Metro area air quality · 2025

Quincy, IL-MO

Median AQI 38 (Good). 94.7% of monitored days rated Good across this metro's EPA monitoring network.

38
Median AQI
94.7%
Good-air days
0
Unhealthy days
94%
Cleaner than US metros

Quincy, IL-MO posted a 2025 median AQI of 38 (Good) with 94.7% Good days

According to the U.S. EPA Air Quality System, the Quincy, IL-MO CBSA recorded a median AQI of 38 across 244 monitored days in 2025, with 94.7% rated Good and 0 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 Quincy, IL-MO CBSA's 94.7% Good-day share places it cleaner than 94% of US metros in 2025.
Closest median-AQI peer
Appleton, WI (72.3% Good, median AQI 38) is the closest nationwide median-AQI peer to Quincy, IL-MO.
2020–2025 Good-day shift
Quincy, IL-MO's Good-day share moved +4.5 points from 2020 to 2025 (median AQI +0).
Median AQI
Median AQI: 38

Aggregated from EPA Air Quality System (2025), 244 monitored days. EPA AQS →

The verdict

Quincy, IL-MO sits in the upper Good-day tercile among EPA CBSA metros on this site (94.7% of 244 monitored days). On the EPA scale the metro runs good, among the cleanest 10% of US metros, with a median AQI of 38 and 94.7% of 244 monitored days in the Good band.

38
median AQI · Good
94.7%
days rated Good
94%
cleaner than US metros
71
worst single reading

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

Annual release change

What changed in the 2025 EPA annual release

2024 → 2025
  • Quincy, IL-MO metro's Good-day share rose from 90.1% to 94.7% between the 2024 and 2025 EPA annual releases, a change of +4.5 percentage points.
  • Quincy, IL-MO metro's peak single-day AQI fell from 97 to 71 between the 2024 and 2025 EPA annual releases, a change of -26 points.
  • Quincy, IL-MO metro's median AQI fell from 42 to 38 between the 2024 and 2025 EPA annual releases, a change of -4 points.

Compared against 233 monitored days in 2024 and 244 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

Quincy, IL-MO sits in the upper Good-day tercile among EPA CBSA metros on this site (94.7% of 244 monitored days). Signature read: 94.7% Good-day share (high tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 38 over 244 measured days in 2025 (Good / Excellent). The monitored-day split lands at 231 Good (95%), 13 Moderate (5%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 49; the highest single-day reading hit 71 (Moderate).

Across 2020–2025, Good-day share shifted +4.5 points and median AQI moved +0 (improving). No Unhealthy-tier days appear in this annual dataset. Metros with comparable AQI profiles include Appleton, WI (72.3% good, AQI 38); Billings, MT (86.3% good, AQI 38); Burlington-South Burlington, VT (87.7% good, AQI 38).

Best and worst city air quality →

Air Quality Summary

Median AQI

38

Good

Good Days

94.7%

231 of 244 days

Max AQI

71

Moderate

Health Grade

Excellent

90th pct: 49

AQI Day Breakdown (2025)

Distribution of 244 monitored days across EPA AQI categories.

Good

231

95%

Moderate

13

5%

USG

0

0%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Excellent

The Quincy, IL-MO metro area's air quality is rated Excellent based on 94.7% 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 Quincy, IL-MO metro compare?

How Quincy, IL-MO compares

Good-day share better than typical
Quincy, IL-MO 94.7%
Appleton, WI 72.3%
Typical US metro 70.6%
Median AQI better than typical
Quincy, IL-MO 38
Appleton, WI 38
Typical US metro 41
Unhealthy days / yr better than typical
Quincy, IL-MO 0
Appleton, WI 6
Typical US metro 1

5-Year Air Quality Trend

Air quality is improving in the Quincy, IL-MO metro. Highest Good-day share: 2022 (97.0%, 230 of 237 monitored days).

Year Good Moderate Unhealthy Median AQI
2020 220 24 0 38
2021 219 23 0 40
2022 230 7 0 39
2023 184 49 0 43
2024 210 23 0 42
2025 231 13 0 38

Metros with a similar median AQI

CBSA peers nationwide whose annual median AQI sits near Quincy, IL-MO (38).

Appleton, WI

Median AQI 38 · 72.3% Good-day share

38

Billings, MT

Median AQI 38 · 86.3% Good-day share

38

Burlington-South Burlington, VT

Median AQI 38 · 87.7% Good-day share

38

Charlottesville, VA

Median AQI 38 · 81.0% Good-day share

38

Corning, NY

Median AQI 38 · 83.3% Good-day share

38

Dickinson, ND

Median AQI 38 · 82.7% Good-day share

38

Metros with similar unhealthy-day exposure

A second relationship type: metros whose unhealthy-or-worse day count is closest to Quincy, IL-MO's 0 (independent of median AQI).

Aberdeen, SD

0 unhealthy-or-worse days · median AQI 27

27

Aberdeen, WA

0 unhealthy-or-worse days · median AQI 22

22

Adrian, MI

0 unhealthy-or-worse days · median AQI 41

41

Akron, OH

0 unhealthy-or-worse days · median AQI 45

45

Albany, GA

0 unhealthy-or-worse days · median AQI 46

46

Albany, OR

0 unhealthy-or-worse days · median AQI 27

27

Frequently Asked Questions

How many unhealthy air days does Quincy, IL-MO have? ▼
In 2025, the Quincy, IL-MO metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 71.
What is the air quality in the Quincy, IL-MO metro area? ▼
The Quincy, IL-MO metro area has a median Air Quality Index (AQI) of 38, rated "Good." 94.7% of monitored days (231 out of 244) had good air quality in 2025.
Is air quality in Quincy, IL-MO getting better or worse? ▼
Air quality in the Quincy, IL-MO 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: 2022 at 97.0% (230 of 237 days). Lowest qualifying Good-day share: 2023 at 79.0% (184 of 233 days).
What does AQI 38 mean for health? ▼
An AQI of 38 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 Quincy, IL-MO compare to other metro areas? ▼
The Quincy, IL-MO metro has 94.7% good air days. Similar metros: Appleton, WI (72.3% good), Billings, MT (86.3% good), Burlington-South Burlington, VT (87.7% good).
What is the 90th percentile AQI for Quincy, IL-MO? ▼
The 90th percentile AQI for the Quincy, IL-MO metro area is 49, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 71 (Moderate).

Data Sources

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