Insights: Rock Island County, Illinois. EPA monitors recorded a median Air Quality Index of 41 across 365 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 244 (67%) fell in the Good band (AQI 0–50), 119 (33%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 61, while the worst single-day peak hit 167 (Unhealthy). Residents averaged about 20.1 clean-air days per 30-day window during the monitoring year.

The full pollutant mix ranks as PM2.5 (242 days), Ozone (123 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by +0.9 points and the median AQI moved -2 points, placing the multi-year trajectory at stable. The annual record contains 2 days at Unhealthy or worse. On those days, the EPA recommends that sensitive groups limit prolonged outdoor exertion. Nearby counties show comparable readings: Adams (94.7% good, AQI 38); Champaign (65.8% good, AQI 43); Clark (93.8% good, AQI 33); Cook (40.8% good, AQI 53); DuPage (63.8% good, AQI 42); Effingham (95.5% good, AQI 35).