Air quality
Air quality in Rockville today
Updated
Moderate (US AQI 66) Acceptable for most people. Unusually sensitive people should consider shortening long or heavy exertion outdoors. Model estimate for Sun, Oct 25, 9:00 pm (01:00 UTC).
Live AQI, PM2.5, PM10 and ozone for Rockville, Maryland, United States, with a 48-hour forecast and the best time to be outside.
- US AQI now
- 66 Moderate
- PM2.5
- 34 µg/m³ 2.2× WHO 24-h guideline
- PM10
- 37 µg/m³
- Ozone
- 8 µg/m³
- Dominant pollutant
- PM2.5 sub-index 66
- Best hour tomorrow
- 9:00 pm AQI 74
- European AQI
- 66
Air quality in Rockville right now
Right now the modelled US Air Quality Index for Rockville, Maryland, United States is 66, which falls in the "Moderate" band (up to 100). Acceptable for most people. Unusually sensitive people should consider shortening long or heavy exertion outdoors.
The index is driven mainly by PM2.5, whose own sub-index is 66. Fine and coarse particles come from traffic, heating, industry, dust and smoke; they build up on calm nights and clear when wind or rain arrives.
PM2.5 is 34 µg/m³, 2.2 times the WHO 24-hour guideline of 15 µg/m³; PM10 is 37 µg/m³ against a guideline of 45; ozone is 8 µg/m³ (below the WHO 8-hour level of 100); nitrogen dioxide is 72 µg/m³ (above the 24-hour guideline of 25).
Also this hour: carbon monoxide 519 µg/m³.
Rockville AQI forecast: next 48 hours
Over the next 24 hours the AQI is forecast to range from 66 around Sun 9:00 pm to 78 around Mon 9:00 am, staying "Moderate" throughout.
The following day is expected to be cleaner, averaging about 59 against 75 for the next 24 hours.
| Local time (America/New_York) | US AQI | Category | PM2.5 µg/m³ | PM10 µg/m³ | Ozone µg/m³ |
|---|---|---|---|---|---|
| Sun 9:00 pm | 66 | Moderate | 33.6 | 37 | 8 |
| Mon 12:00 am | 70 | Moderate | 37.8 | 41 | 7 |
| Mon 3:00 am | 74 | Moderate | 35 | 39 | 9 |
| Mon 6:00 am | 77 | Moderate | 27.4 | 31 | 13 |
| Mon 9:00 am | 78 | Moderate | 21.2 | 24 | 26 |
| Mon 12:00 pm | 78 | Moderate | 9.2 | 11 | 76 |
| Mon 3:00 pm | 78 | Moderate | 5.8 | 6 | 114 |
| Mon 6:00 pm | 76 | Moderate | 8.6 | 9 | 90 |
| Mon 9:00 pm | 74 | Moderate | 15.7 | 16 | 42 |
| Tue 12:00 am | 69 | Moderate | 11.3 | 12 | 60 |
| Tue 3:00 am | 63 | Moderate | 11.3 | 12 | 73 |
| Tue 6:00 am | 58 | Moderate | 12.3 | 12 | 64 |
| Tue 9:00 am | 55 | Moderate | 16 | 16 | 49 |
| Tue 12:00 pm | 54 | Moderate | 5.5 | 6 | 62 |
| Tue 3:00 pm | 53 | Moderate | 5.2 | 5 | 82 |
| Tue 6:00 pm | 53 | Moderate | 7.8 | 8 | 63 |
| Tue 9:00 pm | 53 | Moderate | 15.4 | 16 | 11 |
Every third hour of the CAMS forecast via Open-Meteo. US AQI uses rolling averages (24 h for particles, 8 h for ozone), so it moves more slowly than the hourly concentrations.
Best time to be outside in Rockville tomorrow
Between 6 am and 9 pm local time, the cleanest air tomorrow is forecast around 9:00 pm (AQI 74, Moderate) and the worst around 9:00 am (AQI 78). The difference across the day is small, so timing matters little.
Rockville vs the rest of United States
Across 619 United States cities we track, the average US AQI right now is 53 (Moderate). Rockville at 66 is 13 points worse than average.
For context, the median across 3,556 cities worldwide is 58.
Air quality in cities near Rockville
| City | Distance | US AQI | Category | PM2.5 µg/m³ |
|---|---|---|---|---|
| Potomac | 9 km | 71 | Moderate | 38 |
| Arlington, VA | 23 km | 70 | Moderate | 39.5 |
| Washington | 23 km | 70 | Moderate | 39.5 |
| Columbia, MD | 32 km | 70 | Moderate | 32.4 |
| Alexandria, VA | 32 km | 70 | Moderate | 39.5 |
| Frederick | 43 km | 65 | Moderate | 18.2 |
Model vs measured
We found no measured PM2.5 sensor cell within 25 km of Rockville, so the numbers on this page are model estimates. Models capture regional pollution well but can miss very local sources such as a busy road or a nearby fire.
Wildfire smoke
PM2.5 is forecast to reach 38 µg/m³ in the next 24 hours while NASA satellites detected 32 fire hotspots within 300 km in the last day (nearest about 80 km away). Smoke is a likely contributor: keep windows closed, run an air purifier or HVAC filter, and check the fire map before heading out.
Advice for sensitive groups
At 66, most people are fine outdoors. If you are unusually sensitive to PM2.5, keep long or intense workouts to the cleaner hours shown above.
What the US AQI numbers mean
| US AQI | Category | What it means |
|---|---|---|
| 0-50 | Good | Air quality is satisfactory and poses little or no risk; a good time for outdoor activity. |
| 51-100 | Moderate | Acceptable for most people. Unusually sensitive people should consider shortening long or heavy exertion outdoors. |
| 101-150 | Unhealthy for Sensitive Groups | People with heart or lung disease, older adults, children and teens should cut back on prolonged or heavy exertion outdoors. |
| 151-200 | Unhealthy | Everyone should reduce prolonged or heavy exertion outdoors; sensitive groups should avoid it and keep windows closed. |
| 201-300 | Very Unhealthy | Health alert: everyone should avoid prolonged or heavy exertion outdoors, and sensitive groups should stay indoors. |
| 301-500 | Hazardous | Emergency conditions: everyone should avoid all outdoor physical activity and stay indoors with filtered air if possible. The scale tops out at 500; heavier dust or smoke is shown as 500. |
Values on this page are modelled by CAMS (Copernicus) and served by Open-Meteo; they are estimates for the area around the city centre, not readings from an official monitor.
Nearby cities
More for Rockville
Air quality elsewhere
Data: Open-Meteo Air Quality API, Copernicus Atmosphere Monitoring Service (CAMS), NASA FIRMS.