Houston, TX Air Quality & Smog

Dominant pollutants, when smog is worst, notable historical episodes, and local agency resources for Houston, TX — 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

ozone (summer), PM2.5 (industrial + transport), HRVOCs (highly reactive VOCs from petrochemical plants).

Seasonal pattern: when smog is worst

Houston combines an enormous petrochemical complex (the largest in the US) with hot, humid, stagnant summer weather. The Ship Channel corridor produces both ozone precursors and direct industrial emissions. Houston has been in ozone nonattainment since the 1990 Clean Air Act amendments.

A recent or notable event

The 2019 ITC Deer Park tank-farm fire produced visible plumes for days, prompting shelter-in-place orders across multiple Harris County school districts.

Local agencies and resources

TCEQ runs the AirNow monitors. Harris County operates a more-detailed local monitor network around the Ship Channel.

• Texas Commission on Environmental Quality (TCEQ)
• Harris County Pollution Control Services

How to check air quality in Houston

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

Common questions about Houston air quality

Why does Houston have air-quality and smog problems?

Houston combines an enormous petrochemical complex (the largest in the US) with hot, humid, stagnant summer weather. The Ship Channel corridor produces both ozone precursors and direct industrial emissions. Houston has been in ozone nonattainment since the 1990 Clean Air Act amendments.

What are the main air pollutants in Houston?

Houston's dominant pollutants are ozone (summer), PM2.5 (industrial + transport), HRVOCs (highly reactive VOCs from petrochemical plants). The AQI on any given day is usually driven by whichever of these is highest.

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

The 2019 ITC Deer Park tank-farm fire produced visible plumes for days, prompting shelter-in-place orders across multiple Harris County school districts.

How can I check Houston'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.

Related