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

Last updated October 16, 2023
Reading time: 1 min

In Montréal, ten factories have a warning siren that will go off if there is a major industrial accident. What should you do if you hear a warning siren? Follow these instructions to protect yourself.

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.

What the siren sounds like

When an alarm goes off, 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 1860 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.

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

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