Smog and heat warning

Heat warning

Heat warnings are issued when very high temperature or humidity conditions are expected to pose an elevated risk of heat illnesses, such as heat stroke or heat exhaustion. During very hot weather, some people are at greater risk of developing health problems, notably older persons, children under 5 years of age, persons with chronic illnesses, including heart and lung disease and people with mental health problems or drug or alcohol problems.

The main problems linked to the heat are dehydration, headaches, dizziness, confusion or fainting. If these symptoms are present, call INFO-SANTÉ at 8-1-1 or speak to a health professional. If you have fever in addition to these symptoms, you may have heatstroke, which is a medical emergency. In this case, call 9-1-1 for help.

It is strongly recommended to:

  • drink a lot of water without waiting to be thirsty;
  • cool down by taking a shower or bath in cool water;
  • spend some time in a cool and preferably air-conditioned place, where possible;
  • reduce your level of physical exertion, particularly for those working outdoors;
  • wear light clothing.

>>  Consult Santé Montréal’s website page for more information


Smog is a toxic mixture of gases and particles that can often be seen in the air as haze. It is associated with several adverse environmental and health effects such as eye and respiratory irritation; coughing; aggravation of symptoms in people with cardio-respiratory diseases such as asthma, bronchitis or emphysema; and premature deaths of adults with chronic cardio-respiratory diseases

During smog episodes, vulnerable people should avoid outdoor physical activity and reduce exposure to outdoor pollution. If you have questions about your health, call Info-Santé at 8-1-1 or contact a health professional. In case of emergency, call 9-1-1

How can we reduce smog?
You can help reduce smog and improve air quality by taking a few simple actions such as:

  • taking public transit, carpooling, walking and cycling;
  • avoiding unnecessary idling of the car engine,
  • respecting the speed limits.

>> Click here to view the Air Quality Index for the island of Montréal  (in french)

>> Click here to view the Air Quality forecast from Environment Canada

Environment Canada
Ministère de l’Environnement et de la Lutte contre les changements climatiques 
Santé Montréal