What is the air quality trend in St. Thomas?

Over the past 4 days, St. Thomas had an average AQI of 177 based on station measurements. The worst day was 2026-07-17 with AQI 431.

How is St. Thomas air quality measured?

Air quality in St. Thomas 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 St. Thomas, Canada

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

Historical PM2.5 and AQI trend from monitoring stations near St. Thomas, Canada.

Current AQI
Moderate Station

48 Hours 7 Days 14 Days 20 Days

CSV JSON

Air Quality Index Station

16h

PM2.5 Station

16h · 2 stations

Temperature GFS model

28pt

Precipitation GFS model

mm/day

Daily Summary Station

Date	AQI	Range	PM2.5 avg	Hours	Stations
2026-07-20	85	60–110	28.2 µg/m³	6h	2
2026-07-19	111	85–174	48.0 µg/m³	4h	2
2026-07-18	84	35–179	38.5 µg/m³	4h	2
2026-07-17	431	411–451	413.7 µg/m³	2h	2

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