Woodstock, Illinois Air Quality
Woodstock has a median AQI of 43, earning an air quality grade of A- — excellent air quality that ranks better than 39% of US cities. Air quality has remained relatively stable over the past decade. Ground-level ozone is the primary concern, typically peaking on warm sunny days due to vehicle and industrial emissions. In 2025, Woodstock recorded 180 good air quality days (66% of monitored days) and 12 unhealthy days.
Population: 26,147 • County: McHenry
Current AQI
Quick Facts
| Current AQI | 15 — Good |
| Air Quality Grade | A- |
| Median AQI (2025) | 43 |
| vs. U.S. Cities | Better than 39% |
| Primary Pollutant | Ozone |
| Unhealthy Days/Year | 12 |
| 10-Year Trend | → Stable |
| Data Source | EPA AQS (historical) · AirNow (live) |
Health Recommendation
Air quality is satisfactory, and air pollution poses little or no risk.
It's a great day to be active outside!
5-Day AQI Forecast
Last 90 Days
Current Pollutant Levels
Real-time data from EPA AirNow
Local Air Quality Context
Air quality data for Woodstock is sourced from the CARY monitoring area, located approximately 12 miles from city center. This EPA-certified station continuously tracks ground-level ozone, the primary driver of air quality alerts in this area.
Woodstock tends to see elevated PM2.5 readings during fall and winter months when temperature inversions trap pollutants near the surface. Wood burning, vehicle exhaust, and reduced wind speeds compound the effect. Residents with respiratory conditions should monitor forecasts closely between November and February.
AQI Trend (10 Years)
Air Quality Days by Year
Woodstock Median AQI by Year
Annual EPA air quality data for Woodstock — median AQI, day-category breakdown, and primary pollutant per year.
| Year | Median AQI | Good Days | Unhealthy Days | Max AQI | Primary Pollutant |
|---|---|---|---|---|---|
| 2025 | 43 | 180 | 12 | 165 | Ozone |
| 2024 | 43 | 245 | 1 | 108 | PM2.5 |
| 2023 | 49 | 191 | 21 | 230 | PM2.5 |
| 2022 | 47 | 199 | 3 | 126 | PM2.5 |
| 2021 | 49 | 187 | 2 | 105 | PM2.5 |
| 2020 | 47 | 192 | 9 | 147 | PM2.5 |
| 2019 | 52 | 161 | 2 | 126 | PM2.5 |
| 2018 | 46 | 213 | 8 | 122 | Ozone |
| 2017 | 44 | 226 | 3 | 133 | PM2.5 |
| 2016 | 44 | 241 | 6 | 129 | PM2.5 |
Source: EPA Air Quality System (AQS) annual summaries. "Unhealthy Days" includes Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, and Hazardous categories.
2025 Air Quality Summary
Primary Pollutant Days (2025)
Days when each pollutant was the primary driver of AQI. Learn about pollutants →
Frequently Asked Questions About Woodstock Air Quality
What is the air quality in Woodstock today?
The current AQI in Woodstock is 15, rated "Good". Air quality is good — outdoor activity is safe for everyone today. Air quality is satisfactory, and air pollution poses little or no risk.
Is air quality in Woodstock getting better or worse?
Air quality in Woodstock has been stable. The median AQI has dropped 1 points (from 44 in 2016 to 43 in 2025).
What is the most common air pollutant in Woodstock?
Ozone is the primary air pollutant in Woodstock, responsible for 154 days (57% of monitored days) in 2025. Ground-level ozone forms when sunlight reacts with emissions from vehicles and industry, typically peaking on hot summer afternoons.
How many unhealthy air days does Woodstock have per year?
In 2025, Woodstock recorded 66% good air quality days (180 days) out of 272 monitored days. There were 11 Unhealthy for Sensitive Groups days and 1 Unhealthy days (AQI above 100). The highest single-day AQI recorded was 165.
What air quality grade does Woodstock receive?
Woodstock receives an air quality grade of A-, placing it better than 39% of US cities. This is based on a median AQI of 43 in 2025, with 180 good air quality days. The EPA monitors air quality in this area continuously using certified monitoring stations.
Air Quality Grade
Better than 39% of US cities
Nearby Cities
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National Rankings
See how Woodstock compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for Woodstock
Ozone is Woodstock's primary pollutant. Standard HEPA filters don't capture ozone molecules — you need activated carbon or PECO technology to chemically break them down. We highlight those units here.
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