Air quality comparison · Canada, 165 km apart
Montréal vs Ottawa Air quality index (AQI) today
Montréal has cleaner air than Ottawa right now: AQI 12 (Good) against 31 (Good).
Both sit in the same EPA band, so the health advice is the same for each today. But over the past 7 days, on modeled daily averages, Ottawa averaged AQI 26 against 36, and it was the cleaner of the two on 5 of those days. Ottawa has lost more forest since 2001. Montréal has more tree cover.
Updated . Lower is better on the US EPA index: 0–50 is Good, above 300 is Hazardous. Measured by Airleaf.
Montréal12Ottawa31
Head to head
Montréal vs Ottawa at a glance
Montréal is ahead on 5 of 6 measures, and Ottawa on 1. The better figure in each row is marked.
| Montréal | Ottawa | |
|---|---|---|
| Air quality nowUS AQI. Lower is better. | 12 (better) | 31 |
| PM2.5Fine particles, µg/m³. | 2.2 (better) | 5.5 |
| Past week's averageUS AQI, 7 days. | 36 | 26 (better) |
| Forest lost since 2001Within 10 km of the center. | 23 ha (better) | 302 ha |
| Tree coverWithin 2 km of the center. | 44.4% (better) | 22.4% |
| Trees still neededTo reach a healthy canopy. | 0 (better) | 22.2K |
Air quality today
What is the air like in Montréal and Ottawa right now?
Montréal has cleaner air than Ottawa right now: AQI 12 (Good) against 31 (Good). PM2.5 is setting the index in both.
Both readings come from nearby ground stations.
MontréalOttawa
Concentrations at the same moment as the index above, for the pollutants both places report. Lower is better. The dark marks on the PM2.5 and PM10 rows show the WHO's 24-hour guidelines (15 and 45 µg/m³).
The past week
Which had cleaner air over the past 7 days?
But over the past 7 days, on modeled daily averages, Ottawa averaged AQI 26 against 36, and it was the cleaner of the two on 5 of those days. A single reading can catch a city on a bad afternoon; the week says whether it was the weather or the place.
- Cleaner days
- Montréal2Ottawa5
- Average AQI
- Montréal36Ottawa26
- Worst day, AQI
- Montréal51Ottawa51
The daily numbers (7 days)
| Day | Montréal | Ottawa |
|---|---|---|
| Nov 5 | 33 | 19 |
| Nov 6 | 43 | 28 |
| Nov 7 | 45 | 51 |
| Nov 8 | 31 | 34 |
| Nov 9 | 38 | 16 |
| Nov 10 | 51 | 34 |
| Nov 11 | 9 | 2 |
Daily averages from the CAMS atmospheric model for both places, so the week compares like with like. They can differ from today's reading at the top of the page wherever that comes from a ground station.
What it means today
Is it safe to go outside in Montréal and Ottawa today?
Air quality is satisfactory for everyone. Both are in the same EPA band today (Good), so the advice is the same.
Exercise outdoors
A good day to be active outside.
Windows
Open them to air the house.
Masks
Not needed.
Air purifier
Not needed.
Against everywhere else
How do Montréal and Ottawa compare with the rest of the world?
Right now Montréal's air is cleaner than 95% of the 5,420 places Airleaf tracks, and Ottawa's is cleaner than 80%. Within Canada, that is 90% and 36% of its 59 measured places.
Cleaner air than…
- Montréal
- Beats 95%
- Ottawa
- Beats 80%
More tree cover than…
- Montréal
- Beats 88%
- Ottawa
- Beats 52%
Includes model estimates as well as station readings, so it can differ from our most polluted and cleanest air rankings, which use station readings only.
Deforestation · 2001–2025
Which has lost more forest, Montréal or Ottawa?
Ottawa has lost more: about 302 ha of forest within 10 km of its center from 2001 to 2025, against 23 ha around Montréal. 257 ha of that was cleared for good, for farms, mines or towns.
Measured within 10 km of each center, from the yearly satellite maps of forest loss: a wider circle than the one for tree cover, because forest is usually lost at a city's edges.
Worst year: 2004, with 5 ha lost.
Worst year: 2022, with 44 ha lost.
| Montréal | Ottawa | |
|---|---|---|
| Forest lost since 2001Cleared, burned or logged. | 23 ha (better) | 302 ha |
| Share of its forestOf what it had in 2000. | 1.4% (better) | 4.1% |
| Cleared for goodTurned into farms, mines or towns. | 18 ha (better) | 257 ha |
| Recent trend2021–2025 against the five years before. | Too little to call | Too little to call |
| Main known cause | Towns and roads (76%) | Towns and roads (85%) |
Satellite timelapses
Watch both change, year by year
A clear satellite photo a year of the land around each city. Press play, turn on the forest cleared since the first year, or drag the before and after.
Montréal
2017: satellite photo from September 2017 of a 5 × 5 km area in the city center.
Ottawa
2017: satellite photo from September 2017 of a 5 × 5 km area about 7 km west of the city center.
Trees
Which has more trees, Montréal or Ottawa?
Montréal has more tree cover: 44.4% of the land within 2 km of its center against 22.4% around Ottawa, or about 139,208 trees against 65,305.
The dark mark is each place's canopy target: 30% of the land, raised where air quality is poor.
| Montréal | Ottawa | |
|---|---|---|
| Trees standingEstimated from the canopy area. | 139K (better) | 65.3K |
| Trees still neededTo reach the target. Fewer is better. | 0 (better) | 22.2K |
| CO₂ absorbed each yearBy the trees already standing. | 3.1M kg (better) | 1.4M kg |
Tree cover on the satellite image
The same 2 km radius around each center, with the tree cover the satellite found marked on it.
Reading these numbers
How this comparison is made
Air quality index
The US EPA index, computed from current pollutant concentrations: ground stations where a place has them nearby, and the CAMS atmospheric model everywhere else. It moves hour to hour, so it is a snapshot rather than a verdict on either place. The guideline marks are from the WHO's 2021 air quality guidelines.
Trees and forest
Tree cover is the share of ground under canopy within 2 km of each center, read from Sentinel-2 satellite imagery at 10 m detail. It measures that circle, not the whole municipality, which is what makes the two comparable. Forest loss comes from the University of Maryland's Global Forest Change maps.
More on the method on the About Airleaf page.
Frequently asked
Montréal vs Ottawa: your questions answered
Is Montréal cleaner than Ottawa?
On air quality, yes, right now: Montréal reads AQI 12 against 31, a gap of 19 points on the US EPA index. This is a live reading rather than an annual average, so it can reverse within a day. But over the past 7 days, on modeled daily averages, Ottawa averaged AQI 26 against 36, and it was the cleaner of the two on 5 of those days.
Is it safe to exercise outdoors in Montréal and Ottawa today?
The advice is the same for both today. Air quality is satisfactory for everyone. Montréal reads AQI 12 and Ottawa reads AQI 31.
Which has lost more forest, Montréal or Ottawa?
Ottawa has lost more: about 302 ha of forest within 10 km of its center from 2001 to 2025, against 23 ha around Montréal. 257 ha of that was cleared for good, for farms, mines or towns.
Which has more trees, Montréal or Ottawa?
Montréal has more tree cover: 44.4% of the land within 2 km of its center against 22.4% around Ottawa, or about 139,208 trees against 65,305. Both figures describe the same-sized circle of ground around each center, not the whole municipality.
How many more trees do Montréal and Ottawa need?
Montréal needs about 0 more to reach its canopy target of 30%, and Ottawa about 22,157 to reach 30%. The target starts at 30% of the land and rises where air quality is poor.
Are Montréal and Ottawa measured the same way?
The method is the same: the US EPA index for air, and Sentinel-2 satellite imagery at 10 m detail over an identical radius for trees. Both readings come from nearby ground stations. Nothing is adjusted for population, city limits or climate.
How often does the Montréal vs Ottawa comparison update?
The air readings refresh about once an hour, and each reading's local time is shown at the top of the page. Tree cover comes from the latest clear satellite image of each area (Sep 11, 2026 and Sep 11, 2026), and the forest figures are published yearly.
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