Click on the AIRNow Website to obtain current information about the air quality in Philadelphia. The Air Quality Index (AQI) is a color coding system as seen in the chart below.  Using formulas created by the EPA, data for the pollutants: ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, and particulate matter, are converted into a score ranging from 0 to 500. Values exceeding 100 trigger "Action Days" where you are advised to take precautions to protect yourself from health effects. The highest of the pollutant scores is reported as the overall air quality rating for Philadelphia for a given day.
Air Quality Index (AQI) Values Levels of Health Concern Colors
When the AQI is in this range: ...air quality conditions are: ...as symbolized by this color:
0 to 50 Good Green
51 to 100 Moderate Yellow
101 to 150 Unhealthy for Sensitive Groups Orange
151 to 200 Unhealthy Red
201 to 300 Very Unhealthy Purple
301 to 500 Hazardous Maroon

 
 
Additional information may be obtained through the Air Management Services (AMS) Website. AMS is the local air pollution control agency for the City of Philadelphia and provides services to achieve healthy air quality through the prevention and control of air pollution and air pollution nuisances.