The Illinois Environmental Protection Agency has issued an air pollution action day for most of northeastern Illinois on Wednesday, which will stay in effect throughout the night.

An air pollution action day is declared when weather conditions are such that widespread ozone and or particulate levels are expected to be at or above the Unhealthy for Sensitive Groups (USG) category of the Air Quality Index (AQI) for multiple days, the National Weather Service said.

Ozone is expected to be the primary pollutant of concern, the weather service said. Active children and adults, especially people with pulmonary or respiratory disease such as asthma, should limit prolonged outdoor activity.

Area residents are urged to reduce pollution levels. Air quality forecasts, current air quality, and tips on how you can reduce your emissions can be found at www.airnow.gov.