Monitoring air quality in Montréal

Last updated July 19, 2023
Reading time: 2 min

The city has implemented a number of measures to monitor air quality in order to protect the environment and residents’ health. You can also do your part for air quality by taking simple actions.

Monitoring emissions produced by factories

Montréal has regulations that are in force all across the island of Montréal to reduce atmospheric emissions from the activities of thousands of manufacturing plants and factories. As well as regulating air quality, the city also monitors it through the Réseau de surveillance de la qualité de l’air (RSQA).

The Réseau de surveillance de la qualité de l’air

The Réseau de surveillance de la qualité de l’air has a team that measures, analyzes and validates the concentrations of pollutants in the surrounding air to provide a status of the stiuation. The 11 permanent sampling stations (in French) and the two temporary stations for special projects are spread out across the island of Montréal.

One of the two temporary stations is a nomad station in the Montréal-Est community gardens that was created there in 2022. The purpose of this station is to measure pollutants near factories. It will change location at the end of each project, and its duration can extend from 12 to 24 months. Data are made public every six months on the city’s open data Web site.

Tests conducted by the city

Analyzers are continually testing the concentration of pollutants to calculate the air quality index. This index measures air quality and is updated every hour. The index has three colours: good (green), acceptable (yellow) or poor (red). The result is a clear indicator of the level of pollution in the air. This indicator is broadcast on all platforms of the Weather Network and on the screens of Montréal’s subway system.

The primary pollutants measured by station are: 

  • Carbon monoxide (CO)
  • Nitrogen dioxide (NO2)
  • Ozone (O3) 
  • Fine particles (PM2.5)
  • Sulfur dioxide (SO2)

A number of other pollutants, such as ultrafine particles and arsenic, are measured occasionally or continuously by the air quality surveillance network. Visit the open data page to see them. 

How can we do our part for air quality?

You can help improve Montréal’s air quality by:

Did you know that wood heating is one of the main causes of wintertime smog in Montréal? It is prohibited to use a wood-burning stove or fireplace during smog warnings. This prohibition is in effect at all times if your appliance is not compliant with emission regulations.

Smog alerts

To get smog alerts on your phone, download the Weather Can mobile app.

Alerts issued by Environment Canada are integrated into the app.