Wildfire smoke in your home: protection and cleanup

Why it matters in Ontario

Smoke from forest fires in northern Ontario, Quebec and western Canada can travel thousands of kilometres. In recent summers it has pushed air quality in southern Ontario to very poor levels for days at a time. You do not have to be near a fire for the smoke to reach your home.

Wildfire smoke is a mix of gases and very fine particles. The fine particles are the main health concern. They are small enough to get deep into the lungs. Health Canada states that there is no known safe level of exposure to some of these pollutants, and that smoke can affect health even at low concentrations.

People at higher risk include older adults, young children, pregnant people, people who work outdoors, and anyone with a lung or heart condition.

Check the conditions

Environment and Climate Change Canada issues special air quality statements and publishes the Air Quality Health Index for communities across Ontario. Check it when smoke is forecast or you can smell or see haze.

Keeping smoke out

• Close windows and doors. If the house is hot and you have no air conditioning, stay cool is the priority. Heat can be more dangerous than smoke for some people. Go to a cooler, cleaner place such as a library or community centre if you need to.
• Set air conditioning to recirculate. Close the fresh air intake on window units and central systems where there is one.
• Turn off or reduce ventilation that draws in outdoor air for the duration. A heat recovery ventilator can be put on recirculation if it has that setting. Turn it back on afterwards.
• Use exhaust fans sparingly. Bathroom and kitchen fans and the clothes dryer push air out, and smoky air comes in to replace it.
• Seal obvious gaps round doors and windows with weatherstripping.
• Avoid adding to indoor pollution: no smoking, candles, incense or frying, and do not vacuum unless the vacuum has a HEPA filter.

Cleaning the air indoors

The furnace filter. Run the furnace fan continuously to pass air through the filter. Use the highest-rated filter your system can handle. Health Canada suggests a MERV 13 rated filter where the system allows. Higher-rated filters restrict air flow, so check with a heating technician if you are unsure. During a smoke event, filters clog quickly. Check them often.

A portable air cleaner. A unit with a true HEPA filter, sized for the room, makes a real difference. Look at the clean air delivery rate for smoke and match it to the room size. Put it in the bedroom or the room where you spend most time, keep the door closed and run it continuously.

Avoid ozone generators and air cleaners that produce ozone. Ozone is a lung irritant.

A clean room. If you cannot treat the whole house, choose one room, keep it closed, and run an air cleaner there.

After the smoke clears

1. Air out the house once the outdoor air quality has improved. Open windows and run fans.
2. Replace the furnace filter, and the filters in portable air cleaners according to the manufacturer.
3. Return the ventilation system to its normal setting.
4. Dust with damp cloths and mop hard floors. Dry dusting stirs the particles up.
5. Vacuum carpets and upholstery with a HEPA-filtered vacuum.
6. Wash bedding, curtains and clothing that smell of smoke.
7. Wipe window sills, tracks and screens, where fine ash collects.
8. Clean outdoor furniture and children’s play equipment.

For most Ontario homes affected by distant smoke, this is enough. The smell fades over a few days once the source has gone.

When the smell or residue stays

Homes closer to a fire, or exposed to heavy smoke for a long time, can have residue on surfaces, in insulation and through the heating system. Signs:

• A smoke smell that returns in warm or humid weather
• A visible film or ash on surfaces
• Discoloured filters shortly after replacement
• Irritated eyes or throat indoors

In those cases the work resembles cleaning after a house fire, though lighter:

• HEPA vacuuming and wet cleaning of all surfaces
• Cleaning of ducts and the furnace or air handler
• Cleaning or replacing soft furnishings
• Replacing attic insulation where ash has been drawn in through the vents
• Deodorising with hydroxyl generators or similar methods, after cleaning

If your home was near the fire

• Do not return until the authorities say it is safe
• Wear a well-fitted respirator, such as an N95, gloves and long sleeves when cleaning up ash. Ash is irritating and can be caustic when wet.
• Dampen ash lightly before sweeping it up. Do not use a leaf blower or a household vacuum.
• Throw out food exposed to heat, smoke or ash, and fridge and freezer contents if the power was off
• Have the water tested if you are on a well
• Photograph damage before cleaning and contact your insurer

Insurance

Damage from fire and smoke, including smoke from a wildfire, is generally covered under standard home, condo and tenant policies. Where residents are ordered to evacuate, most policies provide some coverage for additional living expenses for a limited time. Cleaning costs after light smoke from distant fires may fall below the deductible. Ask your broker how your policy would respond.

Preparing before the season

• Buy filters and a portable HEPA air cleaner before they are in short supply
• Know which room you would use as a clean room
• Check weatherstripping
• Keep a supply of any regular medication, and a plan for household members with breathing conditions
• Know where to find air quality information

More: smoke odour removal.