Metro area air quality · 2025

Vallejo-Fairfield, CA

Median AQI 33 (Good). 99.2% of monitored days rated Good across this metro's EPA monitoring network.

Compiled by PlainAirData · August 23, 2026

33
Median AQI: 99.2%
Good-air days: 0
Unhealthy days: 99%
Cleaner than US metros

Vallejo-Fairfield, CA posted a 2025 median AQI of 33 (Good) with 99.2% Good days

According to the U.S. EPA Air Quality System, the Vallejo-Fairfield, CA CBSA recorded a median AQI of 33 across 356 monitored days in 2025, with 99.2% 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 Vallejo-Fairfield, CA CBSA's 99.2% Good-day share places it cleaner than 99% of US metros in 2025.
Closest median-AQI peer: Bangor, ME (84.2% Good, median AQI 33) is the closest nationwide median-AQI peer to Vallejo-Fairfield, CA.
2020–2025 Good-day shift: Vallejo-Fairfield, CA's Good-day share moved +47.8 points from 2020 to 2025 (median AQI -18).
Median AQI: Median AQI: 33

Aggregated from EPA Air Quality System (2025), 356 monitored days. EPA AQS →

The verdict

The Vallejo-Fairfield, CA metro runs good on the EPA scale, among the cleanest 10% of US metros, a median AQI of 33 with 99.2% of 356 monitored days in the Good band.

33
median AQI · Good: 99.2%
days rated Good: 99%
cleaner than US metros: 61
worst single reading

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

Vallejo-Fairfield, CA metro's Good-day share rose from 94.0% to 99.2% between the 2024 and 2025 EPA annual releases, a change of +5.2 percentage points.
Vallejo-Fairfield, CA metro's peak single-day AQI fell from 80 to 61 between the 2024 and 2025 EPA annual releases, a change of -19 points.
Vallejo-Fairfield, CA metro's median AQI fell from 36 to 33 between the 2024 and 2025 EPA annual releases, a change of -3 points.

Insights: Vallejo-Fairfield, CA metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 33 over 356 measured days in 2025, which corresponds to a Good band and a Excellent metro-wide health grade. The monitored-day split lands at 353 Good days (99%), 3 Moderate (1%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 42 while the highest single-day reading hit 61 (Moderate). Metro residents averaged roughly 29.7 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, the share of monitored days rated Good shifted by +47.8 points and the median AQI moved -18 points, which classifies the multi-year trajectory as improving. The metro recorded no Unhealthy-tier days in this annual dataset. Metros with comparable AQI profiles include Bangor, ME (84.2% good, AQI 33); Clarksburg, WV (72.4% good, AQI 33); Grants Pass, OR (68.2% good, AQI 33).

Air Quality Summary

Median AQI

Good

Good Days

99.2%

353 of 356 days

Max AQI

Moderate

Health Grade

Excellent

90th pct: 42

AQI Day Breakdown (2025)

Distribution of 356 monitored days across EPA AQI categories.

Good

353

99%

Moderate

USG

Unhealthy

Very Unhealthy

Hazardous

Health Impact Assessment

Excellent

The Vallejo-Fairfield, CA metro area's air quality is rated Excellent based on 99.2% 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 Vallejo-Fairfield, CA metro compare?

How Vallejo-Fairfield, CA compares

Compare against

Good-day share better than typical

Vallejo-Fairfield, CA 99.2%

Bangor, ME 84.2%

Typical US metro 70.6%

Median AQI better than typical

Vallejo-Fairfield, CA 33

Bangor, ME 33

Typical US metro 41

Unhealthy days / yr better than typical

Vallejo-Fairfield, CA 0

Bangor, ME 1

Typical US metro 1

5-Year Air Quality Trend

Air quality is improving in the Vallejo-Fairfield, CA metro. Highest Good-day share: 2025 (99.2%, 353 of 356 monitored days).

Year	Good	Moderate	Unhealthy	Median AQI	Max AQI
2020	183	167	6	51	228
2021	215	147	0	44	126
2022	235	130	0	43	93
2023	269	95	0	40	105
2024	343	22	0	36	80
2025	353	3	0	33	61

Metros with a similar median AQI

CBSA peers nationwide whose annual median AQI sits near Vallejo-Fairfield, CA (33).

Bangor, ME

Median AQI 33 · 84.2% Good-day share

Clarksburg, WV

Median AQI 33 · 72.4% Good-day share

Grants Pass, OR

Median AQI 33 · 68.2% Good-day share

Lawrenceburg, TN

Median AQI 33 · 81.5% Good-day share

Roanoke Rapids, NC

Median AQI 33 · 78.1% Good-day share

Rockland, ME

Median AQI 33 · 97.8% Good-day share

Metros with similar unhealthy-day exposure

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

Aberdeen, SD

0 unhealthy-or-worse days · median AQI 27

Aberdeen, WA

0 unhealthy-or-worse days · median AQI 22

Adrian, MI

0 unhealthy-or-worse days · median AQI 41

Akron, OH

0 unhealthy-or-worse days · median AQI 45

Albany, GA

0 unhealthy-or-worse days · median AQI 46

Albany, OR

0 unhealthy-or-worse days · median AQI 27

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 Vallejo-Fairfield, CA metro area? ▼

The Vallejo-Fairfield, CA metro area has a median Air Quality Index (AQI) of 33, rated "Good." 99.2% of monitored days (353 out of 356) had good air quality in 2025.

How many unhealthy air days does Vallejo-Fairfield, CA have? ▼

In 2025, the Vallejo-Fairfield, CA metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 61.

Is air quality in Vallejo-Fairfield, CA getting better or worse? ▼

Air quality in the Vallejo-Fairfield, CA 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 99.2% (353 of 356 days). Lowest qualifying Good-day share: 2020 at 51.4% (183 of 356 days).

What does AQI 33 mean for health? ▼

An AQI of 33 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 Vallejo-Fairfield, CA? ▼

The 90th percentile AQI for the Vallejo-Fairfield, CA metro area is 42, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 61 (Moderate).

How does Vallejo-Fairfield, CA compare to other metro areas? ▼

The Vallejo-Fairfield, CA metro has 99.2% good air days. Similar metros: Bangor, ME (84.2% good), Clarksburg, WV (72.4% good), Grants Pass, OR (68.2% 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 Accessed 2026-07-06

Send the source-year summary or download its ready-to-use data card.

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Every figure on PlainAirData 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.