gov.sg/haze-updates/pollutant-concentrations/type/PM25-1Hr'> http://www.haze.gov.sg/haze-updates/pollutant-concentrations/type/PM25-1Hr</a> </small> </div> </center> <br> <br> If you want to know more about PM10 vs PM2.5, and especially why PM10 is still used, please check the faq entry about <a href='/faq/2013-02-02/why-is-pm25-often-higher-than-pm10/'>why is PM2.5 often higher than PM10? Is PM10 still a relevant measure?</a> <br> <br> <link rel='stylesheet' href='/images-static/flags.css/css/flag-icon.min.css' /> <center><br>-<svg xmlns="http://www.w3.org/2000/svg" width="28" height="28" version="1" viewBox="0 0 26 26" enable-background="new 0 0 26 26"><path d="M 15.65625 -0.03125 C 14.280846 -0.03760636 12.828752 0.09254274 11.3125 0.40625 C 8.28651 1.0323169 5.7746616 2.1709106 3.96875 3.59375 C 2.3885774 4.8387345 1.3097647 6.3321654 1.0625 7.96875 A 1.0001 1.0001 0 0 0 1 8.40625 C 1 8.4709766 0.99753847 8.5296394 1 8.59375 C 0.99939321 8.6245955 1 8.6565744 1 8.6875 C 1.0067678 8.8049913 1.0164368 8.9159604 1.03125 9.03125 C 1.0536237 9.2185949 1.1014372 9.4156735 1.15625 9.59375 C 1.4590854 10.826485 2.2046296 11.91918 3.21875 12.78125 C 4.0779092 13.511593 5.1369309 14.083861 6.3125 14.53125 A 1.0001 1.0001 0 0 0 6.53125 14.9375 C 8.1339345 16.910035 12.101162 19.118434 18.1875 18.59375 A 1.0043849 1.0043849 0 0 0 18 16.59375 C 14.906411 16.860439 12.500325 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3.1893221 9.3858538 3.09375 9.1875 C 3.0413411 8.9743851 3.0082478 8.7545393 3 8.53125 C 3.0633474 7.4789308 3.7648202 6.2771492 5.1875 5.15625 C 6.6815884 3.9790894 8.91349 2.9489331 11.6875 2.375 C 13.071248 2.0887073 14.428529 1.9626064 15.65625 1.96875 z M 15.96875 3.65625 C 14.93792 3.617106 13.843984 3.69192 12.71875 3.90625 A 1.0001 1.0001 0 0 0 12.6875 3.9375 C 9.8940815 4.582135 7.6159262 5.8506824 6.5625 7.5625 A 1.0001 1.0001 0 1 0 8.25 8.625 C 8.7942179 7.740646 10.701734 6.434394 13.09375 5.875 C 13.10453 5.87295 13.11421 5.87702 13.125 5.875 C 15.064267 5.5112859 17.031887 5.6468794 18.03125 6.03125 A 1.0040202 1.0040202 0 0 0 18.75 4.15625 C 17.952461 3.8495042 16.99958 3.6953943 15.96875 3.65625 z M 9.15625 17.59375 A 1.0001 1.0001 0 0 0 8.5625 19.25 C 8.5625 19.25 11.033033 22.015963 15.53125 21.90625 A 1.0004882 1.0004882 0 1 0 15.46875 19.90625 C 11.766967 19.996537 10.0625 17.9375 10.0625 17.9375 A 1.0001 1.0001 0 0 0 9.15625 17.59375 z M 8.125 20.1875 A 1.0001 1.0001 0 0 0 7.40625 21.65625 C 7.40625 21.65625 8.6869767 23.974979 11.65625 24.09375 A 1.001098 1.001098 0 0 0 11.75 22.09375 C 9.7192733 22.012521 9.1875 20.75 9.1875 20.75 A 1.0001 1.0001 0 0 0 8.21875 20.1875 A 1.0001 1.0001 0 0 0 8.125 20.1875 z M 7.59375 23.0625 A 1.0001 1.0001 0 0 0 7.4375 23.09375 A 1.0001 1.0001 0 0 0 6.9375 23.34375 C 6.9375 23.34375 6.19375 24 5.09375 24 A 1.0001 1.0001 0 1 0 5.09375 26 C 6.99375 26 8.28125 24.84375 8.28125 24.84375 A 1.0001 1.0001 0 0 0 7.59375 23.0625 z" color="#000" ></path></svg>-<br><br></center> <div style='color:#444;background-color:#eee;padding:10px;margin:10px;border:1px dashed black;'> <b>Note</b>: <span>This article is part of a series on Worldwide Air Quality scales. </span> <br> <br> <span>For more information about specific countries or continent, please refer to those articles:</span> <a href='/faq/2015-05-02/south-asian-air-quality-scales-malaysia-and-thailand/cn/'> <div class='flag flag-icon-background flag-icon-th' style='width:22px;height:12px;display:inline-block;'></div> <div class='flag flag-icon-background flag-icon-my' style='width:22px;height:12px;display:inline-block;'></div> <span>Thailand and Malysia</span> </a> - <a href='/faq/2015-05-15/india-national-air-quality-index/cn/'> <div class='flag flag-icon-background flag-icon-in' style='width:22px;height:12px;display:inline-block;'></div> <span>India</span> </a> - <a href='/faq/2015-03-20/a-comparison-of-worldwide-air-quality-scales-part-1/cn/'> <div class='flag flag-icon-background flag-icon-cn' style='width:22px;height:12px;display:inline-block;'></div> China </a> - <a href='/faq/2015-06-03/overview-of-hong-kongs-air-quality-health-index/cn/'> <div class='flag flag-icon-background flag-icon-hk' style='width:22px;height:12px;display:inline-block;'></div> <div class='flag flag-icon-background flag-icon-ca' style='width:22px;height:12px;display:inline-block;'></div> <span>Hong Kong / Canada (Air Quality Health Index)</span> </a> - <a href='/faq/2015-05-30/air-quality-forecast-in-south-america/cn/'> <div class='flag flag-icon-background flag-icon-br' style='width:22px;height:12px;display:inline-block;'></div> <div class='flag flag-icon-background flag-icon-co' style='width:22px;height:12px;display:inline-block;'></div> <div class='flag flag-icon-background flag-icon-ec' style='width:22px;height:12px;display:inline-block;'></div> <div class='flag flag-icon-background flag-icon-pe' style='width:22px;height:12px;display:inline-block;'></div> <div class='flag flag-icon-background flag-icon-cl' style='width:22px;height:12px;display:inline-block;'></div> <div class='flag flag-icon-background flag-icon-mx' style='width:22px;height:12px;display:inline-block;'></div> <div class='flag flag-icon-background flag-icon-ar' style='width:22px;height:12px;display:inline-block;'></div> <div class='flag flag-icon-background flag-icon-uy' style='width:22px;height:12px;display:inline-block;'></div> <div class='flag flag-icon-background flag-icon-pr' style='width:22px;height:12px;display:inline-block;'></div> <span>South America</span> </a> - <a href='/faq/2014-09-06/australian-air-quality-comparison-with-the-us-epa-aqi-scale/cn/'> <div class='flag flag-icon-background flag-icon-au' style='width:22px;height:12px;display:inline-block;'></div> <span>Australia</span> </a> - <a href='/faq/2015-07-16/air-quality-scale-in-quebec-and-montreal/cn/'> <div class='flag flag-icon-background flag-icon-ca' style='width:22px;height:12px;display:inline-block;'></div> <span>Quebec and Montreal</span> </a> - <a href='/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings/cn/'> <div class='flag flag-icon-background flag-icon-sg' style='width:22px;height:12px;display:inline-block;'></div> <span>Singapore</span> </a> - <a href='/faq/2015-09-03/air-quality-scale-in-poland/cn/'> <div class='flag flag-icon-background flag-icon-pl' style='width:22px;height:12px;display:inline-block;'></div> <span>Poland</span> </a> - <a href='/faq/2015-07-18/real-time-air-quality-monitoring-in-indonesia/cn/'> <div class='flag flag-icon-background flag-icon-id' style='width:22px;height:12px;display:inline-block;'></div> <span>Indonesia</span> </a>. <p> For information about the 24 hours averaging used or Ozone and Particulate Matter (PM<sub>2.5</sub>), please refer to those two articles: <a href='/faq/2015-05-18/ground-ozone-air-quality-index-update-with-instant-cast/cn/'>Ground Ozone Index</a> - <a href='/faq/2015-03-15/air-quality-nowcast-a-beginners-guide/cn/'>PM<sub>2.5</sub> Instant Cast</a> </p> </div> </div></div></div></div><center style='border-top: 1px solid #ccc;padding:20px 0;border-bottom: 1px solid #ccc;'><style>#gaia-section-banner {word-break: break-word;cursor: pointer;font-size: 18px;line-height: 1.6;font-family: "Noto Serif", Cambria, "Palatino Linotype", "Book Antiqua", "URW Palladio L", serif;text-align: center;word-break: break-all;margin: 0;padding: 0px;min-height: 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none;}</style><div id='gaia-section-banner'><div><div style='display:block'><span>您知道您所在地区的任何空气质量站吗？</span> <span>为什么不将自己的空气质量站纳入地图呢？</span></div><img src='/air/view/gaia/images/gaia-series-a12-icon-with-map.png'><a href='/gaia/list/cn/' target=gaia_a08><span>了解更多信息</span><div> > aqicn.org/gaia/ <</div></a></div></div><script>try {aqisrv.here().then(function(where) {var country = where.Country.IsoCode;var o = document.getElementById('gaia-section-banner');if (1 || country == 'FR' || country == 'ES') {o.style.display = '';o.style.visibility = 'visible';o.onclick = function() {window.location.assign('/gaia/list/cn/');}}}).catch(function(e) {});} catch (e) {}</script></center><center style='background-color: #ffffff;padding:20px 0;'><ins class="adsbygoogle" style="display:block" data-ad-client="ca-pub-0281575029452656" data-ad-slot="2455076269" data-ad-format="auto"></ins><script>(adsbygoogle = window.adsbygoogle || []).push({});</script></center><center style='padding:10px 0;border-top: 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#ccc;background:white;padding-bottom:20px;'><div class='section-content'><a href='/faq/cn/'><h2><span>单击此处查看所有常见问题解答条目</span></h2></a><div style='margin-left: 20px;line-heigh:1.5;color:#888;' class='faqmore'><style type='text/css'>.faqmore li a:hover {background: #62a6c8;color: white;text-decoration: none;}.faqmore li a {color: #000;}</style><li><a href='https://aqicn.org/scale/cn/'>AQI Scale: What do the colors and numbers mean?</a></li><li><a href='https://aqicn.org/faq/using-statistical-distances-for-real-time-sensor-networks-validation/cn/'>Using Statistical Distances for Real-time Sensor Networks Validation</a></li><li><a href='https://aqicn.org/faq/2017-01-10/nitrogen-dioxyde-no2-in-our-atmosphere/cn/'>Nitrogen Dioxyde (NO<sub>2</sub>) in our atmosphere</a></li><li><a href='https://aqicn.org/faq/2016-08-10/ozone-aqi-scale-update/cn/'>Ozone AQI Scale update</a></li><li><a href='https://aqicn.org/faq/2016-02-28/air-quality-forecasting-in-northern-india/cn/'>Air Quality Forecasting in Northern India</a></li><li><a href='https://aqicn.org/faq/2015-11-05/a-visual-study-of-wind-impact-on-pm25-concentration/cn/'>A visual study of Wind impact on PM<sub>2.5</sub> Concentration</a></li><li><a href='https://aqicn.org/faq/2015-10-28/unep-air-quality-monitoring-station/cn/'>UNEP Air Quality Monitoring Station</a></li><li><a href='https://aqicn.org/faq/2015-09-21/health-effects-of-respiratory-exposure-to-sulphur-dioxide-/cn/'>Health effects of respiratory exposure to sulphur dioxide </a></li><li><a href='https://aqicn.org/faq/2015-09-20/asean-air-quality-tile-map-service/cn/'>Asean Air Quality Tile Map Service</a></li></div></div></center><a name="infoaqi"></a><div class='h1section h1section-divider'><div class='h1section-rainbow'><div></div><div></div><div></div><div></div><div></div></div><h1><div id='h1header3' style='padding:2px;font-family:"Noto Serif",Cambria,"Palatino Linotype","Book Antiqua","URW Palladio L",serif;;'>关于空气质量与空气污染指数</div></h1></div><script type='text/javascript'> ; if (!isMobileUA) { fitLine('#h1header3',.88,{maxfs:45}); }; </script><div class='whitebody' style='font-family:"Noto Serif",Cambria,"Palatino Linotype","Book Antiqua","URW Palladio L",serif;'><div class='section-outer'><div class='section-content' ><center>本网站采用的污染指数和颜色与EPA是完全相同的。 EPA的指数可以从<a href='http://zh.wikipedia.org/wiki/%E7%A9%BA%E6%B0%94%E8%B4%A8%E9%87%8F%E6%8C%87%E6%95%B0>维基百科</a>和<a href='http://www.airnow.gov/index.cfm?action=aqibasics.aqi'> AirNow</a>上查到<br><br><style type="text/css">#legend-full table.infoaqitable {line-height: 1.5;background-color: white;max-width: 1000px;width: 95%;margin: 0px;border: 1px solid black;cursor: pointer;}#legend-full table.infoaqitable td {padding: 5px;font-size: 15px;text-shadow: none;}#legend-full .aqiwtxt {color: #ffffff;}#legend-full .aqibtxt {color: #000000;}@media only screen and (max-width: 800px) {#legend-full table.infoaqitable {width: 98%;}}@media only screen and (max-width: 800px) {#legend-full table.infoaqitable td {display: block;}#legend-full table.infoaqitable td:nth-child(1) {display: inline-block;font-size: 1.2em;}#legend-full table.infoaqitable td:nth-child(2) {display: inline-block;font-weight: 800;font-size: 1.2em;}}</style><div id='legend-full' onclick='window.location="/scale/"'><table class="infoaqitable"><tbody><tr><td style="text-align:center;">空气质量指数</td><td style="text-align:center;">空气质量指数级别（状况）及表示颜色</td><td>对健康影响情况</td><td>建议采取的措施</td></tr><tr style="background-color:#009966;color:white"><td nowrap="true">0 - 50</td><td style="text-align:center;">一级（优）</td><td>空气质量令人满意，基本无空气污染</td><td>各类人群可正常活动</td></tr><tr style="background-color:#ffde33"><td nowrap="true">51 -100</td><td style="text-align:center;">二级（良）</td><td>空气质量可接受，但某些污染物可能对极少数异常敏感人群健康有较弱影响</td><td>极少数异常敏感人群应减少户外活动</td></tr><tr style="background-color:#ff9933;color:white"><td nowrap="true">101-150</td><td style="text-align:center;">三级（轻度污染）</td><td>易感人群症状有轻度加剧，健康人群出现刺激症状</td><td>儿童、老年人及心脏病、呼吸系统疾病患者应减少长时间、高强度的户外锻炼</td></tr><tr style="background-color:#cc0033;color:white"><td nowrap="true">151-200</td><td style="text-align:center;color:white">四级（中度污染）</td><td>进一步加剧易感人群症状，可能对健康人群心脏、呼吸系统有影响</td><td>儿童、老年人及心脏病、呼吸系统疾病患者避免长时间、高强度的户外锻炼，一般人群适量减少户外运动</td></tr><tr style="background-color:#660099;color:white"><td nowrap="true">201-300</td><td style="text-align:center;color:white">五级（重度污染）</td><td>心脏病和肺病患者症状显著加剧，运动耐受力降低，健康人群普遍出现症状</td><td>儿童、老年人及心脏病、肺病患者应停留在室内，停止户外运动，一般人群减少户外运动</td></tr><tr style="background-color:#7e0023;color:white"><td nowrap="true">300+</td><td style="text-align:center;color:white">六级（严重污染）</td><td>健康人群运动耐受力降低，有明显强烈症状，提前出现某些疾病</td><td>儿童、老年人和病人应停留在室内，避免体力消耗，一般人群避免户外活动</td></tr></tbody></table>(参考详见<a href='http://zh.wikipedia.org/wiki/%E7%A9%BA%E6%B0%94%E8%B4%A8%E9%87%8F%E6%8C%87%E6%95%B0'>http://zh.wikipedia.org/wiki/空气质量指数</a>)<br></div><br>如果你想了解更多有关空气质量与污染，详见<a href='http://en.wikipedia.org/wiki/Air_quality'>维基百科</a>或者<a href='http://www.airnow.gov/index.cfm?action=aqibasics.aqi'> AirNow</a><br><br>有关健康建议详见北京的Richard Saint Cyr MD医生的博客：<a href='http://www.myhealthbeijing.com/'>www.myhealthbeijing.com</a><br><br></center></div></div></div><center><br><ins class="adsbygoogle" style="display:block"data-ad-client="ca-pub-0281575029452656"data-ad-slot="2455076269"data-ad-format="auto"></ins><script>(adsbygoogle = window.adsbygoogle || []).push({});</script><style type='text/css'>.usage-notice {line-height:1.5;max-width:95%;width:1000px;margin-top:10px;padding:5px;font-size: 15px;background-color:#ffffff;text-shadow: 1px 1px 1px white;-webkit-box-shadow: 1px 1px 8px -3px rgba(0,0,0,0.3);}</style><div class="textshadowwhite usage-notice" style=''><b>注意事项</b>: 所有空气质量数据在发布时均未经验证，并且为了保证数据质量，这些数据可能随时被修改，恕不另行通知。 <a href='https://aqicn.org'>世界空气质量指数</a>项目在编制此信息的内容时已经运用了所有合理的技能和谨慎，在任何情况下<a href 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