Stay updated with real-time air quality in Waltham, 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)
43
Good
Waltham, Massachusetts
Last updated: ... (Local time)

Good
Fine
Moderate
Poor
Very poor
Hazardous
4.27 μg/m³
0
12.1
35.5
55.5
250.5
500.5+
18.96 μg/m³
0
55
155
255
425
605+
46.44 ppb
0
55
71
86
201
201+
0.48 ppb
0
36
76
186
605
1005+
5.53 ppb
0
54
101
361
1250
2050+
0.20 ppm
0
4.5
9.5
12.5
230.5
50.5+
Pollen Level
Waltham, Massachusetts
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AQI 41
Good
4.19μg/m³
PM2.5
16.59μg/m³
PM10
43.66ppb
O3
0.61ppb
SO2
4.09ppb
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 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
4.39μg/m³
PM2.5
15.68μg/m³
PM10
43.79ppb
O3
0.48ppb
SO2
3.48ppb
NO2
0.20ppm
CO
AQI 42
Good
4.48μg/m³
PM2.5
20.25μg/m³
PM10
45.13ppb
O3
0.47ppb
SO2
3.29ppb
NO2
0.21ppm
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
Air quality and pollutant data for Massachusetts, USA are sourced from ground-based monitors and satellites, adhering to US EPA standards. Machine learning and advanced algorithms enhance the data by incorporating local variables like traffic and population density, ensuring high accuracy and dependability.
Source: Ambee Data Sources
The air quality information for Waltham, Massachusetts is updated every hour for accuracy.
In the past 24 hours, the air quality in Waltham, Massachusetts was at its worst at 10:00:00 on 2026-03-29.
In the last 24 hours, the best air quality in Waltham, Massachusetts was observed at 03:00:00 on 2026-03-29.
As of now, the AQI in Waltham, Massachusetts is 43, indicating Good conditions.
Waltham, Massachusetts air has the highest levels of O3.
Poor air quality in Waltham, Massachusetts means it's advisable to stay indoors and wear a mask for your protection.
PM2.5 levels in Waltham, Massachusetts are currently 4.27 μg/m3.
The PM10 concentration in Waltham, Massachusetts is 18.961 μg/m3 at the moment.
The current carbon monoxide (CO) concentration in Waltham, Massachusetts is 0.2 ppm.
Currently, Waltham, Massachusetts has a sulfur dioxide (SO2) concentration of 0.481 ppb.
The current ozone (O3) level in Waltham, Massachusetts at the moment is 46.439 ppm.
Nitrogen dioxide (NO2) level in Waltham, Massachusetts at the moment is 5.526 ppb.
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