Hazards and risks after wildfire

After evacuations: health impacts

Areas of wildfire activity are often at the wildland-urban interface (WUI), the intersection of infrastructure, human activity, and flammable land cover (trees, shrubs, grassland, and other vegetation). Wildfires in the WUI can be started by a weather event such as lightning strikes, or by humans.

When there is imminent danger of fire, evacuation orders are issued for populated areas. Evacuation orders differ from evacuation alerts and have a considerably more profound impact on people's physical, mental, and emotional health. An evacuation order requires residents to leave their homes immediately to avoid the high risk of a fire. An evacuation alert, on the other hand, means a threat is potentially impending, and residents should be ready to leave on short notice, but there is a bit more flexibility in terms of timing.

Because they endanger lives and cause extensive damage, wildfires—and subsequent evacuations, which disrupt daily life—have an undeniable impact on physical, mental, and emotional health. Evacuees can experience mental health impacts such as

  • insomnia
  • depression
  • substance use disorder
  • generalized anxiety disorder (GAD)
  • post-traumatic stress disorder (PTSD)

These conditions can be exacerbated in individuals with pre-existing mental health conditions.

If you or someone you know is struggling, see the list of suggested mental health and community supports.

Air quality: smoke, ash, and other pollutants

Those living or working in close proximity to wildfire activity, evacuees, emergency responders, frontline workers, and outdoor workers have the greatest exposure to wildfire smoke. However, wildfire smoke can travel great distances and can therefore affect air quality for extended periods People across Canada can conceivably be exposed and affected. Fire risk remains high to very high across Alberta, and the Air Quality Health Index, which assigns a number from 1 to 10 to indicate the level of health risk associated with local air quality, is similarly moderate to high in most areas. (The higher the number, the higher the level of health risk. Learn more.)

During episodes of poor air quality, such as wildfire smoke events, access to air quality information is important in helping you make informed decisions to protect your health.

Wildfire smoke consists primarily of a mix of particulate matter (PM), ozone, ammonia, carbon monoxide, nitrogen dioxide, polycyclic aromatic hydrocarbons, volatile organic compounds (VOCs), water vapour, and trace metals. Not only can exposure occur outdoors, but it can also occur indoors when wildfire smoke enters homes through windows, doors, and vent openings.

It's important that the air indoors is as clean as possible, especially if you have to stay inside due to wildfire smoke events. Protect your indoor air from wildfire smoke by

  • keeping windows and doors closed as much as possible. When there's an extreme heat event occurring with poor air quality, prioritize keeping cool
  • using a clean, good quality air filter in your ventilation system based on the manufacturer's recommendations
  • using a certified portable air cleaner that can filter fine particles
  • changing the filters of your ventilation system and portable air cleaner regularly during wildfire smoke events
    (Clogged filters aren't effective at removing smoke.)
  • limiting the use of exhaust fans, such as bathroom fans

According to the Public Health Agency of Canada, there is no safe level of exposure for some of the pollutants associated with wildfire smoke, and, as smoke levels increase, health impacts also increase. Fine particles (PM2.5) represent the main health risk from wildfire smoke. These particles, airborne particulate matter with a mass median diameter less than 2.5 micrometres (µm), aren't visible to the human eye and have been linked to a wide range of health effects. They can be inhaled into the lungs and can enter the bloodstream.

Symptoms of exposure to wildfire smoke include

  • headache
  • mild cough
  • production of mucus
  • eye, nose, sinus, and throat irritation

In many cases, you can manage these symptoms without medical intervention. More serious but less common symptoms of smoke exposure include

  • dizziness
  • wheezing
  • chest pain
  • severe cough
  • asthma attacks
  • heart palpitations
  • shortness of breath

Short-term exposure to wildfire smoke or wildfire particulate matter has been strongly associated with

  • acute bronchitis
  • all-cause mortality
  • increases in respiratory emergency room visits and hospitalizations
  • exacerbation of chronic respiratory conditions such as asthma, emphysema, and chronic obstructive pulmonary disease

If you experience any of these symptoms, talk to a health care provider or seek urgent medical attention.

Less commonly, exposure to wildfire smoke can lead to:

  • stroke
  • heart attack
  • premature death
  • reproductive and developmental effects, such as low birth weight

Improving indoor air quality

Filtering indoor air can reduce some air pollutants in your home, but air cleaning is rarely effective on its own. Consider using it alongside

  • improving ventilation
  • reducing contaminants at the source

Air purifiers (also known as portable air cleaners), particularly high-efficiency particle air (HEPA) filters and electrostatic precipitators, can reduce levels of some air contaminants. HEPA filters collect particle pollutants with a fine filter. Electrostatic precipitators, on the other hand, collect pollutants with electrostatic energy, which causes pollutants to stick to the filter.

Some air cleaners with electrostatic precipitators may also produce low levels of ozone, which can irritate the lungs. Ozone generators are sometimes marketed as air cleaners, but they're not recommended for use in homes.

Air cleaners can be effective in removing particles, although most do not remove gases.

Hazards

Once an evacuation order is lifted, evacuees likely have myriad questions not only about re-entry, but also about what awaits them.

After a wildfire near your home, your home and/or property may be affected by smoke, soot, and ash.

Do not go back into any areas that were heavily damaged or destroyed by wildfire until the local authorities allow you to return.

In addition to air quality, there are other hazards and risk of which you should be aware. They're outlined in the following sections.

Hot spots and ash pits

Use caution when entering burned areas because there may still be hazards, including hot spots and ash pits, which can flare up without warning.

An ash pit is a hole in the ground filled with ash, possibly containing hot embers beneath. It's one of the many hazards faced by those fighting wildfires, and it's also a danger to residents and pets returning after a wildfire has gone out. Watch for ash pits, and mark them for safety. Be sure to warn family and neighbours to keep clear of the pits also. Keep a close eye on animals, and keep them under your direct control: hidden embers and hot spots could burn your pets’ paws or hooves.

Fallen timber, damaged trees, or unstable structures

Ensure your home is secured against further damage. Check for damaged trees or external buildings that may have become
unstable. If you rent, the landlord or property manager should do this. If you own the home, you should board up broken windows
and smashed doors, and cover holes in walls and in the roof. You can also call a contractor to do this.

Damaged or fallen power lines

Avoid damaged or fallen power lines. Downed power lines can be extremely dangerous. Contacting an energized line can seriously injure or kill you. If you see a downed power line, stay at least 10 metres away, call ATCO’s emergency outage line 1-800-668-5506, and keep everyone safe from the area.

Spoiled food or unsafe water

Ensure your food and water are safe.

Discard any food that may have been exposed to heat, smoke, or soot, and do not use water that may be contaminated.

Perishable foods, foods packaged in cardboard or plastic, or any foods or medicines directly exposed to heat, smoke, fumes or water should be discarded. Discard all food in glass jars, as there is a high chance that the seal was broken by exposure to heat.
Similarly with food in metal cans, the integrity of the can may have been affected by exposure to heat.

Don’t eat fruits and vegetables that were growing in your garden during the fire. They are likely affected by smoke. Garden produce/plants may be impacted by fire retardants. Dispose of garden produce potentially impacted by fire retardants.  

Never use water you think may be contaminated to wash dishes, brush teeth, prepare food, wash hands, make ice, or prepare baby formula.

A boil water advisory is currently in effect for certain parts of the Jasper townsite. Areas within the Town of Jasper in which the boil water advisory has been lifted and where the advisory remains in effect are referenced in this map. Details and instructions will be available prior to re-entry on August 16.

Residents and businesses in the Town of Jasper where the boil water advisory has been lifted can return to normal water consumption practices; boiling is no longer required.

AHS Environmental Public Health officers will continue to monitor the situation, including sampling and testing of the drinking water to ensure it is safe for consumption, prior to lifting the advisory for remaining areas within the community.

Before moving back into your home, ensure that

  • adequate toilet facilities are available.
  • every room that was affected by the fire has been cleaned, disinfected and dried
  • all affected dishes, utensils and glasses have been thoroughly washed and disinfected

Residents with health concerns can contact Health Link to speak with a registered nurse 24 hours a day, seven days a week, toll-free at 811.

Hazardous materials

Contact your municipality or Alberta Health to find out how to dispose of hazardous materials such as solvents, garden chemicals, and home cleaning products that have been soaked or that show signs of water damage.

Volatile organic compounds

Volatile organic compounds (VOCs) form a large group of chemicals commonly found in both indoor and outdoor air. As such, they can affect air quality. While some VOCs give off distinctive odours at higher levels, they may be present even if you can't smell them. Depending which VOCs are present, their levels, and how long you're exposed, VOCs in indoor air may affect your health and cause

  • fatigue
  • nausea
  • dizziness
  • headaches
  • breathing problems
  • irritation of the eyes, nose and throat

Mould

Poor indoor air quality can often be attributed to excess moisture. This is because moisture promotes the growth of both dust mites and mould. The presence of mould has been linked to such health symptoms as

  • coughing
  • wheezing
  • allergic reactions
  • shortness of breath
  • production of mucus
  • eye, nose, and throat irritation
  • worsening of asthma symptoms

Some airborne moulds can cause severe lung infections in people with very weakened immune systems (e.g., transplant patients or individuals with leukemia or AIDS).

In most cases, there's no need to measure the concentration of mould in indoor air, simply find and fix the moisture and mould problems. To prevent mould, fix any moisture problems right away and control humidity levels in your home.

Mould often looks like a stain, comes in a variety of colours, and typically has a musty odour. In some cases, however, it may not be be easy to spot. Check for it anywhere that's damp, especially where water damage has happened. Inspect your home for visible signs of mould or areas with too much moisture. When conducting a visual mould assessment,

  • Take precautions to protect your health: wear gloves and a N-95 mask. 
  • Look for stains or discolouration on floors, walls, window panes, fabrics, upholstery, and carpets.
  • Assess the extent of mould growth and the materials affected.  

Any patch of mould larger than a bath towel (10 ft² or 1 m²) is cause for concern, particularly if there are three or more patches of this size or larger. If this is true of your home, consider hiring a professional to clean it up, especially if there is a large amount of mould or if the mould keeps coming back after you clean it.

To remove mould,

  • Take precautions to protect your health: wear gloves and a N-95 mask. 
  • Remove mouldy materials in a sealed plastic bag. 
  • Remove and dispose all affected soft materials (e.g., carpet, upholstery, fabrics, etc.)
  • Remove and dispose water-affected soft materials and drywall. Water-affected materials can grow mould.  
  • Dispose of the bagged mould waste appropriately.
  • Assess items that can be saved, including
    • surfaces that did not absorb water 
    • fabrics that can be dry cleaned or laundered, and then bleached 

To clean mould,

  • Clean and disinfect items that can be saved.
  • Clean all surfaces around the mould-affected areas with soap and warm water.
  • Once you have finished, sanitize all surfaces using a mild bleach solution (one tablespoon (15 mL) bleach to one gallon (4 L) water. 
  • Dry wet items as soon as possible. 
  • Use a dehumidifier to remove excess moisture. 
  • Open windows and use fans to circulate air. 

More tips and resources

Additional tips and information can be found on the following websites and in the following booklets and publications:

References

Bruce, Graeme. CBC News. Tracking wildfires in Canada. (Accessed August 16, 2024.)
Canadian Red Cross. Wildfires: Before, During & After. (Accessed August 16, 2024.)
Health Canada. Improve air quality in your home. (Accessed August 16, 2024.)
Health Canada. Mould. (Accessed August 16, 2024.)
Health Canada. Volatile organic compounds. (Accessed August 16, 2024.)
Health Canada. Wildfire smoke and your health. (Accessed August 16, 2024.)
Public Health Agency of Canada. Public Health Risk Profile: Wildfires in Canada, 2023. (Accessed August 16, 2024.)