Release of toxic substances: What to do if you hear a warning siren

Last updated July 22, 2025
Reading time: 2 min

What steps has Montréal taken to make sure the population is safe in the event of a toxic leak or hazardous materials spill? What should you do if a factory sets off a warning siren? Find out how to react.

When companies use toxic materials, Montréal works with them to put measures in place ensuring that residents are prepared for toxic leaks, spills, fires or explosions and will be notified quickly if they occur. Responders will quickly be deployed to secure the area and tell the public what to do.

Warning siren

If there is an accident, citizens likely to be exposed will be immediately warned of the danger by an warning siren, which tells the population to take shelter quickly. The sirens are connected to the Service de sécurité incendie de Montréal and to the 911 emergency call centre.

What the siren sounds like

The siren produces a rising and descending tone that lasts for three minutes. Depending on the factory, the sound is heard within a range of 335 to 1800 metres. The siren’s range may be affected by the weather. The warning siren does not sound the same as the interior sirens of some factories in eastern Montréal. These can be heard every Tuesday around 11 a.m.

Listen to the sound of a warning siren in this video.

Take shelter

If you hear the warning siren, immediately go inside the nearest building. When there is an industrial accident, chemicals can be released in the air and form a toxic cloud.

  • Close doors and windows, and use rags to block any ventilation openings. Turn ventilation systems off to keep toxic substances out. Stay away from doors and windows.
  • Listen to the radio to know what is happening and get instructions from the authorities.
  • Leave your children in school to avoid exposing them or yourself to the toxic substance.
  • To keep lines free for emergency help, avoid using your phone unless you are calling 911 to report an emergency.

Factories

If you live near one of the nine factories, subscribe to Montréal’s Notices and Alerts. You will be notified by text or e-mail if a toxic substance is released.

Siren test

Every year, Montréal plans a siren test in collaboration with the 9 factories to raise awareness among people living nearby, make sure that all equipment is working properly and prepare all emergency responders.

List of factories

Here are the address, substance handled, predicted impact range, and potentially affected areas for each factory.

Agropur Coopérative

Adress: 333, boulevard Lebeau, Montréal
Substance : ammonia
Predicted impact range : 650 m
Potentially affected areas: Ahuntsic-Cartierville, Saint-Laurent, Ville Mont-Royal

Bœuf Mérite, Metro Richelieu

Address: 11701 Boulevard Albert-Hudon, Montréal
Substance: ammonia
Predicted impact range: 335 m
Potentially affected areas: Montréal-Nord, Rivière-des-Prairies–Pointe-aux-Trembles

Multibond - Dural

Address: 550 Avenue Marshall, Dorval 
Substance: vinyl acetate
Predicted impact range: 649 m
Potentially affected areas: Dorval

Les entreposages frigorifiques Total

Address: 7500 Rue Minicut, Montreal
Substance: ammonia
Predicted impact range: 317 m
Potentially affected areas: Anjou

La Brasserie Labatt

Address: 50 Rue Labatt, Montréal
Substance: ammonia
Predicted impact range: 1800 m
Potentially affected areas: Lachine, LaSalle

Lactalis Canada

Address: 7470 Rue Saint-Jacques, Montréal
Substance: ammonia
Predicted impact rangge: 450 m
Potentially affected areas: Côte-des-Neiges–Notre-Dame-de-Grâce, Le Sud-Ouest, Montréal-Ouest

Note: Formerly Parmalat Canada Inc.

Saputo Produits Laitiers Canada (Saint-Laurent)

Address: 2365 Chemin de la Côte-de-Liesse, Montréal 
Substance: ammonia
Predicted impact range: 1100 m
Potentially affected areas: Ahuntsic-Cartierville, Saint-Laurent, Ville de Mont-Royal

Saputo Produits Laitiers Canada (Saint-Léonard)

Address: 7750 Rue Pascal-Gagnon, Montréal
Substance: ammonia
Predicted impact range: 770 m
Potentially affected areas: Anjou, Mercier–Hochelaga-Maisonneuve, Saint-Léonard

Suncor Énergie - Sulphur Plant

Adress: 11450 Rue Cherrier, Montréal-Est
Substance: hydrogen sulfide
Predicted impact range: 1300 m
Potentially affected areas: Rivière-des-Prairies–Pointe-aux-Trembles, Montréal-Est

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