Illinois(IL)
Air quality overview and monitoring data — 2025
554
Monitoring Sites
10,903
Active Monitors
50
Counties with Data
144
Cities Monitored
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County Air Quality
| County | Median AQI ▲ | 90th %ile | Max AQI | Good | Moderate | USG | Unhealthy |
|---|---|---|---|---|---|---|---|
| Effingham | 35 | 46 | 71 | 202 | 9 | 0 | 0 |
| Jo Daviess | 35 | 47 | 87 | 215 | 13 | 0 | 0 |
| Clark | 36 | 49 | 87 | 246 | 21 | 0 | 0 |
| Macoupin | 37 | 49 | 105 | 247 | 24 | 1 | 0 |
| Adams | 38 | 49 | 71 | 201 | 12 | 0 | 0 |
| Lake | 40 | 67 | 108 | 167 | 30 | 3 | 0 |
| Rock Island | 41 | 64 | 167 | 184 | 87 | 0 | 2 |
| Winnebago | 41 | 71 | 169 | 178 | 79 | 5 | 1 |
| Sangamon | 42 | 61 | 142 | 193 | 77 | 3 | 0 |
| Hamilton | 43 | 62 | 98 | 179 | 90 | 0 | 0 |
| McHenry | 43 | 79 | 165 | 180 | 80 | 11 | 1 |
| Champaign | 44 | 64 | 138 | 174 | 96 | 3 | 0 |
| DuPage | 44 | 76 | 158 | 167 | 100 | 5 | 1 |
| Jersey | 44 | 67 | 156 | 195 | 68 | 2 | 1 |
| Macon | 44 | 67 | 141 | 174 | 96 | 3 | 0 |
| McLean | 44 | 69 | 154 | 175 | 94 | 3 | 1 |
| Randolph | 44 | 62 | 161 | 182 | 89 | 0 | 1 |
| Saint Clair | 44 | 63 | 161 | 192 | 103 | 2 | 1 |
| Will | 45 | 74 | 156 | 162 | 106 | 4 | 1 |
| Kane | 46 | 83 | 165 | 166 | 98 | 8 | 1 |
| Peoria | 47 | 67 | 154 | 156 | 110 | 2 | 2 |
| Madison | 48 | 73 | 260 | 168 | 132 | 3 | 1 |
| Cook | 53 | 94 | 168 | 111 | 139 | 19 | 5 |
Pollutant Trends
Ozone
No data available
PM2.5
No data available
PM10
No data available
CO
No data available
NO2
No data available
SO2
No data available