Wildfire Smoke Exposure – UPDATE

Earlier this year, we watched the bushfire situation in Australia unfold, and now we observe major wildfires along the Pacific coast of the United States with heavy hearts. In Canada, it’s estimated that approximately 8,000 wildfires happen each year. Many of the fires occur in the densely forested areas during dry conditions and can devastate communities, destroy buildings and infrastructure, and claim human lives.

According to National Wildfire Situation Report, 2020 has been one Canada’s quietest years for forest fires since the 1990s. However, the western provinces were not able to completely escape them this year as significant fire events have occurred in the Penticton and Vancouver areas. In addition, this region is currently affected by smoke from the massive wildfires that are burning in California, Oregon, and Washington states.

A similar situation occurred last summer with respirable particulate matter measured in Edmonton 10-30 times higher than the national guidelines.  This was due to wildfires burning in central and northern Alberta many hundreds of kilometers away.

According to British Columbia’s Air Quality Health Index readings, the levels in the Metro Vancouver area, the Fraser Valley, Nanaimo and southern Vancouver Island are currently listed at 10+, or “very high risk”, as a consequence of the current US wildfires.

Wildfire smoke, which generally contains large amounts of respirable particulate matter, has travelled up the west coast and impacted the air quality and visibility in many western communities. Once combustion by-products/smoke are high in the atmosphere, they can be transported great distances.  Sadly, fine particles that are most damaging to human health are easily able to travel large distances and are more difficult to protect against.

To protect against exposure to ambient smoke and soot from wildfires, it is typically recommended to remain indoors and rely on the building envelope to prevent unfiltered air from entering an indoor space and the filtration of your home’s HVAC system to remove the majority of particles in the indoor air. However, with the current COVID-19 pandemic, there is desire – especially in Canada as winter approaches – to maximize time spent outdoors and to encourage high rates of fresh air ventilation to indoor spaces. Measures community members have already taken to protect themselves from the COVID-19 virus such as wearing masks and frequently cleaning surfaces will also help to reduce exposure to harmful atmospheric condition resulting from wildfires.

In addition to these measures, we recommend implementing these proactive steps to reduce your exposure to airborne contaminants inside your home and/or workplace during the pandemic and episodes of poor outdoor air quality:

  1. Upgrading and improving the filters in your HVAC system to MERV 13 filters if you have a sufficiently powerful fan;
  2. Set ventilation systems to recirculate; and
  3. Consider creating a Clean Air Shelter (CAS) in one or more of the rooms in your home/workspace:
    -Maintain tight sealing windows and doors
    -Using a portable HEPA air filtration machines to remove fine particulate
    -Include carbon-based air filters to remove odours and other misc. contaminants

Take care using electronic air filtration devices as some of these produce ozone as a by-product which can be hazardous to furniture, fixtures and human health.

If it is necessary to go outdoors during an extreme air pollution episode, it is advised that an N95 or P100 particulate respirator be worn, though these may be difficult to obtain due to the high demand in the medical community related to COVID-19 needs.

COVID-19 precautions include ventilation of indoor spaces with as much outside air as possible. However, there is a trade-off as employers may be required to reduce outside air supply to indoor spaces for Occupational Health and Safety reasons related to high risk Air Quality Health Index readings. Therefore, when you enter indoor public spaces, such as grocery stores, during extreme air pollution episodes, be sure to practice or exceed COVID-19 Public Health safety measures to help protect yourself and others.

There are resources available for those looking for more specific guidance, including an excellent summary from the EPA on how people can help protect themselves if found in such a situation as well as guidance from ASHRAE regarding ventilation systems.

Stay tuned for part 2 which will address this issue from an Occupational Health and Safety perspective