Metro area air quality · 2024

Vallejo-Fairfield, CA

Median AQI 36 (Good). 94.0% of monitored days rated Good across this metro's EPA monitoring network.

36
Median AQI
94.0%
Good-air days
0
Unhealthy days
92%
Cleaner than US metros

Aggregated from EPA Air Quality System (2024), 365 monitored days. EPA AQS → · NOAA →

Insights: Vallejo-Fairfield, CA metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 36 over 365 measured days in 2024, which corresponds to a Good band and a Excellent metro-wide health grade. The monitored-day split lands at 343 Good days (94%), 22 Moderate (6%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 46 while the highest single-day reading hit 80 (Moderate). Metro residents averaged roughly 28.2 clean-air days per 30-day window across the reporting year.

Across the 2020–2024 trend window, good days shifted by +160 and the median AQI moved -15 points, which classifies the multi-year trajectory as improving. 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 Barnstable Town, MA (94.3% good, AQI 36); Bemidji, MN (84.2% good, AQI 36); Bennington, VT (91.0% good, AQI 36).

Air Quality Summary

Median AQI

36

Good

Good Days

94.0%

343 of 365 days

Max AQI

80

Moderate

Health Grade

Excellent

90th pct: 46

AQI Day Breakdown (2024)

Distribution of 365 monitored days across EPA AQI categories.

Good

343

94%

Moderate

22

6%

USG

0

0%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Excellent

The Vallejo-Fairfield, CA metro area's air quality is rated Excellent based on 94.0% good air days. No unhealthy air days were recorded in 2024.

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

Good-day share better than US avg
Vallejo-Fairfield, CA 94.0%
Barnstable Town, MA 94.3%
US average 70.2%
Median AQI better than US avg
Vallejo-Fairfield, CA 36
Barnstable Town, MA 36
US average 41
Unhealthy days / yr better than US avg
Vallejo-Fairfield, CA 0
Barnstable Town, MA 0
US average 1

5-Year Air Quality Trend

Air quality is improving in the Vallejo-Fairfield, CA metro. Best year: 2024 (343 good days).

Year Good Moderate Unhealthy Median AQI
2020 183 167 6 51
2021 215 147 0 44
2022 235 130 0 43
2023 269 95 0 40
2024 343 22 0 36

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to Vallejo-Fairfield, CA.

Barnstable Town, MA

AQI 36 · 94.3% good

36

Bemidji, MN

AQI 36 · 84.2% good

36

Bennington, VT

AQI 36 · 91.0% good

36

Brookings, SD

AQI 36 · 79.8% good

36

Cadillac, MI

AQI 36 · 89.1% good

36

Crestview-Fort Walton Beach-Destin, FL

AQI 36 · 93.2% good

36

More Air Quality Data

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Worst Air Quality

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All Metro Areas

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Air Quality Guides

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Understanding AQI

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Best & Worst City Air Quality

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Health Effects of Air Pollution

How PM2.5 and ozone exposure affects respiratory and cardiovascular health.

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 36, rated "Good." 94.0% of monitored days (343 out of 365) had good air quality in 2024.
How many unhealthy air days does Vallejo-Fairfield, CA have? ▼
In 2024, the Vallejo-Fairfield, CA metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 80.
Is air quality in Vallejo-Fairfield, CA getting better or worse? ▼
Air quality in the Vallejo-Fairfield, CA metro is improving based on 5-year trends (2020-2024). Best year: 2024 with 343 good days. Worst year: 2020 with 183 good days.
What does AQI 36 mean for health? ▼
An AQI of 36 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 46, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 80 (Moderate).
How does Vallejo-Fairfield, CA compare to other metro areas? ▼
The Vallejo-Fairfield, CA metro has 94.0% good air days. Similar metros: Barnstable Town, MA (94.3% good), Bemidji, MN (84.2% good), Bennington, VT (91.0% good).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset, 2020–2024. The AQS collects ambient air monitoring data from state, local, and tribal monitoring agencies across the United States.

Metrics: Air Quality Index (AQI) is calculated using EPA-standard breakpoints for six criteria pollutants: PM2.5, PM10, Ozone, NO2, CO, and SO2. Median AQI, max AQI, and 90th percentile AQI are computed from daily measurements. Good days percentage reflects days with AQI 0–50.

Coverage: 501 metro areas (Core Based Statistical Areas). Only metros with active monitoring stations are included. Unmonitored areas are not represented.

Read our methodology , how this data is sourced, computed, and verified.

Source: U.S. EPA, AirNow / AQS Air Quality Index readings and pollutant concentrations · 2025