McLean, Illinois Air Quality
McLean County, Illinois (IL)
↑ Worseningover 10 years
How McLean, Illinois Air Quality Compares
McLean, Illinois's median AQI of 50is 22% worse than the national average of 41. Air quality has worsened by 13 AQI points over the past decade. The area averages 4 unhealthy air days per year. The primary pollutant of concern is Fine Particulate Matter (PM2.5).
McLean, Illinois Air Quality: The Full Picture
McLean, Illinois (McLean County) holds an AirHistory Air Quality Grade of D (poor, scoring 49 out of 100), built from 10 years of EPA Air Quality System monitoring. Its median AQI rose 13 points between 2014 (37) and 2023 (50), and the five-year median now sits at 48 — inside the "Good" band on the EPA scale.
The pollutant driving most of the area's AQI readings is Fine Particulate Matter (PM2.5). In 2023, it set the daily AQI on 253 of 365 monitored days (69% of the year), making it the controlling pollutant for the D grade. The single worst reading logged that year hit an AQI of 289 (Very Unhealthy), while the 90th-percentile day — the level the dirtiest 10% of days reach — came in at 74.
In 2023, McLean County recorded 184 "Good" air days (50% of the 365 days with valid AQI data), 168 "Moderate" days, and 13 days at "Unhealthy for Sensitive Groups" or above. Over the most recent five years on record, monitors logged 19 days that crossed into "Unhealthy for Sensitive Groups" or worse — about 4 per year.
The decade-long trend is worsening: median AQI has been climbing by roughly 1.39 points per year. The cleanest year in the record was 2014 (median AQI 37), and the most polluted was 2018 (median AQI 52). Because the data come straight from federally certified EPA monitors, these figures track the Illinois county the monitors physically sit in rather than a city boundary.
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10-Year AQI Trend
The solid line shows the median AQI each year. The dashed line shows the 90th percentile (worst 10% of days). Air quality in this area has been declining over the past decade.
Air Quality Day Breakdown
Number of days per year in each EPA AQI category. Green = Good (AQI 0-50), Yellow = Moderate (51-100), Orange = Unhealthy for Sensitive Groups (101-150), Red = Unhealthy or worse (151+).
Year-by-Year Data
| Year | Median AQI | 90th Pct | Max AQI | Good Days | Moderate | Unhealthy+ | Pollutant |
|---|---|---|---|---|---|---|---|
| 2023 | 50 | 74 | 289 | 184 | 168 | 13 | PM2.5 |
| 2022 | 47 | 63 | 129 | 207 | 156 | 2 | PM2.5 |
| 2021 | 48 | 63 | 107 | 191 | 173 | 1 | PM2.5 |
| 2020 | 48 | 61 | 136 | 207 | 154 | 3 | PM2.5 |
| 2019 | 49 | 65 | 100 | 187 | 177 | 0 | PM2.5 |
| 2018 | 52 | 67 | 108 | 169 | 195 | 1 | PM2.5 |
| 2017 | 48 | 61 | 100 | 201 | 163 | 0 | PM2.5 |
| 2016 | 39 | 61 | 108 | 283 | 82 | 1 | Ozone |
| 2015 | 37 | 55 | 90 | 304 | 59 | 0 | Ozone |
| 2014 | 37 | 58 | 100 | 312 | 51 | 0 | Ozone |
What This Means for McLean County Residents
McLean, Illinois has received an Air Quality Grade of D (49/100) based on a decade of monitoring data from the EPA's air quality monitoring program. The current median AQI of 50 falls in the "Good" range.
Concerning trends show air quality has been declining, with the median AQI rising by 13 points over the monitoring period. This could be driven by increased development, wildfire smoke, or industrial activity.
The primary pollutant affecting this area is Fine Particulate Matter (PM2.5). Over the past 5 years, this area has averaged 4 unhealthy air quality days per year, days when sensitive groups (children, elderly, those with respiratory conditions) should limit outdoor activity. The American Lung Association's State of the Air report provides additional context on long-term health risks from air pollution exposure.
Related Cities in Illinois
Frequently Asked Questions
McLean, Illinois has a current median AQI of 50, which falls in the "Good" range. The area has received an Air Quality Grade of D (49/100) based on 10 years of EPA monitoring data.
Air quality in McLean, Illinois is worsening over the past decade. The median AQI has changed by +13 points from 2014 to 2023.
McLean, Illinois averages 4 unhealthy air quality days per year over the past 5 years. On these days, sensitive groups including children, the elderly, and those with respiratory conditions should limit outdoor activity.
The primary pollutant affecting McLean, Illinois is Fine Particulate Matter (PM2.5). This is the dominant contributor to elevated AQI readings in the McLean County area.
McLean, Illinois averages 4 unhealthy air days per year. This is relatively low, making it a reasonable choice for asthma sufferers. The primary pollutant is Fine Particulate Matter (PM2.5), which is a known asthma trigger.
With a median AQI of 50 (Good), outdoor exercise in McLean, Illinois is generally safe year-round. McLean, Illinois averages 4 days per year when athletes should move workouts indoors.