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Air quality now: Toronto

Canada · Ontario · 26 cities

Air quality in Ontario today The AQI right now, city by city

Right now, Nepean has the cleanest air of the 26 cities we track in Ontario (AQI 6, Good), and Windsor the worst (AQI 70, Moderate). Guelph has the most tree cover, at 51.7% — #3 of 59 cities measured in Canada.

Every city is measured the same way, over the same 2 km around its center: the air quality right now, from ground stations where there are any, and its tree cover.

AQI 34

Average right now

Good

US EPA index, across 26 cities
cities tracked
26
average tree cover
33.3%
Canada: 33.1%
worst air now: Windsor
70
cleanest air now: Nepean
6

Lower is better on the US EPA index: 0–50 is Good, above 300 is Hazardous, and it reads differently from Canada's AQHI. Measured by Airleaf, refreshed hourly.

Ontario · average AQI 34

Air quality today across Ontario, city by city

Current air quality and tree cover for cities in Ontario, Canada
Toronto44Good15.6%42.5K#58 of 59
Ottawa19Good22.4%22.2K#53 of 59
Mississauga24Good22.8%22.6K#51 of 59
Brampton26Good37.3%—#20 of 59
Hamilton50Good28.1%6.0K#39 of 59
London28Good31.4%—#32 of 59
Etobicoke53Moderate36.3%—#25 of 59
Markham33Good39.2%—#15 of 59
Vaughan33Good19.3%33.6K#56 of 59
Kitchener36Good38.7%—#16 of 59
Windsor70Moderate25.6%13.7K#45 of 59
Oakville20Good44.4%—#7 of 59
Burlington50Good39.7%—#12 of 59
Nepean6Good37.0%—#22 of 59
Oshawa20Good38.1%—#18 of 59
Greater Sudbury53Moderate45.1%—#6 of 59
Barrie28Good39.2%—#14 of 59
Guelph35Good51.7%—#3 of 59
St. Catharines26Good32.8%—#29 of 59
Milton39Good34.9%—#28 of 59
Kingston11Good28.0%3.0K#40 of 59
Cambridge55Moderate42.4%—#9 of 59
Orléans19Good27.2%8.8K#42 of 59
Ajax23Good23.4%20.7K#48 of 59
Thunder Bay17Good29.7%869#36 of 59
Brantford55Moderate36.5%—#23 of 59

Air quality is the US AQI from ground monitoring stations via OpenAQ where available, otherwise the Open-Meteo / CAMS model, refreshed hourly. Tree cover is measured within 2 km of each city center from Sentinel-2 imagery; the rank compares every city measured in Canada.

Is this the same as Canada's AQHI?

No. Airleaf shows the US EPA Air Quality Index (AQI), the scale used by IQAir and most air-quality apps. Canada's Air Quality Health Index (AQHI), from Environment and Climate Change Canada, runs from 1 to 10 and above: 1–3 low risk, 4–6 moderate, 7–10 high and over 10 very high. It combines ozone, nitrogen dioxide and fine particles into one health-risk number, so it isn't a converted AQI, and the two can move differently, especially in wildfire smoke.

Deforestation · 2001–2025

How much forest has Ontario lost?

Since 2001, Ontario has lost about 6.53 million hectares of forest (about 65,000 km²): 9.2% of the forest it had in 2000. Most of it was lost to logging, so much of it can grow back. About 103,000 hectares (1.6%) was deforestation: forest cleared for good for farms, mines or towns.

Forest lost since 2001
6.53 million haabout 65,000 km²
Share of its forest
9.2%of what there was in 2000
Cleared for good
103,000 hadeforestation: turned into farms, mines or towns
Forest lost each year in Ontario, 2001–2025

Hectares of forest lost each year

Forest lost each year in Ontario, 2001–2025. Use the left and right arrow keys to read each year.479K

Show the figures as a table
Forest lost each year in Ontario, 2001–2025
YearCleared for goodCan grow backTotal
20012,860 ha186,000 ha188,000 ha
20022,740 ha326,000 ha329,000 ha
20031,490 ha276,000 ha278,000 ha
20043,640 ha322,000 ha326,000 ha
20053,800 ha281,000 ha285,000 ha
20063,440 ha235,000 ha238,000 ha
20074,240 ha264,000 ha268,000 ha
20083,550 ha158,000 ha162,000 ha
20092,800 ha119,000 ha122,000 ha
20103,560 ha116,000 ha119,000 ha
20113,900 ha319,000 ha323,000 ha
20124,950 ha384,000 ha388,000 ha
20133,180 ha158,000 ha162,000 ha
20143,070 ha141,000 ha144,000 ha
20153,760 ha151,000 ha155,000 ha
20165,610 ha215,000 ha220,000 ha
20176,090 ha197,000 ha203,000 ha
20185,990 ha306,000 ha312,000 ha
20194,630 ha299,000 ha303,000 ha
20204,540 ha189,000 ha194,000 ha
20215,560 ha404,000 ha410,000 ha
20224,830 ha322,000 ha327,000 ha
20233,790 ha380,000 ha384,000 ha
20243,360 ha204,000 ha208,000 ha
20257,640 ha471,000 ha479,000 ha

Forest loss is speeding up: about 362,000 hectares a year in 2021–2025, up from 246,000 hectares a year in 2016–2020. The worst year was 2025, when about 479,000 hectares of forest were lost.

What is causing deforestation in Ontario?

  • Loggingcan grow back54% · 3.52 million ha
  • Wildfirescan grow back37% · 2.39 million ha
  • Storms, floods and other natural causescan grow back3.3% · 216,000 ha

Also: farms, pasture and plantations, mining and energy, towns and roads, unknown causes.

Causes for 2025 are estimates, based on what caused forest loss in the same places up to 2024.

Source: Hansen/UMD/Google/USGS/NASA, Global Forest Change (GFC-2025-v1.13); causes: WRI/Google DeepMind drivers of forest loss; both CC BY 4.0, summed by Airleaf for each area. How it's measured

Other provinces in Canada

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