What is the air quality trend in Williamstown?

Over the past 8 days, Williamstown had an average AQI of 90 based on station measurements. The worst day was 2026-07-17 with AQI 184.

How is Williamstown air quality measured?

Air quality in Williamstown is measured by ground-level monitoring stations that report PM2.5 and PM10 concentrations hourly. CERNS.IO aggregates readings from nearby stations and converts PM2.5 to the US EPA Air Quality Index (AQI) scale.

Air Quality History for Williamstown, United States

Name: Williamstown Air Quality History
Creator: CERNS.IO
License: https://creativecommons.org/licenses/by/4.0/

Historical PM2.5 and AQI trend from monitoring stations near Williamstown, United States.

Current AQI
Good CAMS model

48 Hours 7 Days 14 Days 20 Days

CSV JSON

Air Quality Index Station

168h

PM2.5 Station

168h · 5 stations

Temperature GFS model

28pt

Precipitation GFS model

mm/day

Daily Summary Station

Date	AQI	Range	PM2.5 avg	PM10 avg	Hours	Stations
2026-07-22	30	29–32	7.4 µg/m³	4.7	2h	44
2026-07-21	55	35–66	14.4 µg/m³	22.5	24h	83
2026-07-20	48	30–75	12.7 µg/m³	13.1	24h	80
2026-07-19	58	26–74	16.4 µg/m³	26.2	24h	82
2026-07-18	142	72–168	62.9 µg/m³	95.6	24h	83
2026-07-17	184	159–229	115.2 µg/m³	143.8	24h	87
2026-07-16	148	87–176	60.4 µg/m³	96.1	24h	80
2026-07-15	57	53–63	15.0 µg/m³	23.2	22h	84

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