* Increasing AQI indicates a decreasing air quality. In interpreting data, consider that PM10 monitoring started in 1988 and PM2.5 monitoring was phased in between 1999 and 2001. When tracking trends that include PM2.5, the EPA includes years 2000 and later.
Years Available: 1980–2019
Permanent Link: http://data.sagepub.com/sagestats/4137
General Notes: *Median value gives the value for the "average" county for this metric, the 50th percentile of all counties reporting data. **Number of days on which measurements from any monitoring site in the county were reported to the AQS database.