Fresno, CA Air Quality & Smog

Dominant pollutants, when smog is worst, notable historical episodes, and local agency resources for Fresno, CA — plus how to check the current AQI. For real-time readings, the free Smog Report iOS app pulls live air quality from EPA AirNow.

Dominant pollutants

PM2.5 (winter — among worst in US), ozone (summer — among worst in US), agricultural emissions.

Seasonal pattern: when smog is worst

Fresno-Madera ranks #2 nationally for both year-round and short-term PM2.5 in the 2025 American Lung Association report — only Bakersfield is worse. Same San Joaquin Valley geometry, same agricultural and traffic mix. Winter Tule fog episodes coincide with the worst PM2.5 days.

A recent or notable event

Fresno County has had EPA "Extreme" ozone nonattainment status — the most-severe possible classification — since 2010.

Local agencies and resources

SJVAPCD runs the densest air-monitor network in the Central Valley.

• SJVAPCD
• CARB

How to check air quality in Fresno

The EPA's AirNow.gov publishes the canonical reading from the nearest regulatory monitor. For glanceable iPhone access — including widgets, Live Activities, Siri voice queries, and Apple Watch — install Smog Report. It's free, requires no account, and pulls from the same AirNow API.

For Fresno-specific advisories and alerts that go beyond the federal AirNow feed, check the agency pages above directly.

Common questions about Fresno air quality

Why does Fresno have air-quality and smog problems?

Fresno-Madera ranks #2 nationally for both year-round and short-term PM2.5 in the 2025 American Lung Association report — only Bakersfield is worse. Same San Joaquin Valley geometry, same agricultural and traffic mix. Winter Tule fog episodes coincide with the worst PM2.5 days.

What are the main air pollutants in Fresno?

Fresno's dominant pollutants are PM2.5 (winter — among worst in US), ozone (summer — among worst in US), agricultural emissions. The AQI on any given day is usually driven by whichever of these is highest.

Has Fresno had a major air-quality or smog event?

Fresno County has had EPA "Extreme" ozone nonattainment status — the most-severe possible classification — since 2010.

How can I check Fresno's air quality right now?

The EPA's AirNow.gov publishes the official reading from the nearest regulatory monitor. For live AQI on your iPhone — with home-screen widgets, Lock Screen Live Activities, Siri, and Apple Watch — the free Smog Report app pulls from the same AirNow feed. No account is required.

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