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)
23
Good
Waltham, Massachusetts
Last updated: ... (Local time)

Good
Fine
Moderate
Poor
Very poor
Hazardous
4.15 μg/m³
0
12.1
35.5
55.5
250.5
500.5+
18.05 μg/m³
0
55
155
255
425
605+
25.34 ppb
0
55
71
86
201
201+
0.73 ppb
0
36
76
186
605
1005+
2.66 ppb
0
54
101
361
1250
2050+
0.17 ppm
0
4.5
9.5
12.5
230.5
50.5+
Pollen Level
Low
Waltham, Massachusetts
Waltham, Massachusetts
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AQI 24
Good
4.06μg/m³
PM2.5
16.93μg/m³
PM10
26.49ppb
O3
0.68ppb
SO2
2.71ppb
NO2
0.19ppm
CO
AQI 24
Good
4.13μg/m³
PM2.5
16.06μg/m³
PM10
25.61ppb
O3
0.70ppb
SO2
2.63ppb
NO2
0.17ppm
CO
AQI 25
Good
4.07μg/m³
PM2.5
17.04μg/m³
PM10
26.52ppb
O3
0.68ppb
SO2
2.75ppb
NO2
0.19ppm
CO
AQI 24
Good
3.86μg/m³
PM2.5
16.10μg/m³
PM10
25.52ppb
O3
0.66ppb
SO2
2.60ppb
NO2
0.16ppm
CO
AQI 23
Good
3.84μg/m³
PM2.5
14.24μg/m³
PM10
25.35ppb
O3
0.63ppb
SO2
2.57ppb
NO2
0.20ppm
CO
AQI 25
Good
4.09μg/m³
PM2.5
17.18μg/m³
PM10
26.57ppb
O3
0.68ppb
SO2
2.78ppb
NO2
0.19ppm
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 11:00:00 on 2026-08-13.
In the last 24 hours, the best air quality in Waltham, Massachusetts was observed at 04:00:00 on 2026-08-14.
As of now, the AQI in Waltham, Massachusetts is 23, 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 4.149 μg/m3.
The PM10 concentration in Waltham, Massachusetts is 18.045 μg/m3 at the moment.
The current carbon monoxide (CO) concentration in Waltham, Massachusetts is 0.167 ppm.
Currently, Waltham, Massachusetts has a sulfur dioxide (SO2) concentration of 0.729 ppb.
The current ozone (O3) level in Waltham, Massachusetts at the moment is 25.34 ppm.
Nitrogen dioxide (NO2) level in Waltham, Massachusetts at the moment is 2.662 ppb.
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