The National Weather Service has issued an air quality alert that will be in effect all day today.

According to the National Weather Service, "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' category of the air quality index."

The National Weather Service advises that "active children and adults, and especially people with pulmonary or respiratory disease such as asthma, should limit outdoor activity."

The air quality alert is in effect until tonight for all of northern Illinois, including Lake, Cook and McHenry Counties.