The National Weather Service (NWS) has issued an Air Quality Alert for Chicago, effective through tonight.
The alert comes after the Illinois Environmental Protection Agency’s (EPA) declared Wednesday, May 27 an “Air Pollution Action Day.”
But what is an Air Pollution Action Day and what does it mean for you?
Here’s a breakdown.
Chicago Air Pollution Action Day
The EPA declares an Air Pollution Action Day for Chicago when weather conditions allow ozone and particulates to reach unsafe levels for sensitive groups.
Ozone is a reactive gas which forms in our atmosphere due to natural and man-made phenomena, according to the EPA.
While not all Ozone is bad, ground-level Ozone can cause adverse health effects when inhaled, and lead to what we know as “smog” in urban areas.
Chicago’s air quality was in the “moderate” range as of Wednesday morning, according to data from Airnow.
A moderate reading means that the air quality may be unsafe for sensitive populations.
The NWS notes that active adults an children, especially those with conditions like asthma, should limit their time outdoors.