Map Web Service: Real-time Air Quality Tile API

Posted on September 18th 2015
Share: aqicn.org/faq/2015-09-18/map-web-service-real-time-air-quality-tile-api


Map Overlay Process
(Attribution: Essentials of
Geographic Information Systems
)

We have been recently cooperating with quite a few more EPAs worlwide. Among all the requests which we have had, it is actually to provide a Web Map Service so that the EPA themselves can include the real-time Air Quality data onto the map from their website.

One of the obvious advantages of using such a map web service from us is to benefit from the transboundary data which we are curating, i.e. a world wide Air Quality information is provided without country boundary limits.

The second advantage is not only that this is a free service, but it is also completely compatible with standard map technologies from google, bing or leaflet, which allows a quick and easy integration with any existing website.


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Tile Map Service Endpoint

The tile map server is available from the url https://tiles.waqi.info/tiles/{aqi}/{z}/{x}/{y}.png, where aqi refers for the type of marker to be plotted, which can be:
  • usepa-aqi: Plots markers based on the composite AQI calculated with the US EPA standard.
  • usepa-pm25: PM2.5 based AQI - if a station does not have PM2.5 reading, then it is not plotted.
  • usepa-10: Same as above, but for PM10.
  • usepa-o3: Same as above, but for Ozone (based on the 1 hour breakpoints).
  • usepa-no2: Same as above, but for Nitrogen Dioxide.
  • usepa-so2: Same as above, but for Sulfur Dioxide.
  • usepa-co: Same as above, but for Carbon Monoxide.
  • asean-pm10: Asean PM10 raw PM10 concentration (explanations).
Below is the example for the 6 individual pollutants for South China.

Web-Service usage conditions

The map webservice is provided for free, under the condition of reasonable usage limits and acceptable usage policy. The tiles are currently refreshed every 15 minutes (and up to 1 hour in case of high traffic).

Note that our server capacity is limited, so we reserve the right to pause the service at any time, for instance to performance server maintenance. If you need a more stable integration, contact us to find a proper solution, such as setting-up a dedictated server.

Last you also need to specify your own token ID as an extra argument to the tile service endpoint, like token=_TOKEN_ID_ in the following url: https://tiles.waqi.info/tiles/{aqi}/{z}/{x}/{y}.png?token=_TOKEN_ID_. You can request your own token ID from this page. You just need to provide a valid email, and you can get your own token within a minute.

Web-Service usage restrictions

When using the service, please do not forget to provide the attribution to the World Air Quality Index project as well as the EPA providing the data (if you use the map service to show data from a specicic location or source). You can get the full list of all the EPA from this link.

As a matter of fact, do not act like the World Resource Institute (WRI): they were scrapping our entire data feed, and republishing the data on their own project website without giving any single attribution for our work... That's not quite ok when you know that they get funded up to 80 millions USD each year. Don't believe us? Check this snapshot.

Future extensions

We are already working on extending this webservice to provide more configuations. For instance:
  • To support for more standards other than the US EPA, such as eucaqi-xxx for the European Common Air Quality Index, innaqi-xxx for the Indian National Air Quality Index , raw-xxx for the unconverted raw data, etc.
  • More indicators such as the wind (both for the current wind speed and wind direction), as well as forecasted ventilation index [1] which can be extrememly usefull for forecasting.
  • Support for kriging geo-statistical surface estimation - i.e. heatmap like interpolations (picture on the right) which can be usefull for lower density monitoring network.
  • Support for 24 hours and 8 hours data averaging . Our map are currenly based on 1 hour averaging, but longer averaging period are useful for epidemilogicial studies.
  • Support for GeoJSON based tile rendering, allowing the customization of markers and color scale, as well as a better integration with tools like tuftjs.org.


Note that to support more AQI standards and tile configurations, we need to increase our server capacity (both processing power and Storage), for which we will require sponsorship. If you are working for one of the large cloud company, or for instance Google or Microsoft and reading this message, then why not considering making your company environmentally-friendly (combatting air pollution by promoting citizen awarness), and sponsoring part of the needed server extra capacity? That would not only help us, but also help the whole community of researchers, scientists, statisticians and epidemiologies working with environmental data and sciences.

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Sample code: Integration with Leaflet

Leaflet is an extremely cool light-weight open-source JavaScript library for mobile-friendly interactive maps, created by Vladimir Agafonkin of MapBox.

Sample code:
  
<div  id='map'  style='height:380px;'  />  
<link  rel="stylesheet"  href="http://cdn.leafletjs.com/leaflet-0.7.5/leaflet.css"  />  
<script  src="http://cdn.leafletjs.com/leaflet-0.7.5/leaflet.js"></script>  
  
<script>  
      var  OSM_URL  =  'http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png';  
      var  OSM_ATTRIB  =  '&copy;  <a  href="http://openstreetmap.org/copyright">OpenStreetMap</a>  contributors';  
      var  osmLayer  =  L.tileLayer(OSM_URL,  {attribution:  OSM_ATTRIB});  
  
      var  WAQI_URL    =  "https://tiles.waqi.info/tiles/usepa-aqi/{z}/{x}/{y}.png?token=_TOKEN_ID_";  
      var  WAQI_ATTR  =  'Air  Quality  Tiles  &copy;  <a  href="http://waqi.info">waqi.info</a>';  
      var  waqiLayer  =  L.tileLayer(WAQI_URL,  {attribution:  WAQI_ATTR});  
  
      var  map  =  L.map('map').setView([51.505,  -0.09],  11);  
      map.addLayer(osmLayer).addLayer(waqiLayer);  
</script>

Sample code: Integration with Google

Google maps are quite convinient and free up to 25,000 API calls a day. Note that google maps is available in china, but the maps API script needs to be loaded from google.cn (http://maps.google.cn/maps/api/js) instead of the regular https://maps.googleapis.com/maps/api/js url.

  
  
<div  id='map'  style='height:380px;'  />  
<script  src="https://maps.googleapis.com/maps/api/js"></script>  
  
<script>  
      var  map  =  new  google.maps.Map(document.getElementById('map'),  {  
                  center:  new  google.maps.LatLng(51.505,  -0.09),  
                  mapTypeId:  google.maps.MapTypeId.ROADMAP,  
                  zoom:  11  
              });  
  
                              var  t  =  new  Date().getTime();  
      var  waqiMapOverlay  =  new  google.maps.ImageMapType({  
                  getTileUrl:  function(coord,  zoom)  {  
                            return  'https://tiles.waqi.info/tiles/usepa-aqi/'  +  zoom  +  "/"  +  coord.x  +  "/"  +  coord.y  +  ".png?token=_TOKEN_ID_";  
                  },  
                  name:  "Air  Quality",  
        });  
  
      map.overlayMapTypes.insertAt(0,waqiMapOverlay);  
</script>

Sample code: Integration with Microsoft Bing Maps

Bing maps are actually quite cool, and also using Here base map for some countries. There are still quite a lot of web site based on Microsoft Maps (and especially in the domain of Air Quality and weather).

  
  
<div  id='map'  style='height:380px;'    style='position:relative;'/>  
<script  type="text/javascript"  src="https://ecn.dev.virtualearth.net/mapcontrol/mapcontrol.ashx?v=7.0&s=1"></script>  
  
<script>  
      var  map  =  new  Microsoft.Maps.Map(document.getElementById('map'),    
                  {    center:  new  Microsoft.Maps.Location(51.505,  -0.09),  zoom:11  }  );  
  
      var  waqiTileOptions  =  {  uriConstructor:  function  (quadkey)  {  
            return  "https://tiles.waqi.info/tiles/usepa-aqi/"  +  quadkey.levelOfDetail+"/"+quadkey.x+"/"+  quadkey.y  +  ".png?token=_TOKEN_ID_";  
      }  };  
      var  waqiTileSource  =  new  Microsoft.Maps.TileSource(waqiTileOptions);  
      var  waqiTilelayer  =  new  Microsoft.Maps.TileLayer({  mercator:  waqiTileSource  });  
      map.entities.push(waqiTilelayer);  
</script>



[1] Also refered as venting index or cumulated wind power


Click here to see all the FAQ entries
  • Nitrogen Dioxyde (NO2) in our atmosphere
  • Ozone AQI Scale update
  • Kriging Interpolation

  • Read or publish comments (they rely on Disqus)

    大気汚染指数の測定方法:

    大気汚染レベルについて

    指数大気質指数の分類(米国)健康影響 / カテゴリ粒子状物質(PM10,PM2.5)
    0 - 50良い - Good通常の活動が可能なし
    51 -100並 - Moderate特に敏感な者は、長時間又は激しい屋外活動の減少を検討非常に敏感な人は、長時間または激しい活動を減らすよう検討する必要がある。
    101-150敏感なグループにとっては健康に良くない - Unhealthy for Sensitive Groups心臓・肺疾患患者、高齢者及び子供は、長時間又は激しい屋外活動を減少心疾患や肺疾患を持つ人、高齢者、子供は、長時間または激しい活動を減らす必要がある。
    151-200健康に良くない - Unhealthy上記の者は、長時間又は激しい屋外活動を中止
    すべての者は、長時間又は激しい屋外活動を減少
    心疾患や肺疾患を持つ人、高齢者、子供は、長時間または激しい活動を中止する必要がある。それ以外の人でも、長時間または激しい活動を減らす必要がある。
    201-300極めて健康に良くない - Very Unhealthy上記の者は、すべての屋外活動を中止
    すべての者は、長時間又は激しい屋外活動を中止
    心疾患や肺疾患を持つ人、高齢者、子供は、全ての屋外活動を中止する必要がある。それ以外の人でも、長時間または激しい活動を中止する必要がある。
    300+危険 - Hazardous上記の者は、屋内に留まり、体力消耗を避ける
    すべての者は、屋外活動を中止
    全ての人が屋外活動を中止する必要がある。特に、心疾患や肺疾患を持つ人、高齢者、子供は、屋内に留まって激しい活動を避け静かに過ごす必要がある。
    (Reference: see wikipedia,and cn.emb-japan.go.jp/)

    大気汚染についての更なる詳細をお知りになりたい方は、WikipediaAirNowを参照してください。

    北京在住の医師Richard Saint Cyr氏による大変役に立つ健康上のアドバイスは、 www.myhealthbeijing.com をご覧ください。


    使用上の注意: すべての大気質データは公開時点では妥当性が担保されていないため、これらのデータは予告なしに修正することがあります。 世界大気質指数プロジェクトは、この情報の内容を編集に最善の注意を尽くしておりますが、いかなる状況においても World Air Quality Index プロジェクトチームまたはそのエージェントは、このデータの供給によって直接的または間接的に生じる損失や損害について責任を負いません。



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    Temperature unit:
    Celcius