Stay updated with real-time air quality in Watertown, Massachusetts featuring accurate data on AQI, PM2.5, PM10, O3, NO2, SO2, and CO levels. Use our interactive map and detailed forecasts to monitor pollution trends, manage health risks, and plan your daily activities with confidence.
Live AQI (Air Quality Index)
42
Good
Watertown, Massachusetts
Last updated: ... (Local time)

Good
Fine
Moderate
Poor
Very poor
Hazardous
4.30 μg/m³
0
12.1
35.5
55.5
250.5
500.5+
17.02 μg/m³
0
55
155
255
425
605+
44.80 ppb
0
55
71
86
201
201+
0.58 ppb
0
36
76
186
605
1005+
5.19 ppb
0
54
101
361
1250
2050+
0.20 ppm
0
4.5
9.5
12.5
230.5
50.5+
Pollen Level
Watertown, Massachusetts
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AQI 41
Good
4.18μg/m³
PM2.5
16.67μg/m³
PM10
43.67ppb
O3
0.61ppb
SO2
4.10ppb
NO2
0.20ppm
CO
AQI 41
Good
4.36μg/m³
PM2.5
19.74μg/m³
PM10
44.42ppb
O3
0.52ppb
SO2
3.39ppb
NO2
0.20ppm
CO
AQI 42
Good
4.32μg/m³
PM2.5
15.14μg/m³
PM10
44.64ppb
O3
0.52ppb
SO2
3.92ppb
NO2
0.20ppm
CO
AQI 41
Good
4.18μg/m³
PM2.5
16.77μg/m³
PM10
43.69ppb
O3
0.61ppb
SO2
4.11ppb
NO2
0.20ppm
CO
AQI 41
Good
4.20μg/m³
PM2.5
17.81μg/m³
PM10
43.90ppb
O3
0.66ppb
SO2
3.99ppb
NO2
0.20ppm
CO
AQI 41
Good
4.20μg/m³
PM2.5
16.40μg/m³
PM10
43.69ppb
O3
0.64ppb
SO2
3.90ppb
NO2
0.18ppm
CO
Air quality data and pollutant measurements for Massachusetts, USA adhere to strict US EPA standards. The data is collected from multiple reliable sources, including satellites and ground-based monitoring stations. This data is further analyzed and enhanced using machine learning and advanced algorithms that factor in elements such as traffic and population density, ensuring accurate and reliable results.
Source: Ambee Data Sources
The air quality for Watertown, Massachusetts is updated every hour.
The worst air quality in Watertown, Massachusetts in the last 24 hours was observed at 10:00:00 on 2026-03-29.
In the last 24 hrs, the best air quality in Watertown, Massachusetts was observed at 03:00:00 on 2026-03-29.
The current air quality in Watertown, Massachusetts is 42, categorized as Good based on real-time data.
The most common pollutant in Watertown, Massachusetts is O3.
If the air quality in Watertown, Massachusetts is poor, consider staying indoors and wearing a mask to protect yourself.
The current PM2.5 concentration at Watertown, Massachusetts is 4.304 μg/m3.
The current PM10 concentration at Watertown, Massachusetts is 17.016 μg/m3.
The current carbon monoxide (CO) concentration at Watertown, Massachusetts is 0.197 ppm.
The current sulfur dioxide (SO2) concentration at Watertown, Massachusetts is 0.577 ppb.
The current ozone (O3) concentration at Watertown, Massachusetts is 44.795 ppm.
The current nitrogen dioxide (NO2) concentration at Watertown, Massachusetts is 5.187 ppb.
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