Metro area air quality · 2025

Peoria, IL

Median AQI 47 (Good). 57.8% of monitored days rated Good across this metro's EPA monitoring network.

47
Median AQI
57.8%
Good-air days
2
Unhealthy days
20%
Cleaner than US metros

Aggregated from EPA Air Quality System (2025), 270 monitored days. EPA AQS →

The verdict

The Peoria, IL metro runs good on the EPA scale, among the more polluted US metros, a median AQI of 47 with 57.8% of 270 monitored days in the Good band.

47
median AQI · Good
57.8%
days rated Good
20%
cleaner than US metros
154
worst single reading

2 days reached Unhealthy or worse across the metro's monitors in 2025.

Insights: Peoria, IL metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 47 over 270 measured days in 2025, which corresponds to a Good band and a Moderate metro-wide health grade. The monitored-day split lands at 156 Good days (58%), 110 Moderate (41%), and 2 Unhealthy-for-Sensitive-Groups (1%). The 90th-percentile AQI finished at 67 while the highest single-day reading hit 154 (Unhealthy). Metro residents averaged roughly 17.3 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, good days shifted by -91 and the median AQI moved +3 points, which classifies the multi-year trajectory as worsening. The metro recorded 2 unhealthy-or-worse days combined, on those days the EPA recommends that sensitive groups limit prolonged outdoor exertion, and many schools and athletic programs adjust outdoor activity accordingly. Metros with comparable AQI profiles include Ardmore, OK (65.3% good, AQI 47); Baltimore-Columbia-Towson, MD (62.2% good, AQI 47); Boise City, ID (64.7% good, AQI 47).

Air Quality Summary

Median AQI

47

Good

Good Days

57.8%

156 of 270 days

Max AQI

154

Unhealthy

Health Grade

Moderate

90th pct: 67

AQI Day Breakdown (2025)

Distribution of 270 monitored days across EPA AQI categories.

Good

156

58%

Moderate

110

41%

USG

2

1%

Unhealthy

2

1%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Moderate

The Peoria, IL metro area's air quality is rated Moderate based on 57.8% good air days. There were 2 unhealthy days in 2025 when outdoor activity should be limited.

Air quality is acceptable most days, but 2 days reached "Unhealthy for Sensitive Groups" and peak AQI reached 154. Sensitive groups should monitor real-time conditions at AirNow.gov.

How does the Peoria, IL metro compare?

How Peoria, IL compares

Good-day share worse than US avg
Peoria, IL 57.8%
Ardmore, OK 65.3%
US average 71.3%
Median AQI worse than US avg
Peoria, IL 47
Ardmore, OK 47
US average 41
Unhealthy days / yr worse than US avg
Peoria, IL 2
Ardmore, OK 2
US average 1

5-Year Air Quality Trend

Air quality is worsening in the Peoria, IL metro. Best year: 2020 (247 good days).

Year Good Moderate Unhealthy Median AQI
2020 247 116 0 44
2021 181 179 0 50
2022 181 138 0 48
2023 187 131 1 48
2024 236 108 0 44
2025 156 110 2 47

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to Peoria, IL.

Ardmore, OK

AQI 47 · 65.3% good

47

Baltimore-Columbia-Towson, MD

AQI 47 · 62.2% good

47

Boise City, ID

AQI 47 · 64.7% good

47

Cheyenne, WY

AQI 47 · 69.8% good

47

Chico, CA

AQI 47 · 66.1% good

47

Columbus, GA-AL

AQI 47 · 58.8% good

47

More Air Quality Data

Explore EPA air quality rankings and guides across U.S. metros and counties.

Cleanest Metro Areas

U.S. metros ranked by their share of Good air-quality days.

Worst Air Quality

Counties and metros with the most unhealthy air days.

All Metro Areas

Annual AQI by CBSA for every monitored U.S. metro area.

Best and Worst City Air

What drives urban air quality and how metro areas compare.

Air Quality Guides

Frequently Asked Questions

What is the air quality in the Peoria, IL metro area? ▼
The Peoria, IL metro area has a median Air Quality Index (AQI) of 47, rated "Good." 57.8% of monitored days (156 out of 270) had good air quality in 2025.
How many unhealthy air days does Peoria, IL have? ▼
In 2025, the Peoria, IL metro area recorded 2 unhealthy air days (2 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 154.
Is air quality in Peoria, IL getting better or worse? ▼
Air quality in the Peoria, IL metro is worsening based on 5-year trends (2020-2025). Best year: 2020 with 247 good days. Worst year: 2025 with 156 good days.
What does AQI 47 mean for health? ▼
An AQI of 47 is "Good", air quality is satisfactory and poses little or no health risk. This is the best category on the EPA's AQI scale.
What is the 90th percentile AQI for Peoria, IL? ▼
The 90th percentile AQI for the Peoria, IL metro area is 67, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 154 (Unhealthy).
How does Peoria, IL compare to other metro areas? ▼
The Peoria, IL metro has 57.8% good air days. Similar metros: Ardmore, OK (65.3% good), Baltimore-Columbia-Towson, MD (62.2% good), Boise City, ID (64.7% good).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset, 2020–2025. See our methodology for how AQI, median, and coverage figures are computed.

Read our methodology , how this data is sourced, computed, and verified.

Source: U.S. EPA Air Quality System (AQS) Annual AQI by CBSA summary files (metro-level) · 2020–2025

Every figure on PlainAir is rendered directly from EPA AQS air-quality monitoring data, no number is typed in by an editor. This page draws directly on EPA AQS air-quality monitoring data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.