Washington Air Quality in 2019
In 2019, Washington's air quality (Washington-Arlington-Alexandria, DC-VA-MD-WV area) had a median daily AQI of 52 (Moderate) across 365 monitored days. 11 days (3.0%) reached Unhealthy for Sensitive Groups or worse, 161 were Good, and the year's peak AQI was 159 (Unhealthy). Fine particulate matter (PM2.5) set the daily AQI on 194 of those days. The cleanest month of 2019 was October (median AQI 42, 0 days above 100) and the worst was July (median 64, 4 days above 100, peak 159).
- Good: 44.1%
- Moderate: 52.9%
- Unhealthy for Sensitive Groups: 2.7%
- Unhealthy or worse: 0.3%
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How was Washington's air quality in 2019?
Moderate on a typical day: median AQI 52, with 11 days above AQI 100 out of 365 monitored — the 6th cleanest of 7 years on record for the area.
- ✓Peak AQI in 2019: 159 (Unhealthy).
- ✓Fine particulate matter (PM2.5) was the main pollutant on 194 days.
- ✓Cleanest month: October; worst: July.
Frequently asked questions
What was the average AQI in Washington in 2019?▾
EPA's Air Quality System puts Washington's (Washington-Arlington-Alexandria, DC-VA-MD-WV) median daily AQI for 2019 at 52, which is Moderate. 11 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 159.
Which month had the worst air quality in Washington in 2019?▾
The cleanest month of 2019 was October (median AQI 42, 0 days above 100) and the worst was July (median 64, 4 days above 100, peak 159).
Was 2019 a good or bad year for Washington's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2019 ranks 6th cleanest by days above AQI 100. 2019's median of 52 is in line with the area's typical annual median of 52.
Washington month by month in 2019
Washington air quality month by month, 2019 (Washington-Arlington-Alexandria, DC-VA-MD-WV, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 48 | 0 | 74 | PM2.5 |
| February | 28 | 54 | 0 | 88 | PM2.5 |
| March | 31 | 51 | 0 | 77 | PM2.5 |
| April | 30 | 52 | 0 | 74 | O3 |
| May | 31 | 57 | 0 | 87 | PM2.5 |
| June | 30 | 50 | 3 | 119 | O3 |
| Julyworst | 31 | 64 | 4 | 159 | O3 |
| August | 31 | 59 | 3 | 122 | O3 |
| September | 30 | 55 | 1 | 112 | O3 |
| Octobercleanest | 31 | 42 | 0 | 63 | O3 |
| November | 30 | 51 | 0 | 69 | PM2.5 |
| December | 31 | 47 | 0 | 94 | PM2.5 |
How 2019 compares
Among the 7 years EPA has published for the area (2019–2025), 2019 ranks 6th cleanest by days above AQI 100.
2019's median of 52 is in line with the area's typical annual median of 52.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Washington
The latest EPA AirNow observation puts Washington's AQI at 43 (PM2.5). The figures above are multi-year annual statistics, not today's reading.
View current Washington air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Washington-Arlington-Alexandria, DC-VA-MD-WV), 2019–2025. Daily AQI per CBSA is the highest AQI reported by any monitor in the area that day; the defining parameter is the pollutant that set it. Month and season statistics pool every such day in the period across all years listed. Retrieved 2026-09-09.