B.C. Air Quality

How Forest Fires Affect Air Quality

Forest fires are the second-largest source of PM2.5 from wood smoke in the province (second to open-burning sources). They can have significant impacts on local air quality, visibility and human health. Emissions from forest fires can travel large distances, affecting air quality and human health far from the originating fires. These emissions include:

  • particulate matter;
  • carbon monoxide;
  • atmospheric mercury;
  • ozone-forming chemicals; and
  • volatile organic compounds.

The fire season in 2003 highlights the significant impact forest fires can have on the health and safety of communities. The Firestorm Provincial Review attributed the severity of the fires to fire-suppression practices and policies of the past, and resultant fuel build up.

The report's recommendations include using prescribed burning as a fuel-management tool. It recommends requiring all slash in or beside a wildland urban interface to be removed, treated or burned on site — to decrease the surface-fuel hazard.

In other words, planned and controlled burning that can expose people to wood-smoke pollution in small amounts is far more desirable than uncontrolled wildfires that can greatly impact air quality for longer periods of time, and elevate the risk to human health and safety. Burning to reduce fuel build up for community protection is important. However, in many cases, fuel management can be accomplished through other means. Burning should be limited so as to minimize people's exposure to wood smoke.

With respect to how forest fires affect human health, a report by the British Columbia Centre for Disease Control, entitled Wood smoke, forest fires, and PM2.5 in British Columbia, states:

"The Central Okanagan region had high levels of PM2.5 between mid-August and mid-September, 2003, due to forest fires. To see whether the forest fires had any detectable effect on the health of Kelowna residents, billings for physician services submitted to the Medical Services Plan (MSP) were reviewed. Patient use of physician services for the period 1 June 2003 to 12 October 2003 was compared with average levels for the same periods from 1993 to 2002. While no increase in billings was seen for circulatory conditions, a significant increase for respiratory conditions was found. One week following the peak in PM2.5 caused by forest fires, there was a 46% increase in patient visits for respiratory conditions compared with the mean rate from the same week in the previous 10 years. Four weeks following the peak in PM2.5, a 78% increase was evident."

It should be noted that the report also says: "Although forest fires present the potential for elevated exposure to PM2.5, they are relatively infrequent events compared to residential woodburning during winter months."

The proceedings of the Smoke Forecasting Workshop 2007 contain a number of articles related to the air quality effects of forest fires. You may also be interested in Forest Fires and Respiratory Health Fact Sheet (American Lung Association) and FireSmoke (University of British Columbia).

For information on how smoke affects our health, see Air Quality and Your Health.


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