Metro area air quality · 2025

Lewiston-Auburn, ME

Median AQI 34 (Good). 85.2% of monitored days rated Good across this metro's EPA monitoring network.

34
Median AQI
85.2%
Good-air days
0
Unhealthy days
78%
Cleaner than US metros

Lewiston-Auburn, ME posted a 2025 median AQI of 34 (Good) with 85.2% Good days

According to the U.S. EPA Air Quality System, the Lewiston-Auburn, ME CBSA recorded a median AQI of 34 across 365 monitored days in 2025, with 85.2% 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 Lewiston-Auburn, ME CBSA's 85.2% Good-day share places it cleaner than 78% of US metros in 2025.
Closest median-AQI peer
Arkadelphia, AR (96.7% Good, median AQI 34) is the closest nationwide median-AQI peer to Lewiston-Auburn, ME.
2020–2025 Good-day shift
Lewiston-Auburn, ME's Good-day share moved -5.2 points from 2020 to 2025 (median AQI +0).
Median AQI
Median AQI: 34

Aggregated from EPA Air Quality System (2025), 365 monitored days. EPA AQS →

The verdict

Lewiston-Auburn, ME sits in the upper Good-day tercile among EPA CBSA metros on this site (85.2% of 365 monitored days). On the EPA scale the metro runs good, cleaner than most US metros, with a median AQI of 34 and 85.2% of 365 monitored days in the Good band.

34
median AQI · Good
85.2%
days rated Good
78%
cleaner than US metros
112
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
  • Lewiston-Auburn, ME metro's Good-day share fell from 92.6% to 85.7% between the 2024 and 2025 EPA annual releases, a change of -6.9 percentage points.
  • Lewiston-Auburn, ME metro's peak single-day AQI rose from 77 to 112 between the 2024 and 2025 EPA annual releases, a change of +35 points.
  • Lewiston-Auburn, ME metro's median AQI rose from 31 to 34 between the 2024 and 2025 EPA annual releases, a change of +3 points.

Compared against 366 monitored days in 2024 and 363 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

Lewiston-Auburn, ME sits in the upper Good-day tercile among EPA CBSA metros on this site (85.2% of 365 monitored days). Signature read: 85.2% 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 34 over 365 measured days in 2025 (Good / Good). The monitored-day split lands at 311 Good (85%), 52 Moderate (14%), and 2 Unhealthy-for-Sensitive-Groups (1%). The 90th-percentile AQI finished at 54; the highest single-day reading hit 112 (USG).

Across 2020–2025, Good-day share shifted -5.2 points and median AQI moved +0 (worsening). No Unhealthy-tier days appear in this annual dataset. Metros with comparable AQI profiles include Arkadelphia, AR (96.7% good, AQI 34); Augusta-Waterville, ME (85.2% good, AQI 34); Beatrice, NE (75.8% good, AQI 34).

Best and worst city air quality →

Air Quality Summary

Median AQI

34

Good

Good Days

85.2%

311 of 365 days

Max AQI

112

USG

Health Grade

Good

90th pct: 54

AQI Day Breakdown (2025)

Distribution of 365 monitored days across EPA AQI categories.

Good

311

85%

Moderate

52

14%

USG

2

1%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Good

The Lewiston-Auburn, ME metro area's air quality is rated Good based on 85.2% 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 Lewiston-Auburn, ME metro compare?

How Lewiston-Auburn, ME compares

Good-day share better than typical
Lewiston-Auburn, ME 85.2%
Arkadelphia, AR 96.7%
Typical US metro 70.6%
Median AQI better than typical
Lewiston-Auburn, ME 34
Arkadelphia, AR 34
Typical US metro 41
Unhealthy days / yr better than typical
Lewiston-Auburn, ME 0
Arkadelphia, AR 0
Typical US metro 1

5-Year Air Quality Trend

Air quality is worsening in the Lewiston-Auburn, ME metro. Highest Good-day share: 2024 (92.6%, 339 of 366 monitored days).

Year Good Moderate Unhealthy Median AQI
2020 327 33 0 34
2021 303 53 0 36
2022 327 31 0 32
2023 296 63 0 35
2024 339 27 0 31
2025 311 52 0 34

Metros with a similar median AQI

CBSA peers nationwide whose annual median AQI sits near Lewiston-Auburn, ME (34).

Arkadelphia, AR

Median AQI 34 · 96.7% Good-day share

34

Augusta-Waterville, ME

Median AQI 34 · 85.2% Good-day share

34

Beatrice, NE

Median AQI 34 · 75.8% Good-day share

34

Dyersburg, TN

Median AQI 34 · 76.9% Good-day share

34

Erie, PA

Median AQI 34 · 76.7% Good-day share

34

Grand Island, NE

Median AQI 34 · 82.5% Good-day share

34

Metros with similar unhealthy-day exposure

A second relationship type: metros whose unhealthy-or-worse day count is closest to Lewiston-Auburn, ME'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 Lewiston-Auburn, ME have? ▼
In 2025, the Lewiston-Auburn, ME metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 112.
What is the air quality in the Lewiston-Auburn, ME metro area? ▼
The Lewiston-Auburn, ME metro area has a median Air Quality Index (AQI) of 34, rated "Good." 85.2% of monitored days (311 out of 365) had good air quality in 2025.
Is air quality in Lewiston-Auburn, ME getting better or worse? ▼
Air quality in the Lewiston-Auburn, ME metro is worsening across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2024 at 92.6% (339 of 366 days). Lowest qualifying Good-day share: 2023 at 82.5% (296 of 359 days).
What does AQI 34 mean for health? ▼
An AQI of 34 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 Lewiston-Auburn, ME compare to other metro areas? ▼
The Lewiston-Auburn, ME metro has 85.2% good air days. Similar metros: Arkadelphia, AR (96.7% good), Augusta-Waterville, ME (85.2% good), Beatrice, NE (75.8% good).
What is the 90th percentile AQI for Lewiston-Auburn, ME? ▼
The 90th percentile AQI for the Lewiston-Auburn, ME metro area is 54, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 112 (USG).

Data Sources

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