Health impacts of wildfires: Improving science and informing timely, effective emergency response

Three of the worst wildfire seasons on record in BC occurred over the past decade, with tens of thousands of people evacuated from communities at risk of fire or hazardous levels of smoke.[1] BCCDC Environmental Health Services (EHS) is developing research, surveillance, and guidelines to support a coordinated health response by physicians, public health practitioners, and emergency managers.

Research
There is clear evidence that wildfire smoke causes exacerbations of chronic lung disease,[2] but it has been challenging to demonstrate effects on cardiovascular outcomes.[3] To date we have demonstrated that, at the community level, dispensations of asthma rescue medications (salbutamol) rise rapidly during wildfire smoke events (Figure 1). Our evidence (as yet un­pub­lished) shows that increases in dispensations are associated with measured concentrations of fine partic­ulate matter (measurement of ambient fine particulate matter: PM2.5) in fire-affected communities but not in communities where high particulate matter arise from traffic and other sources. We will next evaluate associations between multiple respiratory and cardiovascular outcomes and several measures of smokiness. We are also participating in an international study on ambulance calls for out-of-hospital cardiac arrest in relation to exposure to wildfire smoke.

Surveillance
BC medical health officers have historically relied upon ad hoc surveys of physicians and pharmacists to gauge health impacts during wildfire smoke events. In response to a need for more rigorous and timely information, we have developed a near real-time surveillance system that tracks salbutamol dispensations and PM2.5 throughout the fire season. In 2012, this system detected elevations in salbutamol dispensations associated with smoke from fires in Siberia, the United States, and BC (Figure 2). Over the next 3 years we will improve the surveillance system by expanding data streams, developing better health indicators, and incorporating estimates from the BlueSky smoke forecasting system (www.bcairquality.ca/bluesky) so that the surveillance system helps to predict the health impacts of smoke epi­sodes 24 to 48 hours before they occur.

Guidelines
Physicians care for patients during smoky episodes. Public health practitioners protect populations. Both must decide which interventions to use and when to use them. We have developed a response pyramid for public health practitioners and identified key questions about interventions to mitigate wildfire smoke health effects. However, the current evidence for the effectiveness of interventions is limited. For example, a single observational study[4] supports the use of portable high-efficiency particulate air (HEPA) filters indoors to reduce symptoms among patients with chronic respiratory disease during wildfire events. Combined with studies of HEPA filtration for other air pollutants, a case can be made that such individuals would benefit from HEPA filtration during wildfire smoke events. We are reviewing the evidence and convening an international expert panel to develop guidelines for health response to wildfire smoke.

Conclusion
Across North America, wildfires are expected to increase in frequency and intensity as the global climate changes,[5] and BC forests are particularly susceptible due to the widespread mountain pine beetle infestation. Our goal is to develop research, surveillance, and guidelines to inform a coordinated health response and better protect the health of British Columbians. 
—Catherine T. Elliott, MD, MHSc
—Sarah B. Henderson, PhD
—Tom Kosatsky, MD, MPH

Acknowledgments
This work was funded in part by Health Canada.

References

1.    British Columbia Wildfire Management Branch. Current statistics. Government of British Columbia: Victoria. Accessed 24 October 2012. http://bcwildfire.ca/hprScripts/WildfireNews/Statistics.asp.
2.    Henderson SB, Johnston FH. Measures of forest fire smoke exposure and their associations with respiratory health outcomes. Curr Opin Allergy Clin Immunol 2012;12:221-227.
3.    Dennekamp M, Abramson MJ. The effects of bushfire smoke on respiratory health. Respirology 2011;16:198-209.
4.    Mott JA, Meyer P, Mannino D, et al. Wildland forest fire smoke: Health effects and intervention evaluation, Hoopa, California, 1999. West J Med 2002;176:157-162.
5.    Flannigan MD, Amiro BD, Logan KA, et al. Forest fires and climate change in the 21st century. Mitig Adapt Strat Global 2006;11:847-859.