NASHVILLE (AP) - The Nashville and Knoxville regions are under the summer season's first air quality alerts.

The Tennessee Department of Environment and Conservation issued an alert for ozone for all of Friday for Metro Nashville and a dozen surrounding counties. A similar alert was in effect from 8 a.m.-8 p.m. Friday for 10 counties around Knoxville. The "code orange alerts" mean the concentration of ozone in the region is expected to reach or exceed unhealthful standards.

While most healthy people probably won't be affected, breathing the air could be harmful to children, the elderly and people with breathing difficulties. .

Ozone forms when sunlight reacts with emissions from auto exhaust and industrial plant discharges. Carpooling is encouraged and unnecessary car trips should be avoided.