Median AQI
61
Moderate
California · County air quality · 2025
Fresno County, California
Median AQI 61 (Moderate). 28.8% of monitored days rated Good, direct from EPA Air Quality System stations.
- 61
- Median AQI
- 28.8%
- Good-air days
- 3
- Unhealthy days
- 1%
- Cleaner than US counties
Fresno County's 2025 annual median AQI is 61 (Moderate), with 28.8% Good days
According to the U.S. EPA Air Quality System, Fresno County, California posted a 2025 median AQI of 61 (Moderate) across 365 monitored days, with 28.8% rated Good and 3 unhealthy or worse. This is an annual comparison, not today's advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US
- Fresno County's 28.8% Good-day share places it cleaner than 1% of US counties in 2025.
- Closest median-AQI peer
- Clark County (31.0% Good, median AQI 61) is the closest nationwide median-AQI peer to Fresno County.
- 2020–2025 trend
- Fresno County's floor-qualifying Good-day share is improving from 2020 to 2025 (21.0% → 28.8%).
- Median AQI
- Median AQI: 61
The verdict
According to EPA Air Quality System monitoring data, Fresno County's air is moderate on balance, among the most polluted counties nationally, a median AQI of 61 with 28.8% of 365 monitored days in the Good band, driven mainly by Ozone.
- 61
- median AQI · Moderate
- 28.8%
- days rated Good
- Ozone
- main pollutant
- 1%
- cleaner than US counties
3 days reached Unhealthy or worse; the worst single reading hit AQI 164.
Annual release change
What changed in the 2025 EPA annual release
- Fresno County's Unhealthy-category days fell from 14 to 3 between the 2024 and 2025 EPA annual releases, a change of -11 days.
- Fresno County's Good-day share rose from 19.4% to 28.8% between the 2024 and 2025 EPA annual releases, a change of +9.4 percentage points.
- Fresno County's median AQI fell from 67 to 61 between the 2024 and 2025 EPA annual releases, a change of -6 points.
Data updated August 2026
- Good · 105 d · 28.8%
- Moderate · 226 d · 61.9%
- USG · 31 d · 8.5%
- Unhealthy · 3 d · 0.8%
How did Fresno County's air break down in 2025?
Across 365 monitored days, 105 fell in the Good band (AQI 0–50) and 3 reached Unhealthy or worse. The worst single day peaked at AQI 164 (Unhealthy).
EPA AQS →Air quality data from EPA Air Quality System (2025). 365 days monitored. Median AQI: 61 (Moderate).
Insights: Fresno County, California. EPA monitors recorded a median Air Quality Index of 61 across 365 measured days in 2025, earning a Moderate classification and a Poor health grade. Of those days, 105 (29%) fell in the Good band (AQI 0–50), 226 (62%) registered Moderate readings, and 31 (8%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 100, while the worst single-day peak hit 164 (Unhealthy). Residents averaged about 8.6 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (204 days), PM2.5 (151 days), PM10 (10 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by +8.3 points and the median AQI moved -15 points, placing the multi-year trajectory at improving. The annual record contains 3 days at Unhealthy or worse. On those days, the EPA recommends that sensitive groups limit prolonged outdoor exertion. Nearby counties show comparable readings: Alameda (53.0% good, AQI 49); Amador (87.4% good, AQI 38); Butte (65.2% good, AQI 46); Calaveras (82.2% good, AQI 40); Colusa (79.2% good, AQI 40); Contra Costa (53.5% good, AQI 48).
Air Quality Summary
Good Days
28.8%
105 of 365 monitored days
-46.2pp vs 75% target
Max AQI Recorded
164
Unhealthy
Health Grade
Poor
90th-pct AQI 100
Fresno County, Good days share 28.8%
National avg
Share of monitored days at AQI 0-50 (Good band).
Fresno County, Unhealthy-or-worse share 8.2%
National avg
Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).
AQI Day Breakdown (2025)
Distribution of 365 monitored days across EPA AQI categories.
Good
105
29%
Moderate
226
62%
USG
31
8%
Unhealthy
3
1%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Fresno County.
- Ozone · 204 days · 55.9%
- PM2.5 · 151 days · 41.4%
- PM10 · 10 days · 2.7%
Health Impact Assessment
Poor
Fresno County's air quality is rated Poor based on 28.8% good air days. There were 3 unhealthy days in 2025 when outdoor activity should be limited.
Air quality is acceptable most days, but 31 days reached "Unhealthy for Sensitive Groups" (AQI 101-150) and peak AQI reached 164. Sensitive groups should monitor real-time conditions at AirNow.gov.
The dominant pollutant is Ozone, driving AQI on 204 of 365 monitored days.
5-Year Air Quality Trend
Air quality is improving in Fresno County. Highest Good-day share: 2025 (28.8%, 105 of 365 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 75 | 192 | 59 | 31 | 76 | 346 |
| 2021 | 62 | 221 | 63 | 17 | 68 | 278 |
| 2022 | 78 | 217 | 67 | 3 | 71 | 159 |
| 2023 | 97 | 210 | 55 | 3 | 64 | 156 |
| 2024 | 71 | 216 | 65 | 14 | 67 | 169 |
| 2025 | 105 | 226 | 31 | 3 | 61 | 164 |
How does Fresno County compare?
How Fresno County compares
Good-day share worse than typical
Fresno County 28.8%
Clark County, Nevada 31.0%
Typical US county 76.0%
Median AQI worse than typical
Fresno County 61
Clark County, Nevada 61
Typical US county 39
Unhealthy days / yr worse than typical
Fresno County 3
Clark County, Nevada 0
Typical US county 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Fresno County (61), not geographic neighbors.
Clark County, Nevada
Median AQI 61 · 31.0% Good-day share
Dona Ana County, New Mexico
Median AQI 61 · 27.4% Good-day share
Harris County, Texas
Median AQI 62 · 11.0% Good-day share
Bernalillo County, New Mexico
Median AQI 58 · 26.6% Good-day share
Imperial County, California
Median AQI 64 · 27.7% Good-day share
Tulare County, California
Median AQI 64 · 24.1% Good-day share
Same primary pollutant: Ozone
Ozone led the AQI on the most monitored days here. These peers share that driver and the closest Good-day share (a second relationship type beyond median-AQI neighbors).
Salt Lake County, Utah
33.1% Good-day share · median AQI 57
Pima County, Arizona
33.7% Good-day share · median AQI 54
Inyo County, California
37.3% Good-day share · median AQI 55
Kern County, California
17.5% Good-day share · median AQI 70
Weld County, Colorado
44.7% Good-day share · median AQI 52
San Bernardino County, California
12.6% Good-day share · median AQI 77
California counties on the map
Geographic containment only, other monitored counties in California, independent of AQI or pollutant match.
What Fresno County's air means for you
On most days the air here is fine, but Ozone drives 3 unhealthy-or-worse days a year that sensitive groups should plan around.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-Ozone days, the guide explains what a median of 61 means for exposure. Health guidance
- See how Fresno County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Fresno County with its California neighbours before drawing a conclusion about the region. All of California
Based on 365 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
Keep exploring the annual AQI record
Air-quality reading list
Frequently Asked Questions
What is the air quality in Fresno County, California? ▼
Fresno County has a median Air Quality Index (AQI) of 61, rated "Moderate." 28.8% of monitored days (105 out of 365) had good air quality in 2025.
What is the main pollutant in Fresno County? ▼
The primary pollutant in Fresno County is Ozone (O3), which was the main AQI driver on 204 days (56% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Fresno County have? ▼
In 2025, Fresno County recorded 3 unhealthy air days (3 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 164.
Is the air quality in Fresno County getting better or worse? ▼
Air quality in Fresno County 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 28.8% (105 of 365 days). Lowest qualifying Good-day share: 2021 at 17.1% (62 of 365 days).
What does AQI 61 mean for health? ▼
Fresno County's median AQI of 61 falls in the "Moderate" category. See the AQI category guide for what each range means for health.
How does Fresno County compare to other counties in California? ▼
Fresno County has 28.8% good air days. Nearby counties in California: Alameda (53.0% good), Amador (87.4% good), Butte (65.2% good), Calaveras (82.2% good), Colusa (79.2% good), Contra Costa (53.5% good).
What is the 90th percentile AQI in Fresno County? ▼
The 90th percentile AQI for Fresno County is 100, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 164 (Unhealthy).
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025 (aqs.epa.gov). For current conditions (not shown here — this page is historical annual data), see EPA AirNow (airnow.gov). See our methodology for how AQI, median, and coverage figures are computed.
Informational only, not professional advice. Data from EPA AQS. See our disclaimer. Spotted a figure that looks wrong? Report a correction.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files for Fresno County, California · 2020–2025
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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.