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RankingsIllinoisWorst air quality

Counties with the Worst Air Quality in Illinois

The top 23 of 23 Illinois counties on GIS Map, ranked by median Air Quality Index, counting only counties that host an EPA air monitor.

#CountyMedian AQI
1Cook County
54
2Madison County
49
3St. Clair County
46
4DuPage County
45
5Champaign County
44
6Hamilton County
44
7McLean County
44
8Peoria County
44
9Rock Island County
44
10Will County
44
11Macon County
43
12McHenry County
43
13Winnebago County
43
14Adams County
42
15Jersey County
42
16Kane County
42
17Effingham County
41
18Sangamon County
41
19Lake County
40
20Randolph County
40
21Clark County
36
22Jo Daviess County
36
23Macoupin County
35

Source: EPA Air Quality Index annual summary (2024). All counties with data are ranked. Estimates carry margins of error.

Citing this page: GIS Map, “Counties with the Worst Air Quality in Illinois”, https://gismap.land/rankings/illinois/worst-air-quality-counties. Figures from EPA Air Quality Index annual summary (2024).

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