What is the air quality trend in Markham?

Over the past 4 days, Markham had an average AQI of 25 based on station measurements. The worst day was 2026-05-11 with AQI 61.

How is Markham air quality measured?

Air quality in Markham 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 Markham, Canada

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

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

Current AQI
Good Station

48 Hours 7 Days 14 Days 20 Days

CSV JSON

Air Quality Index Station

15h

PM2.5 Station

15h · 5 stations

Temperature GFS model

80pt

Precipitation GFS model

mm/day

Daily Summary Station

Date	AQI	Range	PM2.5 avg	PM10 avg	Hours	Stations
2026-05-22	24	20–27	5.7 µg/m³	—	2h	5
2026-05-13	3	1–5	0.6 µg/m³	0.8	3h	1
2026-05-11	61	10–132	19.6 µg/m³	23.4	8h	1
2026-05-10	14	14–14	1.7 µg/m³	2.0	2h	1

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