The state Department of Environmental Quality declared Tuesday an ozone action day because air pollution could get high enough in the afternoon to cause health problems for some people in the Baton Rouge region.

Parishes involved in the alert include East Baton Rouge, West Baton Rouge, Iberville, Livingston, Ascension and Pointe Coupee. Children and adults, especially those with respiratory illnesses and the elderly, should avoid long periods of outdoor activity.

On Monday, at least two air monitors in the region — at LSU and in Port Allen — registered air quality in the “orange” level, indicating ozone levels were unhealthy for sensitive people.

Unlike other air pollution, ozone isn’t directly released by industries, vehicles or other sources. Instead, ozone forms when volatile organic compounds and nitrogen oxides from vehicles, industry and other sources combine in the air during hot, sunny days. When there is little wind to dissipate the pollution, the ozone can accumulate and cause breathing or other health problems for vulnerable people.

In addition to limiting afternoon outdoor recreation, residents in the six-parish area are asked to limit activities that could lead to ozone formation. That includes waiting to refuel vehicles, mow the grass or use off-road vehicles until after 6 p.m. People can also carpool and drive less during the day to help reduce vehicle emissions. Industries also participate by limiting some activities that could lead to releases of ozone-causing pollution.

Currently, the region meets the federal standard for ozone; however, the U.S. Environmental Protection Agency is expected at the end of the year to release recommendations for a tougher standard.

Follow Amy Wold on Twitter, @awold10.