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Check out the real-time air pollution map, for more than 100 countries."><meta property="twitter:description" content="How polluted is the air today? Check out the real-time air pollution map, for more than 100 countries." /><meta property="og:title" content="A Beginner\'s Guide to Air Quality Instant-Cast and Now-Cast. " /><meta property="twitter:title" content="A Beginner\'s Guide to Air Quality Instant-Cast and Now-Cast. 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href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//ro'><div title='Romanian' class='sprite-isprt-web-ro flag-ro'>🇷🇴</div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//bg'><div title='Bulgarian' class='sprite-isprt-web-bg flag-bg'>🇧🇬</div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//ur'><div title='Urdu' class='sprite-isprt-web-pk flag-ur'>🇵🇰</div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//hi'><div title='Hindi' class='sprite-isprt-web-in flag-hi'>🇮🇳</div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//ar'><div title='Arabic' class='sprite-isprt-web-ae flag-ar'>🇦🇪</div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//sr'><div title='Serbian' class='sprite-isprt-web-rs flag-sr'>🇷🇸</div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//bn'><div title='Bangla' class='sprite-isprt-web-bd flag-bn'>🇧🇩</div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//bs'><div title='Bosnian' class='sprite-isprt-web-ba flag-bs'>🇧🇦</div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//hr'><div title='Croatian' class='sprite-isprt-web-hr flag-hr'>🇭🇷</div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//tr'><div title='Turkish' class='sprite-isprt-web-tr flag-tr'>🇹🇷</div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//uk'><div title='Ukrainian' class='sprite-isprt-web-ua flag-uk'>🇺🇦</div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//cs'><div title='Czech' class='sprite-isprt-web-cz flag-cs'>🇨🇿</div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//be'><div title='Belarusian' class='sprite-isprt-web-by flag-be'>🇧🇾</div></a></div><div id='hdrlang-navigation'><div id='hdrlang-navigation-inner' class='hdrlang-navigation'><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide/' class='lang-en'><div class='item'><div class='flag sprite-isprt-web-gb'></div><span class='name'>English</span></div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//cn' class='lang-zh-CN'><div class='item'><div class='flag sprite-isprt-web-cn'></div><span class='name'>Chinese <span>- 简体中文</span></span></div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//jp' class='lang-ja'><div class='item'><div class='flag sprite-isprt-web-jp'></div><span class='name'>Japanese <span>- 日本</span></span></div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//es' class='lang-es'><div class='item'><div class='flag sprite-isprt-web-es'></div><span class='name'>Spanish <span>- español</span></span></div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//kr' class='lang-ko'><div class='item'><div class='flag sprite-isprt-web-kr'></div><span class='name'>Korean <span>- 한국의</span></span></div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//ru' class='lang-ru'><div class='item'><div class='flag sprite-isprt-web-ru'></div><span class='name'>Russian <span>- русский</span></span></div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//hk' class='lang-zh-TW'><div class='item'><div class='flag sprite-isprt-web-hk'></div><span class='name'>Traditional Chinese <span>- 繁體中文</span></span></div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//fr' class='lang-fr'><div class='item'><div class='flag sprite-isprt-web-fr'></div><span class='name'>French <span>- Francais</span></span></div></a><a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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/2015-03-15/air-quality-nowcast-a-beginners-guide//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></div></div></div><div class="hdrshare"><script type="text/javascript"> function initSharing(){aqisrv.here().then(function(where){country = where.Country.IsoCode;if (country!='CN') 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0.3em;border-radius: 0.3em;color: black;font-family: Consolas, Monaco, 'Andale Mono', monospace;direction: ltr;text-align: left;white-space: pre;overflow: scroll;word-wrap: break-word;word-spacing: normal;color:#c92c2c;}code.code-snippet-inline span.string {color: #2f9c0a;}code.code-example {font-family: Consolas, Monaco, 'Andale Mono', monospace;background-color:#f8f8f8;border:1px solid #888;padding:20px;display:inline-block;margin:20px;font-size:15px;line-height:1.2;text-align:left;-webkit-box-shadow: 0px 0px 0px 1px #dfdfdf;-moz-box-shadow: 0px 0px 0px 1px #dfdfdf;box-shadow: 0px 0px 0px 1px #dfdfdf;background-color: #fdfdfd;-webkit-border-radius: 0.3em;-moz-border-radius: 0.3em;-ms-border-radius: 0.3em;-o-border-radius: 0.3em;border-radius: 0.3em;}</style><div class='h1section'><h1><div id='h1header1' style='padding:2px;padding:5px 0;font-family:"Noto Serif",Cambria,"Palatino Linotype","Book Antiqua","URW Palladio L",serif;;;'>A Beginner's Guide to Air Quality Instant-Cast and Now-Cast. </div></h1></div><script type='text/javascript'> ; if (!isMobileUA) { fitLine('#h1header1',.88,{maxfs:45}); }; </script><style>.section-outer {text-align: initial;}.section-content {max-width: 95%;width: 1100px;font-size: 18px;min-height: 300px;text-align: initial;margin-top: 10px;margin-bottom: 10px;line-height: 1.8;margin-left: auto;margin-right: auto;}.section-content-tight {min-height: 0px;}.section-content-alt {background-color: #f0f0f0;border-top: 1px solid #ccc;border-bottom: 1px solid #ddd};.section-banner {background-size: 100%;background: url(https://aqicn.org/images//bluesky-banner-panoramic.jpg) no-repeat center bottom #eee;margin-top: -2px;z-index: -1;border-bottom: 1px solid #888;width: 100%;}.h2-title {font-family: inherit;font-size: 1.1em;overflow: hidden;text-align: center;text-transform: capitalize;}.h2-title:before,.h2-title:after {background-color: #ddd;content: '';display: inline-block;height: 1px;position: relative;vertical-align: middle;width: 50%;}.h2-title:before {right: 0.5em;margin-left: -50%;}.h2-title:after {left: 0.5em;margin-right: -50%;}@media only screen and (max-width: 800px) {.section-content {line-height: 1.6;max-width: 98%;min-height: 10px;}.section-banner {display: none;}}</style><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' ><i>Posted on March 15<sup>th</sup> 2015</i><div style='height:1px;background-color:#aaaaaa;width:300px;margin-top:5px;'></div><small><i>(re-edited on January 12<sup>th</sup> 2020)</i></small><br><div id="gtrans-div-id" style="float:right" class="gtrans-div"></div><script>try { googleTranslate(); } catch (e) {}</script><div class='ui-share-btns'><a id='share-facebook' 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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;'>Share: <a href='https://aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide/'>aqicn.org/faq/2015-03-15/air-quality-nowcast-a-beginners-guide/</a></i><br><div class='entry-content' ng-controller='MainController as ctrl'> <div style='float:right;padding-left:10px;'> <img src='/images/nowcast/typhoon-asia-2004293.jpg' width=468> <center> <small> Typhoon and Dust on East Asia, Courtesy of NASA (<a href='http://alliance.la.asu.edu/mywonderfulworld/GeoLiteracy/WilliamsNature/williamsnature.html'>attribution</a>) </small> </center> <script> if (0) cityShowAd("6885275862", 300, 100); </script> <br> </div> <p> Back in March 2015, we had the chance to meet in Beijing several environmental specialists from the US State Department as well as the China Mission (<i>the famous entity running the PM<sub>2.5</sub> monitors in the Beijing US embassy</i>). </p> <p> Among all the topics that were addressed, there is one worth writing about, namely the "<i><b>nowcast</b></i>" system. This system used by the US EPA to convert the raw pollutants readings, expressed in µg/m3 or<i> ppb</i>, into the AQI (scale from 0 to 500). It is used for all the AQI values reported on the <a href='http://airnow.gov'>airnow.gov</a> website. </p> <p> The concept behind the <i>nowcast</i> is to compensate the "<i>24 hours averaging</i>", which should be used when converting concentrations to AQI. The reason for this averaging is that the <a href='http://airnow.gov/index.cfm?action=aqibasics.aqi'>AQI scale</a> specifies that each of the Levels of Health Concern (i.e. Good, Moderate,... Unhealthy...) is valid under a 24 hours exposure<sup><a href="#nowcast-footnote-1">[1]</a></sup>. For example, when seeing a 188 AQI (Unhealthy), one need to read it as "<i style='color:#888;'>if I stay out for 24 hours, and the AQI is 188 <span style='color:#cc0033;'>during those 24 hours</span>, then the health effect is Unhealthy</i>". This is quite different from saying that "<i style='color:#888;'>if the AQI reported now is 188, then the health effect is Unhealthy</i>". </p> <p> The problem is that the 24 hours averaging is a <b>very bad idea</b>, and should abolished<sup><a href="#nowcast-footnote-3">[3]</a></sup> for at least those two reasons: </p> <ul> <li> First, the dynamic of Air Pollution is such that wind than completely clean the air in less than 30 minutes! This phenomenon is frequently seen in Beijing with the strong north winds able to bring the PM<sub>2.5</sub> AQI from more than 300 to less than 50 in less than one hour<sup><a href="#nowcast-footnote-2">[2]</a></sup>. When this happens, no one wants to wait for 24 hours before knowing that the Air Quality is good (and go out for a walk to enjoy the fresh air!) <br> <br> <li> The second reason is when the Air Quality suddenly gets worse. One famous case is the Indonesian wildfire causing the Singapore Smog when the winds are heading to the north, under which circumstances the AQI can go from below 50 to more than 150 is just one hour. As a matter of fact, we have had many requests from asthmatic/sensitive people when Singapore was still only providing 24 hours average readings. </ul> <p> This is for those reasons that the US EPA introduced the <i>nowcast</i> system: It is an alternative conversion formula used to counter balance the need for averaging under changing Air Quality conditions. From <a href='http://en.wikipedia.org/wiki/Nowcast_%28Air_Quality_Index%29'>Wikipedia</a>, it is described as: </p> <blockquote> The NowCast is computed from the most recent 12 hours of PM monitoring data, but the NowCast weights the most recent hours of data more heavily than an ordinary 12-hour average when pollutant levels are changing. The NowCast is used in lieu of a 24-hour average PM concentration in the calculation of the AQI until an entire calendar day of hourly concentrations has been monitored." </blockquote> <p> The formula used to calculate the <i>NowCast</i> AQI might seem barbarian for non-scientist. </p> <center style='font-family:"Times New Roman",serif'> <img src='/images/nowcast/nowcast-formula-generalized.png' width=600 style='vertical-align: middle;'> <span style='color:#888'>and </span> <i style='color:#1166c7'>W<sub>min</sub></i> = <sup>1</sup>/<sub>2</sub> <span style='color:#888'>and </span> <i style='color:#1166c7'>N</i> = 12 </center> <br> <p> But actually, it is quite simple when looking at this applied example for Beijing Air Quality. </p> <style type="text/css"> .axis path, .axis line { fill: none; font-size: 12px; stroke: black; shape-rendering: crispEdges; } .nowcastgraphs { font-size: 15px; border: 1px solid #cccccc; background-color: #f8f8f8; display: inline-block; width: 100%; padding: 10px; text-align: left; color: #888888; margin: 0 0 5px 0; box-sizing: border-box; } </style> <center> <span class='nowcastgraphs'> Instant AQI (no averaging, AQI converted directly from the 1 hour readings): <div id='instantAQI' style='font-size:12px;halign:center;'></div> <br> NowCast AQI: <div id='nowcastAQI' style='font-size:12px;halign:center;'></div> <br> </span> </center> <p> The result from the <i>nowcast</i> calculated AQI is still very pronounced in terms of averaging, at least much more than what one living in the Asian dust would expect. One of the reasons is that the weight factor, which used to determine the level of change, has a threshold set to a minimum of 0.5, while in actual fact, its value is much lower than 0.5 is many cases. The following graph shows this threshold weight factor, where red is used to denote those weigths below 0.5 </p> <center> <span class='nowcastgraphs'> NowCast weight factors: <div id='weightfactor' style='font-size:12px;halign:center;'></div> </span> </center> <p> The nowcast formula, as it is defined nowdays, is the fruit of the research based on Air Quality levels in America. While for USA it gives an accurate reporting of the current conditions, it might not be the case of Asia where the dynamic of Air Quality is much more strong. For this reason, we do believe that the <i>nowcast</i> formula should be adapted for each continents. </p> For Asia, it could be defined as <span style='font-family:"Times New Roman",serif'> <i style='color:#1166c7'>W<sub>min</sub></i> = <sup>1</sup>/<sub>10</sub> <span style='color:#888'>and </span> <i style='color:#1166c7'>N</i> = 3 </span>, corresponding to the following graph: <center> <span class='nowcastgraphs'> Modified NowCast for Asia (aka NowCast Asia AQI): <div id='nowcastasiaAQI' style='font-size:12px;halign:center;'></div> <center> <small> <br> If you want, you can also directly change the two parameters yourself: <span style='font-family:"Times New Roman",serif'> <i style='color:#1166c7'>W<sub>min</sub></i> = <input type='number' value=.1 class='nowcastparams' id='nowcastwmin'> <span style='color:#888'> and </span> <i style='color:#1166c7'>N</i> = <input type='number' value=3 class='nowcastparams' id='nowcastn'> </span> </small> </center> For reference, Instant AQI: <div id='instantAQI2' style='font-size:12px;halign:center;'></div> </span> </center> <style type="text/css"> .nowcastparams { padding: 3px; font-size: 18px; text-align: center; width: 50px; } </style> <p> For now, the conversion formula used on the <a href='/home/'>World Air Quality Index project</a> as well as the China Mission AQI (aka the Beijing US embassy, Shanghai US consulate, etc..) is still based on the "<b>Instant AQI</b>", a.k.a "InstantCast" (i.e. no averaging at all). But, based on the outcome of this "Asian Nowcast" proposal, this might be updated quite soon. </p> <script src='/jscripts/d3/d3.min.js?_=20190418.093123&type=script'></script><script src='/jscripts/moment/bundle.min.js?_=20200103.150752&type=script'></script><script src='/air/view/stats/plot.js?_=20190418.093129&type=script'></script><script src='/air/view/stats/nowcast-plot.js?_=20190418.093129&type=script'></script><link href='/air/view/stats/style.css?_=20190418.093129&type=css' rel='stylesheet'/> <script type='text/javascript'></script> <script type='text/javascript'> function calculatePm25Aqi(val) { var c = parseFloat(val); var range = [0, 50, 100, 150, 200, 300, 400, 500]; var scale = [0, 12, 35.5, 55.5, 150.5, 250.5, 350.5, 500.5]; for (var i = 0; i < scale.length - 1; i++) { if (c >= scale[i] && c < scale[i + 1]) { var aqi = range[i] + (c - scale[i]) * (range[i + 1] - range[i]) / (scale[i + 1] - scale[i]); aqi = Math.round(aqi); return aqi; } } return 500; } function instantAQI(val) { return calculatePm25Aqi(val / 1000); } function nowcastAQI(val, p, opt) { var minweight = opt.minweight || .5; var cmin = -1, cmax = -1; p.forEach(function(c) { if (cmin == -1 || cmin > c) cmin = c; if (cmax == -1 || cmax < c) cmax = c; }); var w = Math.max(minweight, cmin / cmax); var v = (val / 1000); var i = 1, div = 1, s = 1; p.forEach(function(c) { s *= w; v += c * s / 1000; div += s; }); v /= div; v = calculatePm25Aqi(v); return Math.round(v); } function weightfactor(val, p) { var cmin = -1, cmax = -1; p.forEach(function(c) { if (cmin == -1 || cmin > c) cmin = c; if (cmax == -1 || cmax < c) cmax = c; }); return Math.round(100 * cmin / cmax) / 100; } function weightcolor(v) { var colors = [ '#ff0000','#cc1b28','#993650','#665078','#336ba0','#0086c8','#0086c8','#339ed3','#66b6de','#99cfe9','#cce7f4','#ffffff',]; return colors[Math.round(v * 10)]; } var beijing = { "cityID": "Beijing", "pol": "pm25", "ndays": "15", "data": [1426316400, 67000, "", -11000, "", -2000, "", 5000, "", 3000, "", 5000, "", 3000, "", 22000, "", 4000, "", -55000, "", 0, "", -7000, "", -7000, "", -15000, "", 4000, "", 2000, "", -9000, "", 8000, "", 4000, "", -4000, "", 9000, "", 14000, "", 78000, "", 37000, "", -25000, "", -4000, "", -15000, "", -1000, "", 13000, "", 11000, "", 12000, "", -21000, "", -14000, "", -27000, "", 2000, "", 4000, "", -15000, "", -16000, "", -13000, "", -16000, "", 12000, "", 5000, "", 16000, "", 23000, "", -8000, "", 11000, "", -4000, "", 3000, "", 6000, "", -1000, "", -10000, "", -2000, "", -7000, "", -1000, "", 4000, "", -1000, "", -21000, "", -11000, "", -5000, "", -6000, "", -10000, "", -5000, "", -3000, "", 3000, "", -3000, "", -1000, "", -3000, "", 5000, "", -10000, "", 11000, "", 14000, "", 0, "", 54000, "", 8000, "", 8000, "", -3000, "", 6000, "", -11000, "", -18000, "", 3000, "", -6000, "", 0, "", -1000, "", -5000, "", -30000, "", -6000, "", 5000, "", 4000, "", -2000, "", -11000, "", -11000, "", 1000, "", -8000, "", 17000, "", 13000, "", -5000, "", -11000, "", -14000, "", -1000, "", -5000, "", 2000, "", 3000, "", 2000, "", -1000, "", 2000, "", -2000, "", 1000, "", -1000, "", 0, "", -3000, "", 3000, "", 3000, "", -1000, "", -2000, "", 1000, "", 1000, "", -2000, "", 7000, "", -9000, "", -4000, "", 1000, "", 1000, "", 0, "", 1000, "", 0, "", 5000, "", -3000, "", 3000, "", 7000, "", -8000, "", 5000, "", -6000, "", -1000, "", 3000, "", -1000, "", 3000, "", -1000, "", 1000, "", 0, "", 113000, "", 112000, "", 8000, "", 11000, "", -18000, "", -24000, "", -11000, "", 20000, "", 5000, "", -11000, -7200, -16000, "", 12000, "", 7000, "", 11000, "", -5000, "", -12000, "", -13000, "", -1000, "", -6000, "", -4000, "", -14000, "", 21000, "", 14000, "", 8000, "", 15000, "", -12000, "", -2000, "", 1000, "", 23000, "", -4000, "", 22000, "", 14000, "", 5000, "", -1000, "", 21000, "", 12000, "", 3000, "", -28000, "", -2000, "", -33000, "", -10000, "", -12000, "", -20000, "", -22000, "", 26000, "", 0, "", -2000, "", -10000, "", -23000, "", -9000, "", -17000, "", 1000, "", 10000, "", -1000, "", 14000, "", 3000, "", 20000, "", -57000, "", -26000, "", 24000, "", 11000, "", 9000, "", -22000, "", -47000, "", -18000, "", -2000, "", 0, "", -3000, "", -8000, "", 3000, "", 28000, "", 4000, "", 65000, "", -18000, "", -10000, "", 1000, "", -2000, "", -15000, "", -7000, "", 21000, "", -9000, "", -13000, "", -15000, "", -20000, "", -15000, "", -5000, "", -13000, "", -4000, "", -7000, "", -10000, "", 2000, "", 0, "", 8000, "", -13000, "", -6000, "", -3000, "", 6000, "", 3000, "", 2000, "", -2000, "", -8000, "", 2000, "", 1000, "", -1000, "", -1000, "", -4000, "", 1000, "", 0, "", 0, "", 3000, "", 3000, "", -2000, "", 1000, "", -1000, "", -5000, "", -1000, "", 1000, "", 1000, "", 3000, "", -5000, "", 0, "", 1000, "", 1000, "", -1000, "", -1000, "", -2000, "", -1000, "", 1000, "", 1000, "", 2000, "", -1000, "", -2000, "", 2000, "", 3000, "", 2000, "", 5000, "", -2000, "", 4000, "", 8000, "", -4000, "", -4000, "", 12000, "", 25000, "", 45000, "", 30000, "", 1000, "", 7000, "", 7000, "", -11000, "", -17000, "", -14000, "", -21000, "", -5000, "", -3000, "", 0, "", -5000, "", -11000, "", -11000, "", 4000, "", -11000, "", -15000, "", -8000, "", -4000, "", 7000, "", 7000, "", -1000, "", -4000, "", 17000, "", 14000, "", 7000, "", 8000, "", -2000, "", -35000, "", -16000, "", -3000, "", 0, "", 9000, "", 23000, "", 71000, "", -63000, "", 71000, "", 85000, "", 12000, "", 7000, "", -3000, "", -7000, "", -6000, "", 2000, "", 21000, "", -19000, "", -5000, "", -24000, "", -15000, "", -49000, "", -19000, "", -9000, "", -20000, "", -13000, "", -10000, "", -8000, "", 5000, "", -5000, "", 2000, "", 4000, "", -1000, "", -10000, "", 0, "", 4000, "", 1000, "", -2000, "", 6000, "", -9000, "", -10000, "", 3000, "", -4000, "", 4000, "", -12000, "", 0, "", 1000, "", -2000, "", -9000, "", 1000, "", -2000, "", 2000, "", 4000, "", -6000, "", 0, "", 4000, "", -1000, "", 5000, "", 2000, "", -3000, "", 0, "", -6000, "", 7000, "", -3000, "", 4000, "", -3000, "", 7000, "", -11000, "", 4000, "", 1000, "", -5000, "", 3000, "", -5000, "", 2000, "", 4000, "", 16000, "", -8000, "", -4000, "", 8000, "", -12000], "utime": "2015-03-14 07:00:00", "step": -3600 }; function initPage() { $('.nowcastparams').bind('input propertychange', function() { var wmin = $("#nowcastwmin").val(); var n = $("#nowcastn").val(); console.log(typeof parseInt(n)); if (typeof parseInt(wmin) == 'number' && typeof parseInt(n) == 'number') { $("#nowcastasiaAQI").html(""); new NowCastGraph("#nowcastasiaAQI").plot(beijing, width, height, nowcastAQI, { minweight: wmin, qlen: n }); } }); var width = document.getElementById("instantAQI").clientWidth - 20; var height = 100; new NowCastGraph("#instantAQI2").plot(beijing, width, 80, instantAQI); new NowCastGraph("#instantAQI").plot(beijing, width, height, instantAQI); new NowCastGraph("#nowcastAQI").plot(beijing, width, height, nowcastAQI, { minweight: .5 }); new NowCastGraph("#weightfactor").plot(beijing, width, 88, weightfactor, { colorf: weightcolor, minv: -.1, maxv: 1 }); new NowCastGraph("#nowcastasiaAQI").plot(beijing, width, height, nowcastAQI, { minweight: .1, qlen: 3 }); } </script> <br> <br> ... <br> <br> <div style='border-top:1px solid black;width:120px;'></div> <small> <div id='nowcast-footnote-1'> [1] The 24 hours duration is based on decades of <a href='http://en.wikipedia.org/wiki/Epidemiology'>epidemiological studies</a> used to correlate the air pollution exposure and increased risk for health. There are new ongoing epidemiological studies to correlate the effect of <b>instant exposure</b> (i.e. exposure of around 1 hour or less), but it can take several years before their results can be converted to a new offical "instant AQI scale". </div> <div id='nowcast-footnote-2'> [2] Strong wind have quite often an effect on increasing the PM<sub>10</sub> AQI due to the dust re-suspension. </div> <div id='nowcast-footnote-3'> [3] At the time of writing , in March 2015, there were many countries still providing only 24 hours average. Nowdays, in September 2016, the only two known countries still providing only 24 hours average are <a href='http://apims.doe.gov.my'>Malaysia</a> and <a href='http://www.env.gov.bn/'>Brunei</a>. All other countries are providing not only underage (hourly) data, but also individual concentration for each pollutant. </small> <br> <br> </div></div></div></div><center style='border-top: 1px solid #ccc'><center style='margin:10px 0;'><ins class="adsbygoogle" style="display:block" data-ad-client="ca-pub-0281575029452656" data-ad-slot="2455076269" data-ad-format="auto"></ins></center><script>(adsbygoogle = window.adsbygoogle || []).push({});</script><div class='section-content'><a href='/faq/" . srvLang() . "'>Click here to see all the FAQ entries</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: #888;}</style><li><a href='https://aqicn.org/scale/'>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/'>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/'>Nitrogen Dioxyde (NO<sub>2</sub>) in our atmosphere</a></li></div><div style='height:1px;background-color:#aaaaaa;width:220px;margin-top:5px;'></div><center><script>var i18nTexts=(i18nTexts||[]);i18nTexts.push([])</script><script src='/webapp/dist/mailing-dyn.740fe2cfc24722505254.js?_=1706407958' type='text/javascript'></script></center><div id='ntf-body-first' style='display:none;'></div><script>function ntfConf() {return {page: "faq",divId: "ntf-body-first"}}</script></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='h1header2' style='padding:2px;font-family:"Noto Serif",Cambria,"Palatino Linotype","Book Antiqua","URW Palladio L",serif;;'>About the Air Quality and Pollution Measurement:</div></h1></div><script type='text/javascript'> ; if (!isMobileUA) { fitLine('#h1header2',.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>About the Air Quality Levels<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 cautionary"><thead><tr><td>AQI</td><td>Air Pollution Level</td><td>Health Implications</td><td>Cautionary Statement (for PM2.5)</td></tr></thead><tr style="background-color:#009966;"><td class='aqiwtxt' nowrap="true">0 - 50</td><td class='aqiwtxt'>Good</td><td class='aqiwtxt'>Air quality is considered satisfactory, and air pollution poses little or no risk</td><td class='aqiwtxt'>None</td></tr><tr style="background-color:#ffde33" class='aqibtxt'><td class='aqibtxt' nowrap="true">51 -100</td><td class='aqibtxt'>Moderate</td><td class='aqibtxt'>Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.</td><td class='aqibtxt'>Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.</td></tr><tr style="background-color:#ff9933;"><td class='aqibtxt' nowrap="true">101-150</td><td class='aqibtxt'>Unhealthy for Sensitive Groups</td><td class='aqibtxt'>Members of sensitive groups may experience health effects. The general public is not likely to be affected.</td><td class='aqibtxt'>Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.</td></tr><tr style="background-color:#cc0033;"><td class='aqiwtxt' nowrap="true">151-200</td><td class='aqiwtxt'>Unhealthy</td><td class='aqiwtxt'>Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects</td><td class='aqiwtxt'>Active children and adults, and people with respiratory disease, such as asthma, should avoid prolonged outdoor exertion; everyone else, especially children, should limit prolonged outdoor exertion</td></tr><tr style="background-color:#660099;"><td class='aqiwtxt' nowrap="true">201-300</td><td class='aqiwtxt'>Very Unhealthy</td><td class='aqiwtxt'>Health warnings of emergency conditions. The entire population is more likely to be affected.</td><td class='aqiwtxt'>Active children and adults, and people with respiratory disease, such as asthma, should avoid all outdoor exertion; everyone else, especially children, should limit outdoor exertion.</td></tr><tr style="background-color:#7e0023;"><td class='aqiwtxt' nowrap="true">300+</td><td class='aqiwtxt'>Hazardous</td><td class='aqiwtxt'>Health alert: everyone may experience more serious health effects</td><td class='aqiwtxt'>Everyone should avoid all outdoor exertion</td></tr></table></div><br>To know more about Air Quality and Pollution, check the <a href='http://en.wikipedia.org/wiki/Air_quality'>wikipedia Air Quality topic</a> or the <a href='http://www.airnow.gov/index.cfm?action=aqibasics.aqi'>airnow guide to Air Quality and Your Health</a>.<br><br>For very useful health advices of Beijing Doctor Richard Saint Cyr MD, check <a href='http://www.myhealthbeijing.com/'>www.myhealthbeijing.com</a> blog.<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>Usage Notice</b>: All the Air Quality data are unvalidated at the time of publication, and due to quality assurance these data may be amended, without notice, at any time. 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