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

Good
Fine
Moderate
Poor
Very poor
Hazardous
4.01 μg/m³
0
12.1
35.5
55.5
250.5
500.5+
12.88 μg/m³
0
55
155
255
425
605+
44.65 ppb
0
55
71
86
201
201+
0.35 ppb
0
36
76
186
605
1005+
2.97 ppb
0
54
101
361
1250
2050+
0.17 ppm
0
4.5
9.5
12.5
230.5
50.5+
Pollen Level
Leominster, Massachusetts
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AQI 42
Good
3.49μg/m³
PM2.5
9.95μg/m³
PM10
44.65ppb
O3
0.38ppb
SO2
2.15ppb
NO2
0.17ppm
CO
AQI 41
Good
3.98μg/m³
PM2.5
9.07μg/m³
PM10
44.36ppb
O3
0.40ppb
SO2
2.58ppb
NO2
0.17ppm
CO
AQI 42
Good
4.10μg/m³
PM2.5
15.84μg/m³
PM10
44.70ppb
O3
0.32ppb
SO2
3.19ppb
NO2
0.18ppm
CO
AQI 41
Good
3.92μg/m³
PM2.5
10.09μg/m³
PM10
44.48ppb
O3
0.43ppb
SO2
2.61ppb
NO2
0.18ppm
CO
AQI 42
Good
4.06μg/m³
PM2.5
15.56μg/m³
PM10
44.93ppb
O3
0.43ppb
SO2
4.30ppb
NO2
0.18ppm
CO
AQI 42
Good
3.85μg/m³
PM2.5
9.86μg/m³
PM10
44.66ppb
O3
0.37ppb
SO2
2.53ppb
NO2
0.19ppm
CO
The air quality data for Massachusetts, USA is gathered from reliable sources such as satellites and monitoring stations, adhering to US EPA guidelines. With the help of advanced algorithms and machine learning, factors like traffic and population density are analyzed to deliver accurate and dependable results.
Source: Ambee Data Sources
Air quality updates for Leominster, Massachusetts are available every hour.
Leominster, Massachusetts experienced its worst air quality at 10:00:00, 2026-03-29.
The best air quality in Leominster, Massachusetts was observed at 12:00:00 on 2026-03-29.
The air quality in Leominster, Massachusetts right now is Good, with an AQI of 42.
In Leominster, Massachusetts, O3 is the most frequently found pollutant.
When air quality in Leominster, Massachusetts is compromised, staying indoors and wearing a mask can reduce health risks.
Leominster, Massachusetts currently has a PM2.5 concentration of 4.011 μg/m3.
Leominster, Massachusetts currently has a PM10 concentration of 12.885 μg/m3.
The current carbon monoxide (CO) level in Leominster, Massachusetts is 0.174 ppm.
The current sulfur dioxide (SO2) concentration in Leominster, Massachusetts is 0.352 ppb.
Leominster, Massachusetts currently has an ozone (O3) concentration of 44.652 ppm.
The current level of nitrogen dioxide (NO2) in Leominster, Massachusetts is 2.966 ppb.
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