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)
27
Good
Watertown, Massachusetts
Last updated: ... (Local time)

Good
Fine
Moderate
Poor
Very poor
Hazardous
5.29 μg/m³
0
12.1
35.5
55.5
250.5
500.5+
19.96 μg/m³
0
55
155
255
425
605+
26.21 ppb
0
55
71
86
201
201+
0.44 ppb
0
36
76
186
605
1005+
8.66 ppb
0
54
101
361
1250
2050+
0.24 ppm
0
4.5
9.5
12.5
230.5
50.5+
Pollen Level
Low
Watertown, Massachusetts
Watertown, Massachusetts
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AQI 38
Good
7.10μg/m³
PM2.5
27.50μg/m³
PM10
2.88ppb
O3
0.48ppb
SO2
18.90ppb
NO2
0.40ppm
CO
AQI 38
Good
6.59μg/m³
PM2.5
27.28μg/m³
PM10
5.73ppb
O3
0.44ppb
SO2
13.82ppb
NO2
0.38ppm
CO
AQI 49
Good
8.97μg/m³
PM2.5
37.88μg/m³
PM10
5.02ppb
O3
0.44ppb
SO2
13.20ppb
NO2
0.38ppm
CO
AQI 38
Good
7.17μg/m³
PM2.5
28.12μg/m³
PM10
2.97ppb
O3
0.48ppb
SO2
18.76ppb
NO2
0.40ppm
CO
AQI 38
Good
6.78μg/m³
PM2.5
27.97μg/m³
PM10
3.34ppb
O3
0.60ppb
SO2
17.91ppb
NO2
0.40ppm
CO
AQI 38
Good
6.77μg/m³
PM2.5
24.88μg/m³
PM10
2.81ppb
O3
0.53ppb
SO2
18.90ppb
NO2
0.40ppm
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 08:00:00 on 2025-11-03.
In the last 24 hrs, the best air quality in Watertown, Massachusetts was observed at 01:00:00 on 2025-11-02.
The current air quality in Watertown, Massachusetts is 38, 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 7.054 μg/m3.
The current PM10 concentration at Watertown, Massachusetts is 27.026 μg/m3.
The current carbon monoxide (CO) concentration at Watertown, Massachusetts is 0.4 ppm.
The current sulfur dioxide (SO2) concentration at Watertown, Massachusetts is 0.478 ppb.
The current ozone (O3) concentration at Watertown, Massachusetts is 2.824 ppm.
The current nitrogen dioxide (NO2) concentration at Watertown, Massachusetts is 18.993 ppb.
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