State air quality · 2025

District of Columbia Air Quality Ranking

Across 1 monitored counties, the typical county in District of Columbia posts a median AQI of 45 (Good) and 66.0% of monitored days were rated Good, from EPA AQS.

45
Avg median AQI
66.0%
Good-air days
1
Counties monitored
8%
Cleaner than US states

District of Columbia's typical county median AQI is 45 (Good) across 1 monitored counties

According to the U.S. EPA Air Quality System, District of Columbia monitors 1 counties with a day-weighted Good-day share of 66.0%. Cleanest: District of Columbia County (66.0% Good). Most polluted: District of Columbia County (66.0%). These are annual summaries, not live AirNow readings.

Data source EPA Air Quality System (AQS)

Cleaner than US states
District of Columbia's day-weighted Good-day share of 66.0% places it cleaner than 8% of US states.
In-state spread
Within District of Columbia, District of Columbia County leads at 66.0% Good days while District of Columbia County sits at 66.0% across 1 monitored counties.
2024→2025 release
District of Columbia's Good-day share moved +2.4 points vs the 2024 EPA annual release.
Typical median AQI
Typical median AQI: 45

Verify with AirNow → · EPA AQS →

EPA state monitoring brief

AQS state key DISTRICT-OF-COLUMBIA

District of Columbia · 2025 EPA AQS · 1 counties · med AQI 45 · 66.0% Good · District of Columbia→District of Columbia spread

  • GOOD 45 Median AQI · Good
  • SHARE 66.0% Good-day share
  • COUNT 1 Counties monitored
  • UNH 2 Unhealthy+ days
  • RANK 8% Cleaner than states
  • O3 49.9% Main pollutant share

Good-day share peers

Iowa66.8%District of Columbia (this)66%Texas65.6%Utah65.4%
Good-day share neighbourhood · nearest ABS peers vs District of Columbia

District of Columbia's 66.0% Good-day share is cleaner than 8% of monitored US states; District of Columbia and District of Columbia County bracket the in-state range. Open District of Columbia County →

According to EPA AQS annual summaries on PlainAirData, District of Columbia ranks #47 of 52 by day-weighted good-day share (66.0%) and #51 by mean county median AQI (45.0). Hawaii is #1 of 52 by day-weighted good-day share (93.8% of monitored days) at mean county median-AQI #4 (27.3) ≠ Alaska #1 lowest mean county median AQI (20.3) at good-day share #8 (84.4%).

Data updated August 2026

What changed, what drives it, and how thick is the sample

Three derived views WPR-style word count does not substitute for: release-over-release movement from county annual rows, the EPA main-pollutant day mix, and how many counties sit below the 100-day ranking floor.

Release change

66.0%

Good-day share in 2025, up 2.4 percentage points vs 2024. County-mean median AQI 45, within half a point of the 2024 county-mean median.

Pollutant mix

Ozone

Main driver on 49.9% of pollutant-assigned days.

  • Ozone 49.9%
  • PM2.5 47.1%
  • NO2 3.0%

Monitoring coverage

365

Average monitored days per county in the latest release. Every monitored county clears the 100-day ranking floor.

Counties Monitored

1

Good Days %

66.0%

Avg Median AQI

45

Total Unhealthy Days

2

Best Air Quality

District of Columbia County

Worst Air Quality

District of Columbia County

Where District of Columbia sits nationally

COUNT-derived placement among 52 US states with at least 365 monitored days in the latest county release. District of Columbia's day-weighted Good-day share is 66.0% - cleaner than 8% of that comparison set.

District of Columbia Good-day share vs. every US state

Day-weighted share of monitored days in the Good band (AQI 0–50) - EPA AQS annual release

66.0% 8th percentile higher than 8% of 52 US states

0.0%–5.0%: 0 US states (0%). Below this entry. 5.0%–10.0%: 0 US states (0%). Below this entry. 10.0%–15.0%: 0 US states (0%). Below this entry. 15.0%–20.0%: 0 US states (0%). Below this entry. 20.0%–25.0%: 0 US states (0%). Below this entry. 25.0%–30.0%: 0 US states (0%). Below this entry. 30.0%–35.0%: 0 US states (0%). Below this entry. 35.0%–40.0%: 0 US states (0%). Below this entry. 40.0%–45.0%: 0 US states (0%). Below this entry. 45.0%–50.0%: 0 US states (0%). Below this entry. 50.0%–55.0%: 0 US states (0%). Below this entry. 55.0%–60.0%: 0 US states (0%). Below this entry. 60.0%–65.0%: 2 US states (4%). Below this entry. 65.0%–70.0%: 9 US states (17%). This entry sits in this band. 70.0%–75.0%: 11 US states (21%). Above this entry. 75.0%–80.0%: 11 US states (21%). Above this entry. 80.0%–85.0%: 13 US states (25%). Above this entry. 85.0%–90.0%: 5 US states (10%). Above this entry. 90.0%–95.0%: 1 US states (2%). Above this entry. 95.0%–100.0%: 0 US states (0%). Above this entry. 100.0%–105.0%: 0 US states (0%). Above this entry. This state 0.0% 100% every floor-qualified US state, bucketed by value

Each bar is a band; taller bars hold more US states. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.

Source U.S. Environmental Protection Agency, Air Quality System (AQS) · 2025

Which counties in District of Columbia have the cleanest and most polluted air?

County Good % Median AQI
District of Columbia 66.0% 45

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025. See our methodology for how AQI and median figures are computed.

Coverage: 1 counties in District of Columbia with active monitoring stations. Unmonitored counties are not represented.

Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files, aggregated to the state level · 2020–2025

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.

Informational only, not professional advice. Data from EPA AQS. See our disclaimer.