PENNSYLVANIA (WHTM) — Due to Canadian wildfires, most of Pennsylvania has been shrouded in a thick layer of smoke. This is causing air quality to plummet in many locations in Pennsylvania and around the northeast.

The way air quality is measured is by the Air Quality Index or AQI. The AQI has six categories ranging from Good to Hazardous.

According to, the AQI is measured on a scale of zero to 500. The higher the number, the worse the air is. For example, an AQI of 50 is in a good category, whereas an AQI of 350 is considered very unhealthy.

As quoted from the EPA, below is a chart of AQI colors, values, and descriptions of air quality.

Daily AQI ColorLevels of ConcernValues of IndexDescription of Air Quality
GreenGood0 to 50Air quality is satisfactory, and air pollution poses little or no risk.
YellowModerate51 to 100Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.
OrangeUnhealthy for Sensitive Groups101 to 150Members of sensitive groups may experience health effects. The general public is less likely to be affected.
RedUnhealthy151 to 200Some members of the general public may experience health effects; members of sensitive groups may experience more serious health effects.
PurpleVery Unhealthy201 to 300Health alert: The risk of health effects is increased for everyone.
MaroonHazardous301 and higherHealth warning of emergency conditions: everyone is more likely to be affected.

Air quality reports conducted by the Pennsylvania Department of Environmental Protection are updated hourly at half-past the hour. They can be found here. offers an interactive map where users can type in their city, state, or zip code to see the AQI in their area. You can click here to see the map, as well as where the smoke is across the country and specific regions.