City report · Ontario, Canada
Guelph Air quality today
Air quality in Guelph currently reads AQI 57 (Moderate): Unusually sensitive people should consider limiting long outdoor exertion.
Air quality right now
AQI 57
Moderate
- PM2.5, fine particles (µg/m³)
- 12.3
- tree cover
- 51.7%
- trees in this area
- 162K
- more trees needed
- 0
Measured across a 2 km radius around Exhibition Park, Guelph, ON, Canada (12.57 km²), from a satellite image of Aug 5, 2026. Lower AQI is better: 0–50 is Good, above 300 is Hazardous.
Guelph · AQI 57 (Moderate)
Guelph's tree count comes to 162,258 trees across 12.56 km² of land, already at or above the 30% tree-cover level considered healthy for this area.
Air quality detail
Air quality in Guelph today: AQI 57, 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 · Midtown Kitchener, 22.6 km away · median of 3 stations
Health signal
Unusually sensitive people should consider limiting long outdoor exertion.
PM2.5
12.3
PM10
—
NO₂
20.7
O₃
3.9
SO₂
—
CO
—
Data: OpenAQ · AirGradient, AirNow, FarmerAndy
- 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 Guelph's daily AQI at 20 on average, from 9 on Nov 9 to an hourly peak of 39 on Nov 5.
This is the US EPA AQI. How it differs from Canada's AQHI
Where Guelph stands: the most polluted cities in the world right now · the cleanest
Tree cover detail
Tree cover in Guelph: Healthy tree cover
51.7% tree cover against a 30% healthy-neighborhood target, across 12.56 km² of land.
Trees in this area
162,258
Target trees
162,258
More trees needed
0
CO₂ if planted / yr
0 kg
Deforestation · 2001–2025
How much forest has Guelph lost?
Since 2001, the area within 10 km of Guelph has lost about 112 hectares of forest (about 160 football pitches): 1.6% of the forest it had in 2000. Most of it (63%) was deforestation, forest cleared for good, mainly for towns and roads.
2017: satellite photo from September 2017 of a 5 × 5 km area in the city center.
- Forest lost since 2001
- 112 haabout 160 football pitches
- Share of its forest
- 1.6%of what there was in 2000
- Cleared for good
- 71 hadeforestation: turned into farms, mines or towns
The worst year was 2009, when about 12 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 | 3 ha | under 1 ha | 4 ha |
| 2002 | under 1 ha | under 1 ha | under 1 ha |
| 2003 | 2 ha | under 1 ha | 3 ha |
| 2004 | 4 ha | under 1 ha | 5 ha |
| 2005 | under 1 ha | 5 ha | 6 ha |
| 2006 | 1 ha | 2 ha | 3 ha |
| 2007 | 2 ha | 1 ha | 3 ha |
| 2008 | 1 ha | 2 ha | 3 ha |
| 2009 | 7 ha | 5 ha | 12 ha |
| 2010 | 3 ha | 8 ha | 11 ha |
| 2011 | 2 ha | under 1 ha | 3 ha |
| 2012 | under 1 ha | 1 ha | 1 ha |
| 2013 | 3 ha | under 1 ha | 3 ha |
| 2014 | 2 ha | under 1 ha | 2 ha |
| 2015 | 3 ha | under 1 ha | 3 ha |
| 2016 | 5 ha | under 1 ha | 6 ha |
| 2017 | 9 ha | 3 ha | 11 ha |
| 2018 | 4 ha | 3 ha | 7 ha |
| 2019 | 3 ha | 2 ha | 5 ha |
| 2020 | 5 ha | under 1 ha | 5 ha |
| 2021 | 2 ha | under 1 ha | 3 ha |
| 2022 | 5 ha | under 1 ha | 5 ha |
| 2023 | under 1 ha | under 1 ha | under 1 ha |
| 2024 | 1 ha | under 1 ha | 2 ha |
| 2025 | 2 ha | 5 ha | 7 ha |
What is causing deforestation around Guelph?
- Towns and roadscleared for good34% · 38 ha
- Farms, pasture and plantationscleared for good29% · 33 ha
- Loggingcan grow back19% · 21 ha
Also: storms, floods and other natural causes, mining and energy, unknown causes.
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
- 8,170 ha
- Forest in 2020
- 9,030 ha
- Overall change
- +856 hamore forest than in 2000
Comparing satellite maps from 2000 and 2020, the forest around Guelph grew from about 8,170 hectares to 9,030 hectares, a net gain of about 856 hectares (+10%). New forest grew on about 977 hectares, while 122 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
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Frequently asked
Questions about Guelph
What is the air quality (AQI) in Guelph right now?
The latest reading for Guelph shows an AQI of 57 (Moderate), measured Nov 11, 11:00 local time by 3 ground monitoring stations via OpenAQ (the median of their readings; the nearest is Midtown Kitchener, 22.6 km away). The main pollutant is PM2.5. Unusually sensitive people should consider limiting long outdoor exertion.
Is it safe to exercise outside in Guelph today?
At AQI 57 (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 Guelph been like this week?
Over the last 7 days, the CAMS air-quality model put Guelph's daily AQI at 20 on average, from 9 on Nov 9 to an hourly peak of 39 on Nov 5. No day averaged above 100, the level where the air turns unhealthy for sensitive groups.
Is Guelph'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 Guelph lost since 2001?
Since 2001, the area within 10 km of Guelph has lost about 112 hectares of forest (about 160 football pitches): 1.6% of the forest it had in 2000. Most of it (63%) was deforestation, forest cleared for good, mainly for towns and roads. Comparing satellite maps from 2000 and 2020, the forest around Guelph grew from about 8,170 hectares to 9,030 hectares, a net gain of about 856 hectares (+10%). New forest grew on about 977 hectares, while 122 hectares were lost.
What is the tree count in Guelph?
Guelph has an estimated 162,258 trees across the 12.56 km² of land measured — 51.7% tree cover, already past the 30% tree-cover target set for this area.
How many more trees does Guelph need?
Guelph has already reached its tree-cover target, so no additional trees are needed to close the gap.
How are Guelph's air quality and tree cover measured?
Air quality is measured by ground monitoring stations near Exhibition Park, 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 Exhibition Park; the tree count is an estimate derived from that cover.
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