Smoke

Decades of extreme fire suppression and the effects of climate change are contributing to more frequent and severe wildfires – increasingly exposing British Columbians to health concerns from breathing smoke.

This trend is expected to continue, making it imperative that we learn how to look at proactive ways to mitigate wildfires and their health impacts.

Smoke and Human Health Impacts

The air we breathe indoors and outdoors contains particle pollution created by everyday activities like driving cars, manufacturing, and using wood stoves and fireplaces. During a wildfire, concentrations of particles can significantly worsen air quality.

Particles from smoke can include a variety of gaseous air pollutants. The principal public health threat is from fine and coarse particulate matter (PM2.5 and PM10, respectively) suspended in the atmosphere and potentially inhaled into the lungs.

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XExposure to smoke, particularly PM2.5, may cause serious health effects, including heart and lung problems, and can make existing health conditions worse. To view air quality information and reports on the health risks posed by a mixture of pollutants, visit the Air Quality Health Index. For more information and resources on air quality, the health impacts of wildfire smoke and ways to prepare for wildfire season, visit the BC Center for Disease Control.

How prescribed fire can help reduce wildfire impacts

According to a new report released by the American Lung Association, prescribed burning can help reduce the impact on air quality and human health from wildfire smoke.

The report shows that historical fire suppression efforts are insufficient for long-term fire management, while proactive wildfire reduction activities, such as cultural burning and prescribed fire can help to mitigate large-scale wildfires and their negative impacts on air quality, health, and safety.

While more research is needed to evaluate the comparative risks of prescribed fire vs. wildfire smoke, implementing prescribed burns under the right conditions can mitigate the negative impacts of large-scale fires. The report also found that although increasing burning activities may contribute to local air quality impacts, prescribed fires are implemented with strategies to minimize harmful smoke exposure.

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XThe difference is that wildfire conditions cannot be predicted or controlled. These fires often result in the consumption of trees, vegetation and other organic materials, which produce larger amounts of smoke that can affect the air quality for thousands of miles. In contrast, prescribed fires are carefully planned and implemented according to an approved burn plan, which indicates specific weather and fuel moisture conditions that help reduce smoke impacts.

How burn operators mitigate smoke

Smoke is an important consideration when planning a prescribed fire. In addition to reducing visibility, smoke can affect firefighters and public health and safety. These concerns are addressed by ensuring prescribed fires are implemented under conditions that limit unintended smoke impacts. Smoke management requirements and strategies are components of every prescribed fire burn plan, generally falling into one of three categories:

Avoidance

This involves planning prescribed burns with weather conditions that make intrusions of smoke into smoke-sensitive areas unlikely.

Dilution

This strategy can help reduce smoke concentration by diluting smoke through a greater volume of air by scheduling the burn during favourable conditions or burning at slower rates.

Emission

This involves using emissions factors where wildland fire managers employ a range of techniques to limit sources of long-term emissions, like smoldering.

Smoke management strategies

Here are some of the smoke management strategies and considerations included in a burn plan:

  • Prescribed fires are typically implemented in the spring or fall when fire danger ratings are lower, producing less smoke than an unplanned wildfire that usually occurs under warmer and drier conditions consuming more fuel. (Emission)
  • Strategies for minimizing the impacts of smoke are identified and captured in the burn plan, including venting heights and indices, transport winds aloft, wind direction, and ensuring fuel indices contain as little moisture as possible. (Dilution, Emission)
  • Fire weather forecasts are obtained in consultation with a BC Wildfire Service regional fire weather forecaster to determine atmospheric stability, wind and forecasted weather conditions before implementing a prescribed fire. During implementation, operations may be suspended if smoke does not disperse as forecasted. (Avoidance, Dilution)
  • Under the Open Burning Smoke Control Regulation, British Columbia is divided into three smoke sensitivity zones that are considered before implementing any prescribed fire. (Avoidance)
  • Factors that are unique to each site, like topography, elevation, atmospheric conditions, fuel type/loading and human exposure, are factored into smoke management planning. (Avoidance)
  • The time of ignition (daytime or night-time) may be factored into a burn plan to ensure smoke is better dispersed at the ground level and in the upper atmosphere. (Avoidance, Dilution)
  • Onsite weather readings are conducted before and during prescribed burns to ensure weather conditions and fuel moisture levels are favourable for minimizing the amount of smoke produced. (Emission)
  • Atmospheric conditions are considered before igniting a prescribed fire. In a stable atmosphere, smoke tends to hang near the ground, whereas in an unstable atmosphere, smoke is carried aloft. Cloud types are helpful onsite indicators when considering atmospheric conditions. (Dilution, Emission)
  • Wind speed and direction are important considerations for smoke dispersion. More wind can help disperse a plume; however, strong surface wind speeds may cause a plume to lay-down near the surface and limit vertical dispersion. (Dilution)
  • If there is a concern that smoke could impact traffic, a separate traffic safety plan utilizing signage, flaggers and pilot vehicles would be implemented in the impacted areas. (Impact Mitigation)
  • The amount of smoke already in the atmosphere from wildfires is factored into the burn plan before implementation of a prescribed fire project. (Dilution)


How to protect yourself from smoke

There are several resources available to educate and protect yourself from smoke:

  1. Learn more about the health impacts of wildfire smoke & ways to prepare for the wildfire season by visiting the BC Center for Disease Control.
  2. Familiarize yourself with the BC Smoke Sensitivity Zones/Maps
  3. Review the venting conditions for your area by visiting the BC Venting Index Map and Ventilation Index Interactive Map.
  4. Identify the best areas and opportunities for good air quality through the BC Air Quality Health Index.

Prescribed fire case Studies

Owl Creek Cultural Burn

Filmed in July 2022, the Owl Creek Cultural Burn was implemented by Lil’wat Nation with support from BC Wildfire Service in Mount Currie on Lil’wat Nation Traditional Territory just outside of Pemberton, BC.

See Case Study

River Valley Prescribed Fire Case Study

Nation Traditional Territory outside of Pemberton, BC with the objective of protecting the community. The case study provides an overview of the three phases of a prescribed fire lifecycle and shows the value of partner collaboration when implementing a project of this scale.

See Case Study