Air Quality
Moderate
Water Violations
9
Active Contamination
18
Active Permits
2
Air quality in Cook County is rated moderate with a median AQI of 53 (274 days measured in 2025). 2 community water systems serve the area, with 9 recent violations in the last 5 years. 59 contamination sites are tracked, including 18 open leaking tank incidents.
Air Quality — Cook County (2025)i
AQSThe Air Quality Index measures how clean or polluted the air is on a given day. AQI is reported at the county level. A score of 0-50 is considered good; 51-100 is moderate; above 100 may be unhealthy for sensitive groups.
Median AQI
PM2.5 Daysi
145Ozone Daysi
97Drinking Wateri
SDWISPublic water systems registered to serve this area. Community systems (CWS) provide water to residents year-round. Violations indicate a system failed to meet federal drinking water standards.
Community Systemsi
2Active Systemsi
2Recent Violationsi
9Industrial Monitoringi
Wastewater & Stormwater Permits (NPDES)i
NPDESContamination Sitesi
Contaminated sites tracked by the EPA and state agencies. Superfund sites are the most seriously contaminated locations. Brownfields are former industrial properties being cleaned up for reuse. LUST sites have confirmed leaks from underground storage tanks.