Metro area air quality · 2025

Flagstaff, AZ

Median AQI 48 (Good). 62.5% of monitored days rated Good across this metro's EPA monitoring network.

48
Median AQI
62.5%
Good-air days
0
Unhealthy days
30%
Cleaner than US metros

Aggregated from EPA Air Quality System (2025), 267 monitored days. EPA AQS →

The verdict

The Flagstaff, AZ metro runs good on the EPA scale, more polluted than the median US metro, a median AQI of 48 with 62.5% of 267 monitored days in the Good band.

48
median AQI · Good
62.5%
days rated Good
30%
cleaner than US metros
113
worst single reading

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

Insights: Flagstaff, AZ metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 48 over 267 measured days in 2025, which corresponds to a Good band and a Moderate metro-wide health grade. The monitored-day split lands at 167 Good days (63%), 98 Moderate (37%), and 2 Unhealthy-for-Sensitive-Groups (1%). The 90th-percentile AQI finished at 74 while the highest single-day reading hit 113 (USG). Metro residents averaged roughly 18.8 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, good days shifted by -135 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 Brookings, SD (53.0% good, AQI 48); Charleston-North Charleston, SC (58.2% good, AQI 48); Chattanooga, TN-GA (53.9% good, AQI 48).

Air Quality Summary

Median AQI

48

Good

Good Days

62.5%

167 of 267 days

Max AQI

113

USG

Health Grade

Moderate

90th pct: 74

AQI Day Breakdown (2025)

Distribution of 267 monitored days across EPA AQI categories.

Good

167

63%

Moderate

98

37%

USG

2

1%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Moderate

The Flagstaff, AZ metro area's air quality is rated Moderate based on 62.5% 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 Flagstaff, AZ metro compare?

How Flagstaff, AZ compares

Good-day share worse than US avg
Flagstaff, AZ 62.5%
Brookings, SD 53.0%
US average 71.3%
Median AQI worse than US avg
Flagstaff, AZ 48
Brookings, SD 48
US average 41
Unhealthy days / yr better than US avg
Flagstaff, AZ 0
Brookings, SD 1
US average 1

5-Year Air Quality Trend

Air quality is worsening in the Flagstaff, AZ metro. Best year: 2020 (302 good days).

Year Good Moderate Unhealthy Median AQI
2020 302 64 0 44
2021 265 100 0 46
2022 279 85 0 44
2023 243 118 2 46
2024 250 111 0 46
2025 167 98 0 48

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to Flagstaff, AZ.

Brookings, SD

AQI 48 · 53.0% good

48

Charleston-North Charleston, SC

AQI 48 · 58.2% good

48

Chattanooga, TN-GA

AQI 48 · 53.9% good

48

Columbia, SC

AQI 48 · 57.3% good

48

Corsicana, TX

AQI 48 · 58.1% good

48

Dayton, OH

AQI 48 · 56.2% good

48

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 Flagstaff, AZ metro area? ▼
The Flagstaff, AZ metro area has a median Air Quality Index (AQI) of 48, rated "Good." 62.5% of monitored days (167 out of 267) had good air quality in 2025.
How many unhealthy air days does Flagstaff, AZ have? ▼
In 2025, the Flagstaff, AZ metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 113.
Is air quality in Flagstaff, AZ getting better or worse? ▼
Air quality in the Flagstaff, AZ metro is worsening based on 5-year trends (2020-2025). Best year: 2020 with 302 good days. Worst year: 2025 with 167 good days.
What does AQI 48 mean for health? ▼
An AQI of 48 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 Flagstaff, AZ? ▼
The 90th percentile AQI for the Flagstaff, AZ metro area is 74, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 113 (USG).
How does Flagstaff, AZ compare to other metro areas? ▼
The Flagstaff, AZ metro has 62.5% good air days. Similar metros: Brookings, SD (53.0% good), Charleston-North Charleston, SC (58.2% good), Chattanooga, TN-GA (53.9% 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.