What are we measuring?
The Air Quality Index (AQI) is an index for reporting daily air quality, which is calculated based on the pollutant concentration of criteria air pollutants regulated by the Clean Air Act. The higher the AQI value, the greater the level of air pollution and the greater the health concern.
AQI value of 101-150 indicates air quality condition is unhealthy for Sensitive Groups, which include children, elderly and people with cardiovascular and respiratory diseases. 
Why are we measuring it?
Local air quality affects how you live and breathe. The AQI provides a simple index for the health effects you may experience due to unhealthy air quality. 
How are we doing?
Since 2016, the number of bad air quality days has continued to drop moving from 12 days in 2016 to 4 days in 2018. 
The chart below compares the number of days per year with AQI between 101 to 150 in Fulton County with 10 benchmark counties across the nation. For 2018, Fulton County had fewer days with unhealthy air quality for sensitive groups than Milwaukee County, WI, Shelby County, TN, Travis County, TX, Franklin County, OH, Mecklenburg County, NC, Cuyahoga County, OH and Allegheny County, PA.