Air Quality in Montreal, Quebec — Live
Live readings from PurpleAir sensors across Montreal — with free alerts the moment the air turns.
AQI 31 from 5 PurpleAir sensors · Holding steady · data from PurpleAir
As of , the air quality in Montreal, Quebec is AQI 31 — Good and holding steady — with PM2.5 at 5.5 µg/m³, the median of 5 live PurpleAir sensors reading 24 to 37. Canairy's verdict: Breathe easy.
For scale, that PM2.5 reading is below the World Health Organization's 24-hour guideline of 15 µg/m³. The WHO figure is a daily average and this is a live reading, so read it as a sense of magnitude rather than a formal exceedance — a brief spike and a bad day are not the same thing. More on the WHO guidelines
Pollen today in Montreal: weeds pollen is the strongest of the three at a very low level, from Google's pollen forecast. Canairy shows the tree, grass and weed forecast beside the air reading on every plan, including the free one.
Free to download · Live data from PurpleAir & public monitors
Live PurpleAir sensor map for Montreal and Laval, Longueuil, Westmount, Brossard. Every dot is a real sensor, color-coded by current air quality.
Sensor by sensor in Montreal
The sensors Canairy reads in Montreal agree right now — all 5 sit in the Good band, a 13-point spread — so the city-wide number is a fair description of the whole area today.
| From city center | AQI | Category |
|---|---|---|
| 0.9 mi NW | 31 | Good |
| 1.1 mi SSW | 37 | Good |
| 4.4 mi NNE | 29 | Good |
| 5.2 mi W | 35 | Good |
| 6.2 mi SSW | 24 | Good |
Montreal's bad-air days come in two seasons, from two sources that have almost nothing in common. In summer it is wildfire smoke arriving from somewhere far to the north: 25 and 26 June 2023 were the worst smog days ever recorded in the city, and at the time Montreal had the worst air quality in the world. In winter the source is a great deal closer to home — smoke from wood stoves and fireplaces settling over the island on cold, still nights. The city has spent more than fifteen years regulating that one, and the numbers show it worked.
What Canairy does for Montreal
A clear verdict
Not just a number — a plain-English call for Montreal: open the windows, or keep them shut.
Smoke alerts
A push or text the moment the air crosses your threshold — and again when it clears.
A heads-up before it's bad
Trend alerts catch the air turning, so you can close up the house before the smoke settles in.
Every place you care about
Home, work, the kids' school — across Montreal or across the country, on one screen.
The summer of 2023 was the worst on record
Quebec's 2023 forest fire season burned more than 4.3 million hectares, the most in the province's recorded history. Most of that was hundreds of kilometres north of the island, which made no difference at all to what people were breathing in Villeray or Verdun. The smoke arrived in late June and sat. The 25th and 26th were the worst smog days ever recorded in Montreal, and at the peak of it the city held the unwanted top spot on the global air quality rankings — worse, that morning, than anywhere else on earth.
The city's annual air quality report, published in July 2024, put the whole year in context: 2023 was Montreal's most polluted year for fine particles since 2015, and the fires were the reason. It is a useful thing to keep in mind when a smoke event starts. The trend in Montreal's air over the last decade has been downward, and then a fire season arrives and undoes a decade of progress for a fortnight.
The wood-burning bylaw, and why winter smog got rare
Wood heating is among the leading causes of winter smog in Montreal. The city first adopted a bylaw on solid-fuel appliances in 2009 and tightened it in 2015, and the rule now applies across all nineteen boroughs: you may not use a stove or fireplace unless it emits fewer than 2.5 grams of fine particles per hour, whatever fuel you are burning. If your appliance is not certified to that standard, the ban is in effect at all times. Even a compliant appliance cannot be used during a smog warning. The one common exemption is a power outage in your building lasting more than three hours.
Montreal sampled the air from 2009 to 2019 to find out whether any of it mattered, and it did. For the 2018-19 winter the city measured a 35 per cent drop in a chemical tracer of wood combustion compared with 2017-18. Winter smog days fell from 27 in 2008 to two in 2018. And the 2024 annual report found that pollution from residential wood heating dropped by nearly 40 per cent between 2014 and 2023. Which is why a smoky smell on a still January evening in a Montreal neighbourhood is much less common than it used to be — and worth checking a nearby sensor over, because when it does happen it is usually one chimney, close by, and not a regional event.
Montreal air quality FAQ
What is the air quality in Montreal right now?
As of September 10, 2026 at 8:10 AM EDT, the air quality in Montreal, Quebec is AQI 31 — Good — with PM2.5 at 5.5 µg/m³, the median of 5 live PurpleAir sensors. Open the windows. Great for outdoor activity.
Why is there smoke in Montreal today?
It depends on the season. From late spring through early autumn it is almost certainly wildfire smoke, usually from fires burning far to the north in Quebec or in Ontario — in June 2023 that smoke produced the worst smog days ever recorded here and briefly gave Montreal the worst air quality in the world. On a cold, still winter night it is far more likely to be residential wood burning close to you, which the city restricts precisely because it is among the leading causes of winter smog. The sensor map below usually settles which one it is: a wildfire event covers the whole island at once, while wood smoke shows up as one bad reading in one neighbourhood.
Canada reports the AQHI — why does this page show a different number?
Environment Canada reports air quality as the Air Quality Health Index, a 1-to-10+ scale of short-term health risk. This page does not show the AQHI. It shows the US EPA Air Quality Index, the 0-to-500 scale used by PurpleAir and most air-quality apps, so a Montreal reading is directly comparable with any other city on the map. The reason is practical: the AQHI is built from three pollutants together — ground-level ozone, nitrogen dioxide and fine particulate matter — and PurpleAir sensors measure only the fine particles. During wildfire smoke or a winter wood-smoke episode, when particles are the whole story, the two scales agree closely. On a hot, still summer afternoon with high ozone, the AQHI can read worse than a particle-only number, so check Environment Canada's AQHI alongside this page if ozone is your concern.
Can I use my fireplace in Montreal?
Only if it is certified to emit fewer than 2.5 grams of fine particles per hour. The city's solid-fuel bylaw, first adopted in 2009 and tightened in 2015, applies across all nineteen boroughs. A non-compliant stove or fireplace is banned at all times, and no wood-burning appliance may be used during a smog warning regardless of certification. The usual exemption is a power outage in your building lasting more than three hours. Check the City of Montreal's own page for the current certification list before you buy or install anything.
What the AQI numbers mean
| AQI | Category | What it means for you |
|---|---|---|
| 0–50 | Good | Open the windows. Great for outdoor activity. |
| 51–100 | Moderate | Sensitive groups may want to take it slower outside. |
| 101–150 | Unhealthy for Sensitive Groups | Kids, elderly, and respiratory conditions stay closer to home. |
| 151–200 | Unhealthy | Skip outdoor exercise. Close windows. |
| 201–300 | Very Unhealthy | Limit time outside. N95 if you must go. |
| 301+ | Hazardous | Health emergency. Stay inside, run filtration if you have it. |
Canairy lets you tighten these bands if you’re more sensitive than the EPA default, so an alert can fire before the official category changes. How to read the Air Quality Index
Where these readings come from
The AQI at the top of this page is the median of the 5 curated PurpleAir sensors Canairy tracks in and around Montreal, with outliers set aside so that one sensor brought indoors — or parked beside a barbecue — cannot set the number for a whole city. Every sensor behind it is listed above with its distance and bearing from the city center. There is no black box here.
In the app, a place you save resolves the same way first. When no neighborhood sensor is reporting it falls back to the nearest EPA AirNow monitor, and anything modeled rather than measured is labelled a regional estimate rather than passed off as a sensor reading. How low-cost sensors compare to regulatory monitors
About Canairy
Canairy is free to download. The free plan covers one saved place with live readings, a plain-English verdict, and push alerts when the air crosses a threshold you choose. Paid plans add more places, faster refreshes, and SMS alerts. It is built by two parents in Sonoma County, California, who got tired of guessing whether it was safe to send the kids outside. Why we built it
Go deeper
Air quality near Montreal
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