The poor air quality continues to prevail in Illinois as Canadian wildfire smoke migrates south into the U.S. As a result, the Illinois Environmental Protection Agency has issued an Air Pollution Action Day for Friday, Aug. 1. Here's what we know.

Health officials from Minnesota to Maine have issued alerts warning of poor air quality from wildfires burning in Canada. People are advised to limit outdoor exposure.

An Illinois 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 for all or almost all of Illinois.