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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; fill-rule: nonzero; opacity: 1;" transform=" matrix(1 0 0 1 0 0) " stroke-linecap="round" /></g></svg></a><script>try{tlite.enable(document.getElementById('share-reddit'),{text:"<div style='font-size:120%'>Share on reddit:<\/div>Air Quality Gas Sensor analysis<br>(https:\/\/aqicn.org\/sensor\/gas\/)"});}catch(e){}</script></div><style>.ui-share-btns { display: block; margin: 0; vertical-align: middle; } .ui-share-btns svg { height: 20px; vertical-align: middle; fill: white; } .ui-share-btn { background-color: #25a1de; color: rgba(255, 255, 255, .8); font-size: 15px; line-height: 20px; display: inline-block; text-align: center; border: 1px solid #0086c8; cursor: pointer; border-radius: 4px; padding: 3px 5px; margin: 3px; max-width: 800px; min-width: 30px; } .ui-share-btn:first-child { margin-left: 0px; } .ui-share-btn:hover { background-color: #f8f8f8; border-color: #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;'>Share: <a href='https://aqicn.org/sensor/gas/'>aqicn.org/sensor/gas/</a></i><br></div><div style='clear:both;margin-bottom:10px;'></div> This page contains list of Gas sensors "suitable" for ambient and outdoor Air Quality sensing, and currently under tesing by the World Air Quality Index project <b>Earth Sensing labs</b>. (<small>For a complete list of all the Air Quality Sensors test on the World Air Quality Index project, check our <a href='/sensor/'>sensor overview page</a></small>) <br> <br> The most common Gas Air pollutants are Ozone (O<sub>3</sub>), Nitrogen Dioxide (NO<sub>2</sub>), Sulphur Dioxide (SO<sub>2</sub>), and Carbon Monoxyde (CO), but it is also common to measure Hydrogen Sulphide (H<sub>2</sub>S), Methane (CH<sub>4</sub>), Benzene (C<sub>6</sub>H<sub>6</sub>)... <br> <br>  <style> ul.sensor { padding-left: 20px; } ul.sensor .info { border:1px solid #888; background-color: #eee; padding:5px; font-size: 90%; max-width: 500px; display: inline-block; } ul.sensor li.nok { color:#888; text-decoration: line-through; } ul.sensor li { font-weight: 800; } ul.sensor li:nth-child(n+2) { margin-top:20px; } </style> <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 16.269357 10.78125 15.5 C 14.30154 15.772761 18.245209 15.070028 21.71875 12.96875 A 1.0021949 1.0021949 0 1 0 20.6875 11.25 C 16.887924 13.548509 12.317006 14.000584 8.78125 13.21875 C 8.6725971 13.194724 8.5753958 13.151278 8.46875 13.125 C 10.108287 13.189898 11.88322 13.060799 13.6875 12.6875 C 16.718701 12.060355 19.36029 10.886006 21.21875 9.4375 C 23.067114 7.9968631 24.272087 6.1533076 23.875 4.21875 C 23.8732 4.20861 23.8769 4.197602 23.875 4.1875 C 23.513143 2.2541955 21.685558 1.0369822 19.4375 0.4375 C 18.307598 0.13619269 17.031654 -0.02489364 15.65625 -0.03125 z M 15.65625 1.96875 C 16.883971 1.97489 18.004902 2.1263073 18.9375 2.375 C 20.802695 2.8723854 21.754612 3.7133252 21.90625 4.5625 A 1.0001 1.0001 0 0 0 21.9375 4.625 C 22.12047 5.4788616 21.54154 6.6735055 20 7.875 C 18.45846 9.0764945 16.081299 10.145895 13.3125 10.71875 C 10.546306 11.291066 7.7660826 11.269646 5.8125 10.78125 C 4.8357087 10.537052 4.0847823 10.157122 3.625 9.78125 C 3.3682882 9.5713881 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> <style type='text/css'> section { margin-top:20px; margin-bottom: 80px; } @media only screen and (max-width: 800px) { border-top: 1px solid #ccc; } @media only screen and (min-width: 800px) { section { padding-left: 20px; border-left: 3px solid #f8f8f8; } } </style><h2><p>Ozone</p></h2><section> Ground ozone is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight. Breathing ozone can trigger a variety of health problems, especially for those with lung diseases such as asthma. Ground level ozone can also have harmful effects on sensitive vegetation and ecosystems. <br> <br> Ambient Ozone sensing is done in the range 0 ~ 500ppb (for reference 54ppb corresponds to an AQI of 50 - at 8 hours exposure, and 500 ppb corresponds to an AQI of 500 at 1 hour exposure, using the US EPA standard). <br> <br> The most common and official way to measure ground level Ozone is by UV absorption photometry (<a href='https://www.wmo.int/pages/prog/www/IMOP/publications/CIMO-Guide/Ed2008Up2010/Part-I/WMO8_Ed2008_PartI_Ch16_Up2010_en.pdf'>WMO ref</a>), The "low-cost" Ozone sensors, on the contrary, are based on electro-chemical analysis, and are therefore much less accurate than photometers. <br> <br> <ul class='sensor'> <li>Winsen MQ 131</li> <div class='info'> Manufacturer: Zhengzhou Winsen Electronics Technology Co., Ltd. <br> Cost: 60RMB. <br> Spec: <a href='/air/view/sensor/spec/o3.winsen-mq131.pdf'>Spec sheet</a>, <a href='http://www.winsen-sensor.com/products/semiconductor-gas-sensor/sensor-mq131.html'>product page</a> <br> Detection range: 10 ppb ~ 1ppm (for the low concentration version) <br> Detection accuracy: unknown. </div> <img style='display: inline-block;height:100px;' src='/air/view/images/sensors/ozone-mq131-front.png'> <div style='clear: both'></div> The MQ 131 is a electro-chemcial Ozone sensor able to detect on the range from 10 ppb to 1 ppm. <li>A3OZ EnviroceL®</li> <div class='info'> Manufacturer: City Tech <br> Cost: ? (>1000RMB) <br> Spec: <a href='http://www.citytech.com/PDF-Datasheets/a3oz.pdf'>Spec sheet</a>, <a href='http://www.citytech.com/'>product page</a> <br> Detection range: 0-10ppm <br> Detection accuracy: 20ppb. </div> <img style='display: inline-block;height:100px;' src='http://www.citytech.com/images/new_site/City_logo.png'> <div style='clear: both'></div> The A3OZ sensor is one of a range for monitoring gases at levels found in the environment. It is designed to give accurate readings of O3 or NO2 in ambient air. <li class='nok'>Sensortech Mics 2614</li> <div class='info'> Manufacturer: <a href='http://www.sgxsensortech.com/'>sgxsensortech.com</a> <br> Cost: 120RMB. <br> Spec: <a href='/air/view/sensor/spec/o3.sgx-mics2614.pdf'>Spec sheet</a>, <a href='http://www.sgxsensortech.com/sensor-selector/'>product page</a> <br> Detection range: 10 ppb ~ 1ppm <br> Detection accuracy: unknown. </div> <img style='display: inline-block;height:100px;' src='/air/view/images/sensors/ozone-mics-2614.png'> <div style='clear: both'></div> The Mics 2614 is a SMD O3 sensor able to detect on the range from 10 ppb to 1 ppm.<br> It is unfortunately discontinued since early 2016 due to supply problems with the special wafers used in manufacturing. <li class='nok'>Spec 3SP-O3-20</li> <div class='info'> Manufacturer: <a href='http://www.spec-sensors.com/'>spec-sensors.com</a> <br> Cost: 60RMB. <br> Spec: <a href='/air/view/sensor/spec/o3.spec-3sp-o3-20.pdf'>Spec sheet</a>, <a href='http://www.spec-sensors.com/product/ozone-sensor/'>product page</a> <br> Detection range: 20 ~ 20 ppm <br> Detection accuracy: unknown. </div> <img style='display: inline-block;height:100px;' src='/air/view/images/sensors/Ozone-SpecsSensor-front.png'> <div style='clear: both'></div> The Spec Sensors 3SP-O3-20 is detecting O3 in the range 0 - 20 ppm, with uknwown accuracy... - which makes it not suitable to ambient Ozone sensing. </ul> <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 16.269357 10.78125 15.5 C 14.30154 15.772761 18.245209 15.070028 21.71875 12.96875 A 1.0021949 1.0021949 0 1 0 20.6875 11.25 C 16.887924 13.548509 12.317006 14.000584 8.78125 13.21875 C 8.6725971 13.194724 8.5753958 13.151278 8.46875 13.125 C 10.108287 13.189898 11.88322 13.060799 13.6875 12.6875 C 16.718701 12.060355 19.36029 10.886006 21.21875 9.4375 C 23.067114 7.9968631 24.272087 6.1533076 23.875 4.21875 C 23.8732 4.20861 23.8769 4.197602 23.875 4.1875 C 23.513143 2.2541955 21.685558 1.0369822 19.4375 0.4375 C 18.307598 0.13619269 17.031654 -0.02489364 15.65625 -0.03125 z M 15.65625 1.96875 C 16.883971 1.97489 18.004902 2.1263073 18.9375 2.375 C 20.802695 2.8723854 21.754612 3.7133252 21.90625 4.5625 A 1.0001 1.0001 0 0 0 21.9375 4.625 C 22.12047 5.4788616 21.54154 6.6735055 20 7.875 C 18.45846 9.0764945 16.081299 10.145895 13.3125 10.71875 C 10.546306 11.291066 7.7660826 11.269646 5.8125 10.78125 C 4.8357087 10.537052 4.0847823 10.157122 3.625 9.78125 C 3.3682882 9.5713881 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> </section><h2><p>Nitrogen Dioxide</p></h2><section> NO2 primarily gets in the air from the burning of fuel. It forms from emissions from cars, trucks and buses, power plants, and off-road equipment - so it is most relevant for road-side sensing. <br> <br> Ambient NO2 sensing is done in the range 0 ~ 2000ppb (for reference 54ppb corresponds to an AQI of 50, and 2000 ppb corresponds to an AQI of 500, using the US EPA standard). <br> <br> The are at least 3 common and official methods for measuring NO2: (<a href='https://uk-air.defra.gov.uk/assets/documents/reports/cat15/0408171323_Appendix1Issue3toPhase2report.pdf'>Derfra ref</a>) The first two are based on infra-red absorbtion resp. em-radition, and the 3rd one, but also most recent, is based on the <a href='http://www.environnement-sa.com/caps-chemiluminescence-no2-measurement/'>Chemiluminescence</a> principle. The "low-cost" Ozone sensors, on the contrary, are based on electro-chemical analysis, and are therefore much less accurate than any of the 3 above methods. <br> <br> <ul class='sensor'> <li>Sensortech Mics 2714</li> <div class='info'> Manufacturer: <a href='http://www.sgxsensortech.com/'>sgxsensortech.com</a> <br> Cost: 150RMB. <br> Spec: <a href='/air/view/sensor/spec/no2.sgx-mics2714.pdf'>Spec sheet</a>, <a href='http://www.sgxsensortech.com/content/uploads/2014/08/1107_Datasheet-MiCS-2714.pdfno2.sgx-mics2714'>product page</a> <br> Detection range: 50 ppb ~ 5ppm <br> Detection accuracy: unknown. </div> <img style='display: inline-block;height:100px;' src='/air/view/images/sensors/ozone-mics-2614.png'> <div style='clear: both'></div> The Mics 2714 is a SMD Nitrogen dioxide sensor able to detect on the range from 50 ppb to 5 ppm. Note there there is another variant, the Miscs 4514, able to detect higher NO2 ranges, but the 2714 is the most suitable for Ambient NO2 sensing. <br> Unfortunatelt, the Mics 2714 is not able to detect NO2 below 50ppb (ie an AQI of 50), so that is not so usefull for places with low NO2 concentration (which is quite often the case). <li> Alpha Sense NO2 B43F</li> <div class='info'> Manufacturer: <a href='http://www.alphasense.com'>alphasense.com</a> <br> Cost: 1000RMB. <br> Spec: <a href='/air/view/sensor/spec/no2.alphasense-no2-b43f.pdf'>Spec sheet</a>, <a href='http://www.alphasense.com/index.php/products/nitrogen-dioxide/'>product page</a> <br> Detection range: 0 ppb ~ 2ppb <br> Detection accuracy: unkown. </div> <img style='display: inline-block;height:100px;' src='/air/view/images/sensors/alphasense-no2-a1-front.png'> <div style='clear: both'></div> The Alpha Sense NO2 B43F is a special low-concentration version of the NO2 familly range, detecting NO2 in the range 0 - 2 ppm, which makes it suitable for ambient sensing. <li class='nok'>Sensortech SGX EC4 20 NO2</li> <div class='info'> Manufacturer: <a href='http://www.sgxsensortech.com/'>sgxsensortech.com</a> <br> Cost: <br> Spec: <a href='/air/view/sensor/spec/no2.sgx-ec4-no2-20.pdf'>Spec sheet</a>, <a href='http://www.sgxsensortech.com/sensor-selector/#prod_579'>product page</a> <br> Detection range: 0 ppb ~ 2ppm <br> Detection accuracy: unkown. </div> <div style='clear: both'></div> The Sensortech ZE03 is detecting NO2 in the range 0 - 20 ppm, with uknwown accuracy... - which makes it not suitable to ambient NO2 sensing. <li class='nok'> Winsen ZE03</li> <div class='info'> Manufacturer: <a href='http://www.winsen-sensor.com/'>winsen-sensor.com</a> <br> Cost: <br> Spec: <a href='/air/view/sensor/spec/no2.winsen-ZE03.pdf'>Spec sheet</a>, <a href='http://www.winsen-sensor.com/d/files/PDF/Gas%20Sensor%20Module/Industrial%20Application%20Gas%20Sensor%20Module/ZE03%20Electrochemical%20Module%20V2.4.pdf'>product page</a> <br> Detection range: 0 ppb ~ 2ppm <br> Detection accuracy: unkown. </div> <div style='clear: both'></div> The Winsen ZE03 is detecting NO2 in the range 0 - 20 ppm, with uknwown accuracy... - which makes it not suitable to ambient NO2 sensing. <li class='nok'> Honeywell 4NO2-20</li> <div class='info'> Manufacturer: <a href='http://www.honeywell.com/'>honeywell.com</a> <br> Cost: 450RMB. <br> Spec: <a href='/air/view/sensor/spec/no2.honeywell-4no2-20.pdf'>Spec sheet</a>, <a href='http://www.honeywell.com.cn/en/S-Series/Product-List/CLE-Sensor/NO2'>product page</a> <br> Detection range: 0 ppb ~ 2ppm <br> Detection accuracy: 100ppb. </div> <div style='clear: both'></div> The Honeywell is fomerly knonw as Solidsense 4NO2-20. The 4NO2-20 (like the 7NO2-20) is able to detect NO2 in the range 0 to 20 ppm, with a resoliution of 100ppb - which makes it not suitable to ambient NO2 sensing. <li class='nok'> DD Scientific GS+4NO2</li> <div class='info'> Manufacturer: <a href='http://www.ddscientific.com/'>ddscientific.com</a> <br> Cost: 460RMB. <br> <a href='/air/view/sensor/spec/no2.gs-4no2.pdf'>Spec sheet</a>, <a href='http://www.ddscientific.com/uploads/5/7/1/3/57136893/gs_4no2_datasheet___.pdf ()'>product page</a> <br> Detection range: 0 ppb ~ 30ppm <br> Detection accuracy: 200ppb. </div> <div style='clear: both'></div> The DD GS+4NO2 is detecting NO2 in the range 0 - 30 ppm, with accuracy of ±200 ppb - this is too sensitive for ambient NO2 sensing. </ul> <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 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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='border:1px solid #ccc;text-align:center;padding:8px;background-color:#eee;'>For the list of all air quality sensors, check the <a class='citysync' href='/sensor/'>Sensor Overview</a> page</div><br><div style='height:1px;background-color:#aaaaaa;width:220px;margin-top:5px;'></div><div id="disqus_thread_title" onclick="showDisqus();" style="margin:20px 5px;cursor:pointer;color:#888;"><svg fill="#888888" style="float:left;margin-right:5px;" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px" viewBox="0 0 511.999 511.999" width=32 heigh=32 xml:space="preserve"> <path d="M372.29,50.758H28.831C12.933,50.758,0,63.691,0,79.588v206.056c0,15.897,12.933,28.831,28.831,28.831h22.271v76.71 c0,4.884,2.942,9.289,7.456,11.159c1.494,0.62,3.064,0.92,4.62,0.92c3.144,0,6.232-1.228,8.543-3.538l85.251-85.25h17.104 c6.671,0,12.078-5.407,12.078-12.078c0-6.672-5.409-12.079-12.078-12.079c0,0-22.69,0.016-22.927,0.04 c-2.812,0.191-5.572,1.349-7.722,3.498l-68.169,68.169c0,0-0.021-60.392-0.06-60.705c-0.545-6.166-5.717-11.002-12.024-11.002 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></div> <script type="text/javascript"> function showDisqus() { document.getElementById("disqus_thread_title").style.display="none"; var disqus_identifier = "httpaqicnorgsensorgas"; var disqus_url = "http:\/\/aqicn.org\/sensor\/gas\/"; var disqus_title = "Air Quality Gas Sensor analysis"; var dsq = document.createElement("script"); dsq.type = "text/javascript"; dsq.async = true; dsq.src = "//aqicn.disqus.com/embed.js"; (document.getElementsByTagName("head")[0] || document.getElementsByTagName("body")[0]).appendChild(dsq); }; </script> </div></div></div><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;;'>About the Air Quality and Pollution Measurement:</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>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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transition: all 0.3s ease-in 0s; } .onoffswitch-checkbox:checked + .onoffswitch-label .onoffswitch-inner { margin-left: 0; } .onoffswitch-checkbox:checked + .onoffswitch-label .onoffswitch-switch { right: 0px; } </style> <style> #settingsdiv-copy { margin:20px; } #settingsdiv-outer { padding-bottom:10px; position:fixed; z-index: 100003; } #settingsdiv { xdisplay: none; xwidth:200px; xheight:120px; overflow-y: scroll; max-height: 300px; font-size:15px; padding:2px 10px; background-color:#0086c8; -webkit-box-shadow: 1px 1px 2px 0 rgba(0,0,0,0.5); border-radius:3px; -moz-border-radius:3px; -webkit-border-radius:3px; border:3px solid #fff; color:#fff; } #settingsdiv h2 { font-size:20px; } #settings-lang { padding: 5px; } #settings-lang a:hover { text-decoration: none; } #settings-lang .item:hover { background-color: #eee; color: black; } #settings-lang .item:hover .name { color: black; } #settings-lang .item { max-width: 450px; padding: 2px; } #settings-lang .name span { font-size: 16px; } #settings-lang .name { font-size:18px; color: white; font-variant: small-caps; } #settings-lang .flag { vertical-align: text-bottom; display:inline-block; } #settings-lang select { font-size: 18px; } </style> <div id='settingsdiv-outer'> <div id='settingsdiv' > <div onclick='settingsMenu.close()' style='cursor:pointer;border-bottom:1px solid #ccccf8;padding-top:12px;'> <svg height="24px" viewBox="0 0 512 512" width="24px" style='float:right;fill:white;'> <path d="M74.966,437.013c-99.97-99.97-99.97-262.065,0-362.037c100.002-99.97,262.066-99.97,362.067,0 c99.971,99.971,99.971,262.067,0,362.037C337.032,536.998,174.968,536.998,74.966,437.013z M391.782,120.227 c-75.001-74.985-196.564-74.985-271.534,0c-75.001,74.985-75.001,196.55,0,271.535c74.97,74.986,196.533,74.986,271.534,0 C466.754,316.775,466.754,195.212,391.782,120.227z M188.124,369.137l-45.251-45.266l67.876-67.877l-67.876-67.876l45.251-45.267 L256,210.743l67.877-67.892l45.25,45.267l-67.876,67.876l67.876,67.877l-45.25,45.266L256,301.245L188.124,369.137z"/> </svg> <h2>Settings</h2> </div> <br> <center> <div id='settings-lang'> Language Settings: <br> <div class='sprite-isprt-web-gb flag'></div> <div class='sprite-isprt-web-cn flag'></div> <div class='sprite-isprt-web-jp flag'></div> <div class='sprite-isprt-web-kr flag'></div> <div class='sprite-isprt-web-pl flag'></div> <br> <select onchange='location.href = this.value'> <option value='https://aqicn.org/sensor/gas/' selected>English</option><option value='https://aqicn.org/sensor/gas/cn/' >简体中文 - Chinese</option><option value='https://aqicn.org/sensor/gas/jp/' >日本 - Japanese</option><option value='https://aqicn.org/sensor/gas/es/' >español - Spanish</option><option value='https://aqicn.org/sensor/gas/kr/' >한국의 - Korean</option><option value='https://aqicn.org/sensor/gas/ru/' >русский - Russian</option><option value='https://aqicn.org/sensor/gas/hk/' >繁體中文 - Traditional Chinese</option><option value='https://aqicn.org/sensor/gas/fr/' >Francais - French</option><option value='https://aqicn.org/sensor/gas/pl/' >Polski - Polish</option><option value='https://aqicn.org/sensor/gas/de/' >Deutsch - German</option><option value='https://aqicn.org/sensor/gas/pt/' >Português - Portuguese</option><option value='https://aqicn.org/sensor/gas/vn/' >Tiếng Việt - Vietnamese</option><option value='https://aqicn.org/sensor/gas/it/' >Italiano - Italian</option><option value='https://aqicn.org/sensor/gas/id/' >bahasa Indonesia - Indonesian</option><option value='https://aqicn.org/sensor/gas/nl/' >Nederlands - Dutch</option><option value='https://aqicn.org/sensor/gas/fa/' >فارسی - Persian</option><option value='https://aqicn.org/sensor/gas/th/' >ภาษาไทย - Thai</option><option value='https://aqicn.org/sensor/gas/hu/' >Magyar - Hungarian</option><option value='https://aqicn.org/sensor/gas/el/' >Ελληνικά - Greek</option><option value='https://aqicn.org/sensor/gas/ro/' >Română - Romanian</option><option value='https://aqicn.org/sensor/gas/bg/' >български - Bulgarian</option><option value='https://aqicn.org/sensor/gas/ur/' >اردو - Urdu</option><option value='https://aqicn.org/sensor/gas/hi/' >हिंदी - Hindi</option><option value='https://aqicn.org/sensor/gas/ar/' >العربية - Arabic</option><option value='https://aqicn.org/sensor/gas/sr/' >Српски - Serbian</option><option value='https://aqicn.org/sensor/gas/bn/' >বাংলা - Bangla</option><option value='https://aqicn.org/sensor/gas/bs/' >босански - Bosnian</option><option value='https://aqicn.org/sensor/gas/hr/' >hrvatski - Croatian</option><option value='https://aqicn.org/sensor/gas/tr/' >Türkçe - Turkish</option><option value='https://aqicn.org/sensor/gas/uk/' >українська - Ukrainian</option><option value='https://aqicn.org/sensor/gas/cs/' >čeština - Czech</option><option value='https://aqicn.org/sensor/gas/be/' >беларускі - Belarusian</option></select> </div> <br> <table> <tr><td> <center> <i>Temperature unit:</i><br> <span style='font-size:18px'> <span style='display:;' id='settings-temp-label-on'>Celcius</span> <span style='display:none;' id='settings-temp-label-off'>Fahrenheit</span> </span> </center> </td><td> <div class="onoffswitch" onclick='settingsMenu.click("temp")'> <input type="checkbox" name="onoffswitch" class="onoffswitch-checkbox" id="settings-temp" checked > <label class="onoffswitch-label" for="myonoffswitch"> <span class="onoffswitch-inner"></span> <span class="onoffswitch-switch"></span> </label> </div> </table> </center> <br> </div> <div style='display:none;height:0px;' id='settingsdiv-arrow'><div style='width: 0; height: 0; border: 7px solid transparent;top:0px;border-top: 7px solid #fff;position:relative;;margin-left:100px;'></div></div> </div> <script> function CSettingsMenu() { var self=this; var isInit = false; var timeout = null; var isPopup = false; this.show = function() { log("show!"); if (isPopup) { this.close(); return; } isPopup = true; $("#settingsdiv-arrow").hide(); $("#settingsdiv").show(); var pos = $("#footer-settings-img").offset(); $("#settingsdiv-outer").css({ left: "0px", width: "100%", bottom: "30px" }); $("#settingsdiv").css({ width: "100%", textAlign: "center", boxSizing: "border-box" }); }; this.close = function() { log("close!"); $("#settingsdiv").hide(); isPopup = false; }; this.onmouseover = function() { if (isPopup) return; if (!footer || !footer.isFloating()) return; if (getWindowWidth()<800) return; if (!isInit) { $('#settingsdiv-outer').show() .mouseleave(function(){ self.onmouseout(); }) .mouseenter(function(){ self.onmouseover(); }); display("temp"); isInit = true; } if (timeout) clearTimeout(timeout); timeout = null; var pos = $("#footer-settings-img").offset(); var px = (pos.left+6-100); $("#settingsdiv-outer").css({ left: px + "px", bottom: (30) + "px" }); $("#settingsdiv").show(); $("#settingsdiv-arrow").delay(150).show(); var tb = document.getElementById("settingsdiv").getBoundingClientRect(), w =getWindowWidth(); var ml = Math.min((w-tb.right-2),0); $("#settingsdiv-outer").css({left:(px+ml)+"px"}); }; this.onmouseout = function() { if (isPopup) return; isShown = false; if (timeout) clearTimeout(timeout); timeout = setTimeout(function(){ $("#settingsdiv").slideUp(200); $("#settingsdiv-arrow").hide(); },150); }; this.click = function(item) { var status = store.get('aqicn-settings-'+item); store.set('aqicn-settings-'+item,status==1?2:1); display(item); if (item=="temp") convertTemperature(); }; this.val = function(item) { var status = store.get('aqicn-settings-'+item); return status!=1; }; var display = function(item) { var status = store.get('aqicn-settings-'+item); if (status==1) { $("#settings-"+item+"-label-off").show(); $("#settings-"+item+"-label-on").hide(); } else { $("#settings-"+item+"-label-on").show(); $("#settings-"+item+"-label-off").hide(); } var o = document.getElementById("settings-"+item); if (o) o.checked = status!=1; }; document.getElementById('settingsdiv-outer').addEventListener('touchmove', function(e) { e.preventDefault(); }, false); return this; } var settingsMenu = new CSettingsMenu(); </script> <script type="text/javascript"> fitLine(".link",.9); </script> <script src='https://aqicn.org/air-cache/jquery-3.4.1.min.js?_=20191127.152416' type='text/javascript'></script> <script type="text/javascript"> function initTime() { if (isMobileUA) return; function setTimeText() { var monthNames = [ "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" ]; var dayNames= ["Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"]; var newDate = new Date(); newDate.setDate(newDate.getDate()); var od = document.getElementById("ClockTime"); if (od) od.innerHTML = dayNames[newDate.getDay()] + " " + monthNames[newDate.getMonth()] + ' ' + newDate.getDate() + ', ' + newDate.getFullYear(); var minutes = new Date().getMinutes(); var hours = new Date().getHours(); var time = ( hours < 10 ? "0" : "" ) + hours; time += ":"+( minutes < 10 ? "0" : "" ) + minutes; var ot = document.getElementById("ClockTime"); if (ot) ot.innerHTML = time; } setInterval( function() { setTimeText() }, 1000*60*15 ); setTimeText(); }; aqi18n.register('aqi-implication-0-50',"Air quality is considered satisfactory, and air pollution poses little or no risk");aqi18n.register('aqi-level-0-50',"Good");aqi18n.register('aqi-implication-50-100',"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.");aqi18n.register('aqi-level-50-100',"Moderate");aqi18n.register('aqi-implication-100-150',"Members of sensitive groups may experience health effects. The general public is not likely to be affected.");aqi18n.register('aqi-level-100-150',"Unhealthy for sensitive groups");aqi18n.register('aqi-level-100-150-html',"<div style='font-size:66%'>Unhealthy for sensitive groups<\/div>");aqi18n.register('aqi-implication-150-200',"Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects");aqi18n.register('aqi-level-150-200',"Unhealthy");aqi18n.register('aqi-implication-200-300',"Health warnings of emergency conditions. 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