Preparing for Wildfire Smoke

Wildfire smoke has become a regular feature of the Canadian summer, and it travels further than people expect. Smoke from fires in British Columbia or Alberta can settle over the Prairies and reach Ontario and beyond. The response is simple, but it helps to know it before the sky turns orange.

Check the air quality

Use the Air Quality Health Index (AQHI) from Environment and Climate Change Canada. An AQHI of 7 or higher means high risk; at that level, sensitive groups — children, older adults, people with heart or lung conditions — should reduce or avoid exertion outdoors.

Keep the smoke out

Close windows and doors, and turn off systems that bring in outside air — HRV units, open vents. Run air conditioning on recirculate if you have it. If you use a portable air cleaner, choose one with a HEPA filter sized for the room, and keep it running.

A simple DIY filter

If you don't have an air cleaner, you can make a serviceable one: tape a MERV 13 furnace filter to the back of a box fan. It is not elegant, but it meaningfully reduces fine particles in a single room. Replace the filter when it darkens.

Masks

A well-fitted N95 or KN95 reduces particle exposure outdoors when the air is poor. Cloth and surgical masks do little against fine smoke.

When the air clears

Air out the house once the AQHI drops to low risk. Change furnace filters if they've loaded up during the event.

For active wildfire emergencies and evacuation orders, follow your provincial emergency authority and local officials — not this article.