KNOXVILLE, Tenn. (WATE) — The Air Quality for Tuesday and Wednesday in several counties across East Tennessee is in the Unhealthy for Sensitive Groups Category, according to The Tennessee Department of Environment and Conservation.

A Code Orange Health Advisory has been issued for the greater Knoxville Metropolitan Area and Great Smoky Mountains National Park. This includes Anderson, Blount, Campbell, Grainger, Jefferson, Knox, Loudon, Morgan, Sevier, Roane and Union counties.

While the general public is not likely to be affected, people with asthma or lung disease, older adults and children are at a greater risk of exposure to ozone. People in these vulnerable group should limit their outdoor activities as well as avoid any strenuous activities outdoors.

The U.S. Air Quality Index (AQI) is divided into six levels sorted by color. A Code Orange Air Quality Alert was first issued on Monday and has since been extended.

The Environmental Protection Agency establishes an Air Quality Index for five major air pollutants regulated by the Clean Air Act: ground-level ozone, particle pollution, carbon monoxide, sulfur dioxide, and nitrogen dioxide.