Limitations of Research on Health Effects of Fire

Scientific research on the human health consequences of forest fires is relatively new and contains numerous limitations (research on the composition of biomass smoke only began around 1970 [Ward and Hardy 1991]). Most research on smoke effects investigates single constituents of smoke such as aldehydes, PAHs, particulate matter, hydrocarbons, inorganic gases, and trace gases. Much of this research tests the effects of these pollutants on human health from sources other than forest fires such as automobiles and industrial production. Also, most studies look at short-term health outcomes, while very few studies of the long-term health effects of exposure to biomass smoke exist. Another limitation of research is that smoke itself is spatially variable and smoke has variable health impacts on local populations. But, our understanding of the health effects of biomass smoke is increasing due to a growing interest in this subject among the general public, within the scientific community, and among policy makers and land managers.

It is unclear whether the net effects of forest fires on human health are adverse, beneficial, or inconsequential. Most investigations of this topic attempt to document adverse effects with little or no attention to beneficial effects. Yet, beneficial changes in interpersonal relations, and in socio-cultural, economic, and political systems can occur as a consequence of forest fires. Thissections in the fire encyclopediarelated to the health effects of fire focus on research that demonstrates the adverse biophysical effects of biomass smokesince the larger portion of researchers approach the topic from this angle. Some researchers ask, “What are the harmful effects of x constituent of biomass smoke?” or “How did y fire impact the health of local people?” If they have not been able to demonstrate significant negative impacts, researchers conclude that the effects of forest fires are inconsequential.

Research from a variety of disciplines is used to estimate the health impacts of forest fires. Epidemiologic studies on the health consequences of indoor air pollution created by the burning of biomass fuel for cooking, heating, and light offer insight into the health impacts of biomass smoke created by forest fires (Larson and Koenig 1994). Studies in the field of animal toxicology provide information about the impacts of biomass smoke on the health of animals that can be extrapolated with caution to expand our knowledge of human health impacts. In animal toxicologyresearch on the effects of the smoke from burning pine on dogs, researchers observed changes in epithelial cells that predict the development of pulmonary hypertension which increases heart attack risks (Larson and Koenig 1994). Damages to tracheobronchial epithelial cells appear in rabbits that breathe smoke from burning white pine (Larson and Koenig 1994). Enzymatic changes predicting the development of pulmonary hypertension occurred in dogs that were forced to breathe highly concentrated smoke from burning pine (Larson and Koenig 1994). Significant changes in macrophages occurred in rabbits that were forced to breath smoke from burning Douglas fir (Larson and Koenig 1994). In the field of anthropology, researchers are interested in contemporary burning practices of communities around the world (e.g, Vayda 1999). Anthropologists of Native North America have reconstructed burning practices of prehistoric and early-historic communities within the context of overall ecological management regimes (e.g., Krech 1999).

Overall, opinions on the health impacts of smoke from forest fires are equivocal: some authors have found evidence that biomass smoke is injurious (e.g., Grant 1988), other authors have found evidence that biomass smoke does not have significant adverse health effects (McMahon 1999; Van Lear and Waldrop 1989). Some researchers argue that public health risks from biomass smoke are minimal because air pollution stemming from forest fires rarely if ever exceeds limits set by governmental and non-governmental agencies (McMahon 1999). Other authors argue that serious damages to public health, including chronic disease and premature death, occur even when air pollution levels are below the limits set by governmental agencies (EPA 1998; Schwartz and others 1993).

The ambiguity in the research literature is due both to the lack of and inherent difficulties with research on this topic. Research on this topic should continue in order to fill some of the voids in existing knowledge. There is a need for more research that investigates individuals and communities in areas where wildland and prescribed burns occur. These studies ought to consider smoke as people actually encounter it during forest fires; that is, a whole, complex mixture of interacting chemicals and particles. Among the current literature, there is a lack of information about the perceptions of individuals. Future research on the health impacts of fire could be improved by using ethnographic methods. Research would be much more textured if it included accounts of the ways that individuals interpret their experiences with forest fires. Each facet of the health-fire relationship ought to be contextualized in a particular fire event and a particular environment. To be accurate, future research ought to coordinate the characteristics of particular fires with local environmental traits, in addition to local human conditions.

Our present understanding is somewhat reductionistic and gives disproportionate attention to the physiological effects of fire. A more holistic view of the health impacts of forest fires would investigate psychological, social, cultural, economic, and political consequences as well. Future investigations should pay more attention to links between physiological and other types of effects of forest fires on people (e.g., psychological, economic, cultural). A holistic presentation requires both scaling up by contextualizing biomedical and chemical analyses and scaling down by adding fine-grained understandings of individuals’ lived experiences. In the future, researchers could expand their methodological repertoire and use integrative models to better understand relationships between people and fire.