Metro area air quality · 2025

Rockford, IL

Median AQI 40 (Good). 68.7% of monitored days rated Good across this metro's EPA monitoring network.

40
Median AQI
68.7%
Good-air days
1
Unhealthy days
42%
Cleaner than US metros

Rockford, IL posted a 2025 median AQI of 40 (Good) with 68.7% Good days

According to the U.S. EPA Air Quality System, the Rockford, IL CBSA recorded a median AQI of 40 across 355 monitored days in 2025, with 68.7% rated Good and 1 unhealthy or worse. This is an annual metro comparison, not a live advisory.

Data source EPA Air Quality System (AQS)

Cleaner than US metros
The Rockford, IL CBSA's 68.7% Good-day share places it cleaner than 42% of US metros in 2025.
Closest median-AQI peer
Altoona, PA (76.9% Good, median AQI 40) is the closest nationwide median-AQI peer to Rockford, IL.
2020–2025 Good-day shift
Rockford, IL's Good-day share moved +13.5 points from 2020 to 2025 (median AQI -7).
Median AQI
Median AQI: 40

Aggregated from EPA Air Quality System (2025), 355 monitored days. EPA AQS →

The verdict

Rockford, IL's peak reading 169 is in the upper max-AQI tercile among CBSA metros here. On the EPA scale the metro runs good, more polluted than the median US metro, with a median AQI of 40 and 68.7% of 355 monitored days in the Good band.

40
median AQI · Good
68.7%
days rated Good
42%
cleaner than US metros
169
worst single reading

1 day reached Unhealthy or worse across the metro's monitors in 2025.

Annual release change

What changed in the 2025 EPA annual release

2024 → 2025
  • Rockford, IL metro's peak single-day AQI rose from 119 to 169 between the 2024 and 2025 EPA annual releases, a change of +50 points.
  • Rockford, IL metro's median AQI fell from 43 to 40 between the 2024 and 2025 EPA annual releases, a change of -3 points.
  • Rockford, IL metro's Unhealthy-category days rose from 0 to 1 between the 2024 and 2025 EPA annual releases, a change of +1 days.

Compared against 358 monitored days in 2024 and 350 in 2025. These are arithmetic differences between two stored EPA annual summaries, not a cause claim or a live advisory.

National release changes Two-year CSV

Rockford, IL's peak reading 169 is in the upper max-AQI tercile among CBSA metros here. Signature read: peak AQI 169 (high tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 40 over 355 measured days in 2025 (Good / Moderate). The monitored-day split lands at 244 Good (69%), 105 Moderate (30%), and 5 Unhealthy-for-Sensitive-Groups (1%). The 90th-percentile AQI finished at 67; the highest single-day reading hit 169 (Unhealthy).

Across 2020–2025, Good-day share shifted +13.5 points and median AQI moved -7 (improving). The annual record contains 1 day at Unhealthy or worse. Metros with comparable AQI profiles include Altoona, PA (76.9% good, AQI 40); Beaver Dam, WI (72.3% good, AQI 40); Bismarck, ND (76.7% good, AQI 40).

Health effects of air pollution →

Air Quality Summary

Median AQI

40

Good

Good Days

68.7%

244 of 355 days

Max AQI

169

Unhealthy

Health Grade

Moderate

90th pct: 67

AQI Day Breakdown (2025)

Distribution of 355 monitored days across EPA AQI categories.

Good

244

69%

Moderate

105

30%

USG

5

1%

Unhealthy

1

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Moderate

The Rockford, IL metro area's air quality is rated Moderate based on 68.7% good air days. There were 1 unhealthy days in 2025 when outdoor activity should be limited.

Air quality is acceptable most days, but 5 days reached "Unhealthy for Sensitive Groups" and peak AQI reached 169. Sensitive groups should monitor real-time conditions at AirNow.gov.

How does the Rockford, IL metro compare?

How Rockford, IL compares

Good-day share worse than typical
Rockford, IL 68.7%
Altoona, PA 76.9%
Typical US metro 70.6%
Median AQI better than typical
Rockford, IL 40
Altoona, PA 40
Typical US metro 41
Unhealthy days / yr about typical
Rockford, IL 1
Altoona, PA 0
Typical US metro 1

5-Year Air Quality Trend

Air quality is improving in the Rockford, IL metro. Highest Good-day share: 2025 (69.7%, 244 of 350 monitored days).

Year Good Moderate Unhealthy Median AQI
2020 205 160 0 47
2021 190 170 0 49
2022 237 126 0 43
2023 167 178 1 52
2024 249 109 0 43
2025 244 105 1 40

Metros with a similar median AQI

CBSA peers nationwide whose annual median AQI sits near Rockford, IL (40).

Altoona, PA

Median AQI 40 · 76.9% Good-day share

40

Beaver Dam, WI

Median AQI 40 · 72.3% Good-day share

40

Bismarck, ND

Median AQI 40 · 76.7% Good-day share

40

Cape Coral-Fort Myers, FL

Median AQI 40 · 76.4% Good-day share

40

College Station-Bryan, TX

Median AQI 40 · 68.5% Good-day share

40

Fallon, NV

Median AQI 40 · 85.2% Good-day share

40

Metros with similar unhealthy-day exposure

A second relationship type: metros whose unhealthy-or-worse day count is closest to Rockford, IL's 1 (independent of median AQI).

Ann Arbor, MI

1 unhealthy-or-worse days · median AQI 41

41

Bangor, ME

1 unhealthy-or-worse days · median AQI 33

33

Baraboo, WI

1 unhealthy-or-worse days · median AQI 35

35

Bartlesville, OK

1 unhealthy-or-worse days · median AQI 44

44

Beaumont-Port Arthur, TX

1 unhealthy-or-worse days · median AQI 52

52

Bellingham, WA

1 unhealthy-or-worse days · median AQI 31

31

Frequently Asked Questions

What is the 90th percentile AQI for Rockford, IL? ▼
The 90th percentile AQI for the Rockford, IL metro area is 67, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 169 (Unhealthy).
How many unhealthy air days does Rockford, IL have? ▼
In 2025, the Rockford, IL metro area recorded 1 unhealthy air days (1 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 169.
What is the air quality in the Rockford, IL metro area? ▼
The Rockford, IL metro area has a median Air Quality Index (AQI) of 40, rated "Good." 68.7% of monitored days (244 out of 355) had good air quality in 2025.
Is air quality in Rockford, IL getting better or worse? ▼
Air quality in the Rockford, IL metro is improving across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2025 at 69.7% (244 of 350 days). Lowest qualifying Good-day share: 2023 at 48.3% (167 of 346 days).
What does AQI 40 mean for health? ▼
An AQI of 40 is "Good", air quality is satisfactory and poses little or no health risk. This is the best category on the EPA's AQI scale.
How does Rockford, IL compare to other metro areas? ▼
The Rockford, IL metro has 68.7% good air days. Similar metros: Altoona, PA (76.9% good), Beaver Dam, WI (72.3% good), Bismarck, ND (76.7% good).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset for Rockford, IL, 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, Rockford, IL · 2020–2025