An air quality alert has been issued for parts of the Chicago area, but what’s causing issues this week?
According to the National Weather Service, the alert will remain in effect through Wednesday night in McHenry, Lake, Kane, DuPage, Kendall, Grundy, Cook and Will counties in Illinois, as well as Lake, Porter, Newton and Jasper counties in Indiana.
So what is causing the degraded air quality?
Unlike in most instances when airborne particulates are the root cause of the issue, such as from wildfire smoke, this alert has been triggered by excessive amounts of ground-level ozone, according to the National Weather Service.
While ozone naturally occurs in the upper levels of the atmosphere, it can also be created closer to the surface, causing air quality issues for sensitive groups.
That ozone is formed when cars, power plants, chemical plants and other sources emit pollutants into the air. Those pollutants then interact with sunlight, and that can help to quickly degrade air quality and trigger alerts.
During such air quality alerts, active children and adults, especially those with pulmonary or respiratory diseases such as asthma, are encouraged to limit prolonged outdoor activity.
Residents are also being urged to help reduce pollutant levels. They can do so by limiting car trips or by combining errands. Refueling vehicles in the evening can also help prevent pollutants from entering the atmosphere and interacting with sunlight, as can reducing the use of gas-powered lawn equipment during the heat of the day.
More information can be found on the EPA’s website.
As for when air quality could improve, winds are expected to shift back off the lake after a cool front goes through the area, and temperatures will then likely cool behind that front, though some residual pollutants could remain in the air.
