Metro area air quality · 2025

Janesville-Beloit, WI

Median AQI 42 (Good). 72.8% of monitored days rated Good across this metro's EPA monitoring network.

42
Median AQI
72.8%
Good-air days
0
Unhealthy days
49%
Cleaner than US metros

Aggregated from EPA Air Quality System (2025), 92 monitored days. EPA AQS →

The verdict

The Janesville-Beloit, WI metro runs good on the EPA scale, more polluted than the median US metro, a median AQI of 42 with 72.8% of 92 monitored days in the Good band.

42
median AQI · Good
72.8%
days rated Good
49%
cleaner than US metros
93
worst single reading

No day crossed into the Unhealthy tier across the metro's monitors in 2025.

Insights: Janesville-Beloit, WI metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 42 over 92 measured days in 2025, which corresponds to a Good band and a Moderate metro-wide health grade. The monitored-day split lands at 67 Good days (73%), 25 Moderate (27%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 64 while the highest single-day reading hit 93 (Moderate). Metro residents averaged roughly 21.8 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, good days shifted by -125 and the median AQI moved +4 points, which classifies the multi-year trajectory as worsening. The metro avoided any Unhealthy-tier days entirely, an outcome that typically reflects favorable wind patterns, lower industrial density, or effective regional emission controls. Metros with comparable AQI profiles include Albany-Schenectady-Troy, NY (66.3% good, AQI 42); Bismarck, ND (75.8% good, AQI 42); Bloomington, IN (70.1% good, AQI 42).

Air Quality Summary

Median AQI

42

Good

Good Days

72.8%

67 of 92 days

Max AQI

93

Moderate

Health Grade

Moderate

90th pct: 64

AQI Day Breakdown (2025)

Distribution of 92 monitored days across EPA AQI categories.

Good

67

73%

Moderate

25

27%

USG

0

0%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Moderate

The Janesville-Beloit, WI metro area's air quality is rated Moderate based on 72.8% good air days. No unhealthy air days were recorded in 2025.

Air quality is generally acceptable. Unusually sensitive people should monitor real-time conditions at AirNow.gov during high-pollution events.

How does the Janesville-Beloit, WI metro compare?

How Janesville-Beloit, WI compares

Good-day share better than US avg
Janesville-Beloit, WI 72.8%
Albany-Schenectady-Troy, NY 66.3%
US average 71.3%
Median AQI worse than US avg
Janesville-Beloit, WI 42
Albany-Schenectady-Troy, NY 42
US average 41
Unhealthy days / yr better than US avg
Janesville-Beloit, WI 0
Albany-Schenectady-Troy, NY 0
US average 1

5-Year Air Quality Trend

Air quality is worsening in the Janesville-Beloit, WI metro. Best year: 2020 (192 good days).

Year Good Moderate Unhealthy Median AQI
2020 192 15 0 38
2021 173 32 0 41
2022 184 18 0 39
2023 131 52 2 46
2024 171 32 0 41
2025 67 25 0 42

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to Janesville-Beloit, WI.

Albany-Schenectady-Troy, NY

AQI 42 · 66.3% good

42

Bismarck, ND

AQI 42 · 75.8% good

42

Bloomington, IN

AQI 42 · 70.1% good

42

Cape Coral-Fort Myers, FL

AQI 42 · 74.4% good

42

Daphne-Fairhope-Foley, AL

AQI 42 · 72.2% good

42

Decatur, AL

AQI 42 · 81.1% good

42

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 Janesville-Beloit, WI metro area? ▼
The Janesville-Beloit, WI metro area has a median Air Quality Index (AQI) of 42, rated "Good." 72.8% of monitored days (67 out of 92) had good air quality in 2025.
How many unhealthy air days does Janesville-Beloit, WI have? ▼
In 2025, the Janesville-Beloit, WI metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 93.
Is air quality in Janesville-Beloit, WI getting better or worse? ▼
Air quality in the Janesville-Beloit, WI metro is worsening based on 5-year trends (2020-2025). Best year: 2020 with 192 good days. Worst year: 2025 with 67 good days.
What does AQI 42 mean for health? ▼
An AQI of 42 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 Janesville-Beloit, WI? ▼
The 90th percentile AQI for the Janesville-Beloit, WI metro area is 64, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 93 (Moderate).
How does Janesville-Beloit, WI compare to other metro areas? ▼
The Janesville-Beloit, WI metro has 72.8% good air days. Similar metros: Albany-Schenectady-Troy, NY (66.3% good), Bismarck, ND (75.8% good), Bloomington, IN (70.1% 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.