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Wildland Fire Smoke Health Effects on Wildland Firefighters and the Public - Final Report to the Joint Fire Science Program

Author(s): Joe Domitrovich, George Broyles, Roger D. Ottmar, Timothy E. Reinhardt, Luke P. Naeher, Michael T. Kleinman, Kathleen M. Navarro, Christopher E. Mackay, Olorunfemi Adetona
Year Published: 2017
Description:

Wildland fire smoke is a complex mixture of air contaminants that have the potential cause adverse health effects. Individuals can be exposed occupationally if they work as wildland firefighters or public exposure from ambient air that is contaminated with smoke from a nearby or distant wildland fire. Previous studies of public exposure to smoke have suggested that wildland fire smoke can cause adverse respiratory health effects and possibly increased mortality and cardiovascular health effects. What the research means for healthy workers is less clear. For example, in wildland firefighters, minor decrements in lung function may be at least partially reversible after periods of recovery (no exposure), but even temporary clinically significant adverse effects from occupational exposures are unacceptable outcomes. This work combines a comprehensive literature review with extensive smoke exposure concentration data for wildland firefighters to estimate health risks specific to wildland fire smoke. First, we conducted a literature review to identify smoke components that present the highest health hazard potential, the mechanisms of their toxicity, and reviewed epidemiological studies to identify the current gaps in knowledge about the health impacts of wildland fire smoke exposure for firefighters and the public. Next, we examined wildland firefighter exposures, explored predictors of smoke exposures to determine factors influencing smoke exposure for wildland firefighters and estimated exposure to air pollutants using carbon monoxide (CO) as an indicator pollutant. Lastly, we estimated disease risk in wildland firefighters for exposure to particulate matter from smoke using firefighter specific breathing rates with existing exposure response relationship information for risk of lung cancer, ischemic heart disease and cardiovascular disease from cigarette smoking, which produces particulate matter with a similar size range. From the literature review, we found that respiratory events measured in time series studies as incidences of disease-caused mortality, hospital admissions, emergency room visits and symptoms in asthma and chronic obstructive pulmonary disease patients are the health effects that are most commonly associated with public exposure to wildland fire smoke. A few recent studies have also determined associations between acute wildland fire smoke exposure and cardiovascular health end-points. From this review, we concluded that there remains a need for research on acute and longer term effects of wildland fire smoke exposure. The health effects of acute exposures beyond susceptible populations and the effects of chronic exposures experienced by the wildland firefighter are largely unknown. Longitudinal studies of wildland firefighters during and/or after their firefighting career could help elucidate some of the unknown health impacts of cumulative exposure to wildland fire smoke, establish occupational exposure limits, and help determine the types of exposure controls that may be applicable to the occupation. We found that among 83 firefighters at prescribed burns, and 417 at project wildfires, the Occupational Safety and Health Administration (OSHA) 8-hour exposure level of 50 ppm for CO was exceeded 3.5 percent of the time at prescribed fires and 5.6 percent of the time at project fires. Adjustments recommended for altitude, work rate and duration of exposure would increase these percentages. We identified that crew type, main work task and duration, and downwind position from the fire were factors that influenced exposure to CO and respirable particulate matter, but only main task and duration were important predictors for respirable crystalline silica exposure. Linear regression results indicated that CO measurement is a reasonably useful real-time gauge of the inhalation hazard from smoke-derived particulate matter. The exposure data also found that respirable crystalline silica was a soil-derived hazard that exceeded shift-average OSHA Permissible Exposure Limits from 6.7% to as much as 28% of the time, depending on incident type. Using epidemiology studies to understand the exposure-response relationship for PM, we found that firefighters were at an increased risk for long-term health effects from smoke exposure. The risk for lung cancer mortality increases nearly linearly with exposures over time and is more strongly influenced by exposure duration than are the risks of death from cardiovascular or ischemic heart disease. On the other hand, the risk of cardiovascular mortality rises steeply for doses in the range we estimated for firefighter exposures but flattens out at higher exposures to PM. The data presented in this paper clearly identify the crews and activities most likely to exceed occupational exposure limits and firefighters may have a an increased health risk from smoke exposures.

Citation: Domitrovich, Joe; Broyles, George; Ottmar, Roger D.; Reinhardt, Timothy E.; Naeher, Luke P.; Kleinman, Michael T.; Navarro, Kathleen M.; Mackay, Christopher E.; Adetona, Olorunfemi. 2017. Wildland Fire Smoke Health Effects on Wildland Firefighters and the Public. Joint Fire Science Project 13-1-02-14. Missoula, MT: US Forest Service. 43 p.
Topic(s): Fire Effects, Ecological - First Order, Emissions, Human Dimensions of Fire Management, Human Factors of Firefighter Safety, Smoke & Air Quality, Smoke Emissions
Ecosystem(s): None
Document Type: Technical Report or White Paper
NRFSN number: 17009
FRAMES RCS number: 24570
Record updated: Mar 7, 2018