http://www.helium.com/knowledge/232965-how-to-read-the-epas-air-quality-index-aqi.xml Helium.com > Environmental Awareness > How to read the EPA's air quality index (AQI) en-us Copyright Helium.com Thu, 23 Apr 2009 02:45:27 GMT Thu, 23 Apr 2009 02:45:27 GMT