District of Columbia · County air quality · 2025

District of Columbia County, District of Columbia

Median AQI 45 (Good). 66.0% of monitored days rated Good, direct from EPA Air Quality System stations.

45
Median AQI
66.0%
Good-air days
2
Unhealthy days
25%
Cleaner than US counties

District of Columbia County's 2025 annual median AQI is 45 (Good), with 66.0% Good days

According to the U.S. EPA Air Quality System, District of Columbia County, District of Columbia posted a 2025 median AQI of 45 (Good) across 365 monitored days, with 66.0% rated Good and 2 unhealthy or worse. This is an annual comparison, not today's advisory.

Data source EPA Air Quality System (AQS)

Cleaner than US
District of Columbia County's 66.0% Good-day share places it cleaner than 25% of US counties in 2025.
Closest median-AQI peer
Baltimore County (64.7% Good, median AQI 45) is the closest nationwide median-AQI peer to District of Columbia County.
2020–2025 trend
District of Columbia County's floor-qualifying Good-day share is stable from 2020 to 2025 (67.8% → 66.0%).
Median AQI
Median AQI: 45

According to the 2025 EPA AQS county release on PlainAirData, District of Columbia County, District of Columbia ranks #750 of 951 by median AQI (45) and #712 by good-day share (66.0%). Ponce County, Puerto Rico is #1 of 951 by median AQI (3, 91.4% Good days) at good-day-share #159 ≠ largest of 7 at 100.0% Good days #1 by good-day share (100.0%, median AQI 9) at median-AQI #7.

Annual release change

What changed in the 2025 EPA annual release

2024 → 2025
  • District of Columbia County's peak single-day AQI rose from 133 to 185 between the 2024 and 2025 EPA annual releases, a change of +52 points.
  • District of Columbia County's Good-day share rose from 63.7% to 66.0% between the 2024 and 2025 EPA annual releases, a change of +2.4 percentage points.
  • District of Columbia County's Unhealthy-category days rose from 0 to 2 between the 2024 and 2025 EPA annual releases, a change of +2 days.

Compared against 366 monitored days in 2024 and 365 in 2025. These are arithmetic differences between two stored EPA annual summaries, not a cause claim or a live advisory.

National release changes Two-year CSV

Data updated August 2026

District of Columbia County AQI category distribution Stacked-segment bar showing the share of monitored days that fell in each EPA AQI category, Good, Moderate, USG, Unhealthy, Very Unhealthy, Hazardous, with median AQI marker. AQI category distribution 365 monitored days G M Median AQI 45 0 50 100 150 200 300 500 District of Columbia County
  • Good · 241 d · 66.0%
  • Moderate · 120 d · 32.9%
  • USG · 2 d · 0.5%
  • Unhealthy · 2 d · 0.5%

How did District of Columbia County's air break down in 2025?

Across 365 monitored days, 241 fell in the Good band (AQI 0–50) and 2 reached Unhealthy or worse. The worst single day peaked at AQI 185 (Unhealthy).

EPA AQS →
District of Columbia County, Good days share 66.0%
National avg

Share of monitored days at AQI 0-50 (Good band).

District of Columbia County, Unhealthy-or-worse share 5.5%
National avg

Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).

Where District of Columbia County sits nationally

COUNT-derived placement among 951 US counties with at least 100 monitored days in 2025. District of Columbia County's Good-day share is 66.0% - cleaner than 25% of that comparison set.

District of Columbia County Good-day share vs. every US county

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

66.0% 25th percentile higher than 25% of 951 US counties

0.0%–5.0%: 0 US counties (0%). Below this entry. 5.0%–10.0%: 1 US counties (0%). Below this entry. 10.0%–15.0%: 4 US counties (0%). Below this entry. 15.0%–20.0%: 4 US counties (0%). Below this entry. 20.0%–25.0%: 1 US counties (0%). Below this entry. 25.0%–30.0%: 5 US counties (1%). Below this entry. 30.0%–35.0%: 9 US counties (1%). Below this entry. 35.0%–40.0%: 4 US counties (0%). Below this entry. 40.0%–45.0%: 16 US counties (2%). Below this entry. 45.0%–50.0%: 16 US counties (2%). Below this entry. 50.0%–55.0%: 32 US counties (3%). Below this entry. 55.0%–60.0%: 50 US counties (5%). Below this entry. 60.0%–65.0%: 77 US counties (8%). Below this entry. 65.0%–70.0%: 93 US counties (10%). This entry sits in this band. 70.0%–75.0%: 109 US counties (11%). Above this entry. 75.0%–80.0%: 114 US counties (12%). Above this entry. 80.0%–85.0%: 123 US counties (13%). Above this entry. 85.0%–90.0%: 99 US counties (10%). Above this entry. 90.0%–95.0%: 117 US counties (12%). Above this entry. 95.0%–100.0%: 70 US counties (7%). Above this entry. 100.0%–105.0%: 7 US counties (1%). Above this entry. This county 0.0% 100% every floor-qualified US county, bucketed by value

Each bar is a band; taller bars hold more US counties. 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

Pollutant Breakdown

Days where each pollutant was the primary driver of AQI readings in District of Columbia County.

District of Columbia County, District of Columbia criteria pollutant distribution Stratified-band visualization showing the share of monitored days each criteria pollutant (PM2.5, PM10, O3, NO2, CO) was the primary AQI driver. Ozone · 49.9% PM2.5 · 47.1% 0% 25% 50% 75% 100% District of Columbia County, District of Columbia · 365 monitored days Criteria pollutant column
  • Ozone · 182 days · 49.9%
  • PM2.5 · 172 days · 47.1%
  • NO₂ · 11 days · 3.0%

Health Impact Assessment

Moderate

District of Columbia County's air quality is rated Moderate based on 66.0% good air days. There were 2 unhealthy days in 2025 when outdoor activity should be limited.

Air quality is acceptable most days, but 2 days reached "Unhealthy for Sensitive Groups" (AQI 101-150) and peak AQI reached 185. Sensitive groups should monitor real-time conditions at AirNow.gov.

The dominant pollutant is Ozone, driving AQI on 182 of 365 monitored days.

5-Year Air Quality Trend

Air quality is stable in District of Columbia County. Highest Good-day share: 2020 (67.8%, 248 of 366 monitored days).

Year Good Moderate USG Unhealthy Median AQI
2020 248 117 0 1 44
2021 172 185 7 1 51
2022 198 163 4 0 49
2023 189 164 9 3 50
2024 233 129 4 0 45
2025 241 120 2 2 45

How does District of Columbia County compare?

How District of Columbia County compares

Good-day share worse than typical
District of Columbia County 66.0%
Baltimore County, Maryland 64.7%
Typical US county 76.0%
Median AQI worse than typical
District of Columbia County 45
Baltimore County, Maryland 45
Typical US county 39
Unhealthy days / yr worse than typical
District of Columbia County 2
Baltimore County, Maryland 0
Typical US county 1

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 District of Columbia County, District of Columbia · 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.