City report · Ontario, Canada
Hamilton Air quality today
Air quality in Hamilton currently reads AQI 53 (Moderate): Unusually sensitive people should consider limiting long outdoor exertion.
AQI 53
Air quality right now
Moderate
- PM2.5, fine particles (µg/m³)
- 10.0
- tree cover
- 28.1%
- trees in this area
- 88.3K
- more trees needed
- 6.0K
Measured across a 2 km radius around St. Clair, Hamilton, ON, Canada (12.57 km²), from a satellite image of Aug 25, 2026. Lower AQI is better: 0–50 is Good, above 300 is Hazardous.
Hamilton · AQI 53 (Moderate)
Hamilton's tree count comes to 88,279 trees across 12.57 km², 2 points below the 30% tree-cover level considered healthy for this area, so roughly 5,969 more trees would close the gap.
Air quality detail
Air quality in Hamilton today: AQI 53, Moderate
Main pollutant: PM2.5 · Observed Nov 11, 11:00 local time via OpenAQ ground stations, US EPA index. Values in µg/m³.
Ground station · Hamilton Mountain, 3.4 km away · median of 4 stations
Health signal
Unusually sensitive people should consider limiting long outdoor exertion.
PM2.5
10.0
PM10
—
NO₂
26.3
O₃
21.6
SO₂
—
CO
—
Data: OpenAQ · AirNow
- Outdoor exercise
- Fine for most people; unusually sensitive people should take long or hard exercise easier
- Windows
- Fine to open; close them if you are sensitive to pollution
- Mask
- Not needed for most people
- Air purifier
- Worth running if you are sensitive
Over the last 7 days, the CAMS air-quality model put Hamilton's daily AQI at 24 on average, from 11 on Nov 9 to an hourly peak of 51 on Nov 8.
This is the US EPA AQI. How it differs from Canada's AQHI
Where Hamilton stands: the most polluted cities in the world right now · the cleanest
Tree cover detail
Tree cover in Hamilton: Below target
28.1% tree cover against a 30% healthy-neighborhood target, across 12.57 km².
Trees in this area
88,279
Target trees
94,248
More trees needed
5,969
CO₂ if planted / yr
131.3 t
Deforestation · 2001–2025
How much forest has Hamilton lost?
Since 2001, the area within 10 km of Hamilton has lost about 58 hectares of forest (about 82 football pitches): 1.3% of the forest it had in 2000. Most of it (84%) was deforestation, forest cleared for good, mainly for towns and roads.
2017: satellite photo from June 2017 of a 5 × 5 km area in the city center.
- Forest lost since 2001
- 58 haabout 82 football pitches
- Share of its forest
- 1.3%of what there was in 2000
- Cleared for good
- 49 hadeforestation: turned into farms, mines or towns
The worst year was 2004, when about 9 hectares of forest were lost.
Hectares of forest lost each year
Show the figures as a table
| Year | Cleared for good | Can grow back | Total |
|---|---|---|---|
| 2001 | under 1 ha | under 1 ha | under 1 ha |
| 2002 | 3 ha | under 1 ha | 4 ha |
| 2003 | under 1 ha | under 1 ha | under 1 ha |
| 2004 | 7 ha | 1 ha | 9 ha |
| 2005 | 6 ha | under 1 ha | 6 ha |
| 2006 | 2 ha | under 1 ha | 2 ha |
| 2007 | 1 ha | under 1 ha | 2 ha |
| 2008 | 4 ha | under 1 ha | 5 ha |
| 2009 | under 1 ha | under 1 ha | under 1 ha |
| 2010 | 1 ha | under 1 ha | 2 ha |
| 2011 | 1 ha | under 1 ha | 2 ha |
| 2012 | under 1 ha | under 1 ha | under 1 ha |
| 2013 | 3 ha | under 1 ha | 3 ha |
| 2014 | 1 ha | under 1 ha | 2 ha |
| 2015 | under 1 ha | under 1 ha | under 1 ha |
| 2016 | 3 ha | under 1 ha | 3 ha |
| 2017 | 4 ha | under 1 ha | 4 ha |
| 2018 | under 1 ha | under 1 ha | 1 ha |
| 2019 | under 1 ha | under 1 ha | 1 ha |
| 2020 | under 1 ha | under 1 ha | under 1 ha |
| 2021 | 8 ha | under 1 ha | 8 ha |
| 2022 | under 1 ha | under 1 ha | under 1 ha |
| 2023 | under 1 ha | under 1 ha | under 1 ha |
| 2024 | under 1 ha | under 1 ha | under 1 ha |
| 2025 | under 1 ha | under 1 ha | under 1 ha |
What is causing deforestation around Hamilton?
- Towns and roadscleared for good84% · 49 ha
- Unknown causescause unknown15% · 9 ha
Also: logging.
Causes for 2025 are estimates, based on what caused forest loss in the same places up to 2024.
Forest gained and lost, 2000–2020
- Forest in 2000
- 8,160 ha
- Forest in 2020
- 8,520 ha
- Overall change
- +360 hamore forest than in 2000
Comparing satellite maps from 2000 and 2020, the forest around Hamilton grew from about 8,160 hectares to 8,520 hectares, a net gain of about 360 hectares (+4.4%). New forest grew on about 596 hectares, while 236 hectares were lost.
These 2000 and 2020 maps, from the University of Maryland, count any land with trees taller than 5 m as forest, including plantations and orchards. Forest that was cut or burned and had grown back by 2020 counts in both years, so the loss here is smaller than the yearly figures.
These figures cover everything within 10 km of the city center, a wider area than the report above, because forest is usually lost at a city's edges.
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. Forest gained and lost 2000–2020: Potapov et al. 2022, UMD GLAD Global Land Cover and Land Use Change, CC BY 4.0. Images: contains modified Copernicus Sentinel data. How it's measured
In the same region
Measured cities near Hamilton
Same 2 km radius, same index — so they compare directly.
- Burlington15.2 km
Canada
- Tree cover
- 40%
- Air quality
- 39
- Oakville26.0 km
Canada
- Tree cover
- 44%
- Air quality
- 29
- Milton29.8 km
Canada
- Tree cover
- 35%
- Air quality
- 28
- Brantford36.2 km
Canada
- Tree cover
- 37%
- Air quality
- 79
- Cambridge39.4 km
Canada
- Tree cover
- 42%
- Air quality
- 79
- Mississauga39.7 km
Canada
- Tree cover
- 23%
- Air quality
- 58
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Frequently asked
Questions about Hamilton
What is the air quality (AQI) in Hamilton right now?
The latest reading for Hamilton shows an AQI of 53 (Moderate), measured Nov 11, 11:00 local time by 4 ground monitoring stations via OpenAQ (the median of their readings; the nearest is Hamilton Mountain, 3.4 km away). The main pollutant is PM2.5. Unusually sensitive people should consider limiting long outdoor exertion.
Is it safe to exercise outside in Hamilton today?
At AQI 53 (Moderate): fine for most people; unusually sensitive people should take long or hard exercise easier. Windows: fine to open; close them if you are sensitive to pollution. Masks: not needed for most people. The reading changes through the day, so check again before a long run or ride.
What has the air quality in Hamilton been like this week?
Over the last 7 days, the CAMS air-quality model put Hamilton's daily AQI at 24 on average, from 11 on Nov 9 to an hourly peak of 51 on Nov 8. No day averaged above 100, the level where the air turns unhealthy for sensitive groups.
Is Hamilton's AQI 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.
How much forest has the area around Hamilton lost since 2001?
Since 2001, the area within 10 km of Hamilton has lost about 58 hectares of forest (about 82 football pitches): 1.3% of the forest it had in 2000. Most of it (84%) was deforestation, forest cleared for good, mainly for towns and roads. Comparing satellite maps from 2000 and 2020, the forest around Hamilton grew from about 8,160 hectares to 8,520 hectares, a net gain of about 360 hectares (+4.4%). New forest grew on about 596 hectares, while 236 hectares were lost.
What is the tree count in Hamilton?
Hamilton has an estimated 88,279 trees across the 12.57 km² measured — 28.1% tree cover, 2 percentage points short of the 30% tree-cover target set for this area.
How many more trees does Hamilton need?
Hamilton needs roughly 5,969 more trees to close a 2-point shortfall against its 30% tree-cover target — about 131.3 t of extra CO₂ absorbed per year once grown.
How are Hamilton's air quality and tree cover measured?
Air quality is measured by ground monitoring stations near St. Clair, via OpenAQ; the 7-day trend is the Open-Meteo / CAMS model's estimate. Tree cover is measured from Sentinel-2 L2A (ESA Copernicus) via Earth Search satellite imagery at 10 m detail across a 2 km radius around St. Clair; the tree count is an estimate derived from that cover.
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