Washington, DC Air Quality & Smog

Dominant pollutants, when smog is worst, notable historical episodes, and local agency resources for Washington, DC — 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 (urban + occasional wildfire smoke transport).

Seasonal pattern: when smog is worst

Mid-Atlantic ozone season runs roughly May-September. Stagnant hot summer days with high humidity push 8-hour ozone above the 70 ppb standard. PM2.5 spiked dramatically during the June 2023 Canadian wildfire smoke event.

A recent or notable event

June 8, 2023 — DC briefly crossed AQI 250 from Canadian wildfire smoke, prompting outdoor activity advisories across the federal government and DC schools.

Local agencies and resources

The metro spans three jurisdictions; DOEE, MDE, and Virginia DEQ each run portions of the monitor network feeding AirNow.

• DC Department of Energy and Environment (DOEE)
• Maryland Department of the Environment (MDE)
• Virginia DEQ

How to check air quality in Washington, DC

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

Common questions about Washington, DC air quality

Why does Washington, DC have air-quality and smog problems?

Mid-Atlantic ozone season runs roughly May-September. Stagnant hot summer days with high humidity push 8-hour ozone above the 70 ppb standard. PM2.5 spiked dramatically during the June 2023 Canadian wildfire smoke event.

What are the main air pollutants in Washington, DC?

Washington, DC's dominant pollutants are ozone (summer), PM2.5 (urban + occasional wildfire smoke transport). The AQI on any given day is usually driven by whichever of these is highest.

Has Washington, DC had a major air-quality or smog event?

June 8, 2023 — DC briefly crossed AQI 250 from Canadian wildfire smoke, prompting outdoor activity advisories across the federal government and DC schools.

How can I check Washington, DC'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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