Criteria Pollutants

The federal government set standards for six commom outdoor air pollutants, also known as criteria pollutants: carbon monoxide, nitrogen dioxide, sulfur dioxide, ozone, particulate matter, and lead.  These pollutants are lead gasolineconsidered to be the most widespread nationally and the most immediately dangerous to human health, the environment, and can damage property.  Communities are required to meet the federal health standards for all six of the criteria pollutants, but are only required to continually monitor for those which appear to need testing in that area as indicated by historical data, trends, and known emissions.

Chattanooga is currently required to monitor for ozone and particulate matter, and maintains a network of monitoring sites throughout the county for this purpose.

The Bureau uses the data from the monitoring sites to generate a Daily Air Quality Report, based on EPA's Air Quality Index (AQI).  The AQI is a scale designed by the EPA to standardize the method for reporting air quality nationwide.  In Hamilton County, the daily air quality level is determined by the highest pollutant for that day.

Get more information on the Daily Air Quality Report.