Washington Air Quality in 2020
In 2020, Washington's air quality (Washington-Arlington-Alexandria, DC-VA-MD-WV area) had a median daily AQI of 47 (Good) across 366 monitored days. 3 days (0.8%) reached Unhealthy for Sensitive Groups or worse, 214 were Good, and the year's peak AQI was 171 (Unhealthy). Fine particulate matter (PM2.5) set the daily AQI on 226 of those days. The cleanest month of 2020 was January (median AQI 39, 0 days above 100) and the worst was July (median 57, 3 days above 100, peak 171).
- Good: 58.5%
- Moderate: 40.7%
- Unhealthy for Sensitive Groups: 0.5%
- Unhealthy or worse: 0.3%
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How was Washington's air quality in 2020?
Good on a typical day: median AQI 47, with 3 days above AQI 100 out of 366 monitored — the 1st cleanest of 7 years on record for the area.
- ✓Peak AQI in 2020: 171 (Unhealthy).
- ✓Fine particulate matter (PM2.5) was the main pollutant on 226 days.
- ✓Cleanest month: January; worst: July.
Frequently asked questions
What was the average AQI in Washington in 2020?▾
EPA's Air Quality System puts Washington's (Washington-Arlington-Alexandria, DC-VA-MD-WV) median daily AQI for 2020 at 47, which is Good. 3 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 171.
Which month had the worst air quality in Washington in 2020?▾
The cleanest month of 2020 was January (median AQI 39, 0 days above 100) and the worst was July (median 57, 3 days above 100, peak 171).
Was 2020 a good or bad year for Washington's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2020 ranks 1st cleanest by days above AQI 100 — the best year on record here. 2020's median of 47 is below the area's typical annual median of 52.
Washington month by month in 2020
Washington air quality month by month, 2020 (Washington-Arlington-Alexandria, DC-VA-MD-WV, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| Januarycleanest | 31 | 39 | 0 | 70 | PM2.5 |
| February | 29 | 43 | 0 | 67 | PM2.5 |
| March | 31 | 43 | 0 | 61 | PM2.5 |
| April | 30 | 45 | 0 | 62 | O3 |
| May | 31 | 45 | 0 | 58 | O3 |
| June | 30 | 53 | 0 | 92 | PM2.5 |
| Julyworst | 31 | 57 | 3 | 171 | O3 |
| August | 31 | 51 | 0 | 71 | PM2.5 |
| September | 30 | 46 | 0 | 58 | PM2.5 |
| October | 31 | 43 | 0 | 64 | PM2.5 |
| November | 30 | 53 | 0 | 90 | PM2.5 |
| December | 31 | 46 | 0 | 83 | PM2.5 |
How 2020 compares
Among the 7 years EPA has published for the area (2019–2025), 2020 ranks 1st cleanest by days above AQI 100 — the best year on record here.
2020's median of 47 is below 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.