Is the air in Boston safe today?

Yes. Right now the US AQI in Boston is 29, which counts as good. Great air. A perfect time to be outside. It is expected to reach 59 (moderate) around Fri 6:00 PM.

When is the best time to be outside in Boston?

Sat 9:00 AM–12:00 PM. That is the cleanest stretch in the next 24 hours, with the US AQI averaging about 25. The worst hour is around Fri 6:00 PM, at 59.

What is the main pollutant in Boston?

Ozone (O3). It drives the index right now, at 62 µg/m³. Formed by sunlight acting on traffic and plant emissions. Highest on hot, still afternoons, often downwind of cities.

How does Boston's air compare with the WHO guideline?

Within the guideline. Over the next 24 hours PM2.5 averages about 6.8 µg/m³, against the World Health Organization's 24-hour guideline of 15 µg/m³. The other pollutants stay within their guideline levels.

How many cigarettes is a day of Boston's air?

About 0.3 cigarettes. Over the next 24 hours PM2.5 averages about 6.8 µg/m³. By Berkeley Earth's rule of thumb, 22 µg/m³ breathed for a day is roughly one cigarette.

Will air quality in Boston improve this week?

Sunday looks cleanest. Its AQI peaks at 29, against 59 on Friday, the worst day in the forecast.

Boston air quality

Massachusetts, United States · Live AQI and hourly forecast for the next 5 days · valid Fri 12:00 PM local time

Good

US AQI, mostly O₃

Model estimate. Nearby measurements are shown separately.

Great air. A perfect time to be outside.

Next 24 hours: 21–59US AQI, highest around Fri 6:00 PM
Best time outside: Sat 9:00 AM–12:00 PMUS AQI about 25
PM_2.5 vs WHO guideline: 0.5×6.8 µg/m³ over 24 h, guideline 15
Cigarette equivalent: ≈ 0.3 a dayBerkeley Earth rule of thumb

Loading the live globe…

The live globe, centred on Boston. Switch pollutants, drag through the next 5 days or press play. Full map →

Pollutants in Boston right now

Pollutant	Now	Level	Next 24 h vs WHO
Fine particles PM_2.5	4.9 µg/m³	Good	0.5×
Coarse particles PM₁₀	5.3 µg/m³	Good	0.2×
Nitrogen dioxide NO₂	8.4 µg/m³	Good	0.8×
Ozone O₃	62 µg/m³	Good	0.4×
Sulphur dioxide SO₂	0.9 µg/m³	Good	0.0×
Carbon monoxide CO	159 µg/m³	Good	0.0×
Aerosol optical depth	0.12	Whole atmosphere · dimensionless
Desert dust	0 µg/m³	Modelled surface dust
UV index	1	Low

“Next 24 h vs WHO” compares the forecast with the World Health Organization’s 2021 guideline levels: 24-hour means of 15 µg/m³ for PM_2.5, 45 for PM₁₀, 25 for NO₂, 40 for SO₂ and 4 mg/m³ for CO, and 100 µg/m³ over 8 hours for ozone. Above 1× is above the guideline. Levels follow the US AQI, which is far less strict than the WHO, so air rated Good can still be above a guideline.

Next 48 hours

Hourly US AQI. Highest 59 around Fri 6:00 PM, lowest 17 around Sun 12:00 AM.

Good 0–50Moderate 51–100Sensitive 101–150Unhealthy 151–200Very unhealthy 201–300Hazardous 301+

5-day air quality forecast for Boston

Daily range of the hourly US AQI, from lowest to highest, on a scale of 0 to 150.

Day	US AQI	At worst	Worst hour	PM_2.5 avg	UV max
Fri, Nov 13	22–59	Moderate	6:00 PM	5.7	1 Low
Sat, Nov 14	20–48	Good	8:00 AM	4.5	2 Low
Sun, Nov 15	17–29	Good	1:00 PM	2.2	1 Low
Mon, Nov 16	18–48	Good	8:00 PM	4.1	2 Low
Tue, Nov 17	28–59	Moderate	6:00 PM	7.8	2 Low

Common questions about the air in Boston

Is the air in Boston safe today?
Yes. Right now the US AQI in Boston is 29, which counts as good. Great air. A perfect time to be outside. It is expected to reach 59 (moderate) around Fri 6:00 PM.
When is the best time to be outside in Boston?
Sat 9:00 AM–12:00 PM. That is the cleanest stretch in the next 24 hours, with the US AQI averaging about 25. The worst hour is around Fri 6:00 PM, at 59.
What is the main pollutant in Boston?
Ozone (O₃). It drives the index right now, at 62 µg/m³. Formed by sunlight acting on traffic and plant emissions. Highest on hot, still afternoons, often downwind of cities.
How does Boston's air compare with the WHO guideline?
Within the guideline. Over the next 24 hours PM_2.5 averages about 6.8 µg/m³, against the World Health Organization's 24-hour guideline of 15 µg/m³. The other pollutants stay within their guideline levels.
How many cigarettes is a day of Boston's air?
About 0.3 cigarettes. Over the next 24 hours PM_2.5 averages about 6.8 µg/m³. By Berkeley Earth's rule of thumb, 22 µg/m³ breathed for a day is roughly one cigarette.
Will air quality in Boston improve this week?
Sunday looks cleanest. Its AQI peaks at 29, against 59 on Friday, the worst day in the forecast.

Measured near Boston

Station and measurements	Distance	US AQI	Level
Boston - Chinatown AirNow, reference monitor PM_2.5: 4.7 µg/m³ · Fri 11:00 AM	1.1 km	26	Good
Unnamed sensor OpenAQ, low-cost sensor PM_2.5: 5.3 µg/m³ · Fri 12:00 PM	3.4 km	29	Good
Boston - Kenmore Sq AirNow, reference monitor PM_2.5: 3.0 µg/m³ · Fri 11:00 AM NO₂: 19 µg/m³ · Fri 11:00 AM SO₂: 3.7 µg/m³ · Fri 11:00 AM	3.4 km	17	Good

Air quality near Boston

US AQI right now. Cleanest nearby: Philadelphia (19); worst: Washington, D.C. (32). The tick on each bar is Boston, at 29.

New York 306 km SW 28 Good
Montreal 403 km NW 27 Good
Philadelphia 436 km SW 19 Good
Ottawa 504 km NW 30 Good
Washington, D.C. 634 km SW 32 Good
Toronto 692 km W 30 Good

All 162 cities →

About this forecast

Forecast from CAMS global via Open-Meteo: the Copernicus Atmosphere Monitoring Service (CAMS) model at about 40 km resolution (about 10 km inside Europe). Global runs update every 12 hours and European runs every 24 hours. Models smooth out street-level peaks, so busy roads and industrial sites can be worse than shown. Nearby station measurements are independent observations, not adjustments to the forecast. The point forecast uses Open-Meteo’s CAMS products, including a separate carbon monoxide product; it can differ from the globe’s global grid. The AQI rates each hour on the US EPA scale, the same way the map colors it; official daily figures average over 24 hours (8 for ozone), so they can read lower after a short peak. Readings for 42.36°N, 71.06°W, valid 2026-11-13 17:00 UTC.