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)
49
Good
Watertown, Massachusetts
Last updated: ... (Local time)

Good
Fine
Moderate
Poor
Very poor
Hazardous
9.17 μg/m³
0
12.1
35.5
55.5
250.5
500.5+
36.96 μg/m³
0
55
155
255
425
605+
32.59 ppb
0
55
71
86
201
201+
1.12 ppb
0
36
76
186
605
1005+
6.86 ppb
0
54
101
361
1250
2050+
0.15 ppm
0
4.5
9.5
12.5
230.5
50.5+
Pollen Level
Low
Watertown, Massachusetts
Watertown, Massachusetts
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AQI 49
Good
9.15μg/m³
PM2.5
37.06μg/m³
PM10
32.64ppb
O3
1.12ppb
SO2
6.77ppb
NO2
0.15ppm
CO
AQI 56
Moderate
11.84μg/m³
PM2.5
42.61μg/m³
PM10
38.74ppb
O3
0.87ppb
SO2
6.05ppb
NO2
0.15ppm
CO
AQI 56
Moderate
11.63μg/m³
PM2.5
51.46μg/m³
PM10
38.36ppb
O3
0.90ppb
SO2
5.75ppb
NO2
0.15ppm
CO
AQI 49
Good
9.12μg/m³
PM2.5
37.17μg/m³
PM10
32.70ppb
O3
1.12ppb
SO2
6.67ppb
NO2
0.15ppm
CO
AQI 52
Moderate
9.68μg/m³
PM2.5
41.08μg/m³
PM10
35.12ppb
O3
1.22ppb
SO2
8.64ppb
NO2
0.15ppm
CO
AQI 49
Good
9.40μg/m³
PM2.5
37.31μg/m³
PM10
33.41ppb
O3
1.17ppb
SO2
7.99ppb
NO2
0.14ppm
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 06:00:00 on 2026-06-29.
In the last 24 hrs, the best air quality in Watertown, Massachusetts was observed at 09:00:00 on 2026-06-29.
The current air quality in Watertown, Massachusetts is 49, categorized as Good based on real-time data.
The most common pollutant in Watertown, Massachusetts is PM2.5.
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 9.171 μg/m3.
The current PM10 concentration at Watertown, Massachusetts is 36.96 μg/m3.
The current carbon monoxide (CO) concentration at Watertown, Massachusetts is 0.147 ppm.
The current sulfur dioxide (SO2) concentration at Watertown, Massachusetts is 1.124 ppb.
The current ozone (O3) concentration at Watertown, Massachusetts is 32.594 ppm.
The current nitrogen dioxide (NO2) concentration at Watertown, Massachusetts is 6.862 ppb.
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