The combination of heat, humidity and calm winds are contributing to an air quality alert day.
An air quality alert is issued when pollution levels could cause problems for some groups, such as people with asthma or heart disease, the elderly, very young children, and pregnant women. Douglas County Health Department spokesman Phil Rooney says air quality alert days are rare in Omaha, with only about four or five a year.
Rooney says anyone in the groups sensitive to air pollution should avoid outdoor activities if possible. You can help reduce the amount of pollution by carpooling, riding a bicycle, or taking the bus to and from work.
An excessive heat warning continues through Wednesday evening.