Air Quality in Montreal, Quebec — Live

Live readings from PurpleAir sensors across Montreal — with free alerts the moment the air turns.

Live Montreal AQI from nearby PurpleAir sensors loads when this page opens in a browser, along with a live sensor map covering Montreal and Laval, Longueuil, Westmount, Brossard.

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.

Canairy watches the sensors around your home, your kids' school, and everywhere else you care about, and tells you in plain English when the air changes enough to matter.

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

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.

What is the air quality in Montreal right now?

This page shows the current AQI for Montreal, calculated from PurpleAir sensors across the island and nearby communities, updated continuously. Sensor coverage here is thinner than in some larger North American cities, so check the map below to see which stations are actually reporting near you rather than relying on a single citywide number.

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 AQI level is unhealthy?

Under the US EPA scale, AQI 0–50 is Good and 51–100 is Moderate. From 101 the air is Unhealthy for Sensitive Groups — kids, older adults, and people with asthma or heart conditions — and above 150 it's Unhealthy for everyone. Canairy translates these numbers into a plain-English verdict, like whether to close the windows or move a workout indoors.

Is Canairy free?

Yes. The Canairy app is free to download and includes live air quality for all your saved places, plain-English verdicts, and free push alerts when the air crosses your threshold. A paid plan adds extras like SMS text alerts.

Get Canairy free on Google Play.