Chronic Respiratory Effect and Control of Occupational Exposure of Wildland Firefighters to Smoke

Project Abstract
Unlike the sporadic exposure of the general population in wildfire prone areas, exposure of wildland
firefighters (WFFs) to WF smoke is recurrent, and has recently become more so due to the increase in the
acreage of land burned by wildfires and prescribed (managed) fires. WFFs are exposed to elevated levels of WF
smoke while working at wildland fires. The airborne concentrations of the reactive particles in WF smoke at the
fireline are at least an order of magnitude higher than the health-based air quality standards in the U.S. The
inhalation exposure of WFFs at the fireline is exacerbated because they work extended hours on multiple days
per year at the fireline. Additionally, wildland firefighting is conducted mostly without any respiratory protection,
as no respirator is currently approved for the profession. Nevertheless, knowledge about the chronic respiratory
effects of such exposure is lacking. The proposed study is designed to address NIOSH’s “Public Safety” sector,
and its “Respiratory Health” and “Cancer, Reproductive, and Cardiovascular Diseases” cross-sectors by
assessing the association between occupational WF smoke exposure and subclinical indicator of pulmonary
health impairment and cancer-related molecular changes in the respiratory airways. Therefore, the hypotheses
of the proposed study are: 1) that cumulative recurrent WF smoke exposure induces adverse long-term
respiratory effects among WFFs, and 2) that a situational use of an air purifying respirator (APR) during periods
of peak particulate exposure concentrations will reduce exposure and adverse acute physiological responses.
The first hypothesis will be tested by comparing changes in DNA methylation and gene expression in the nasal
epithelium and lung function across a three-year period between WFFs and a control group of emergency
medical technicians (EMTs) matched by age, sex and ethnicity (N = 50/group). The proposed outcomes are
disease precursors and are relevant for characterizing risk of disease that may evolve long after exposure or
retirement. The second hypothesis will be tested by comparisons of cross-shift changes in urinary biomarkers of
exposure, gene expression in the nasal epithelium, and serum pro-inflammatory cytokines among WFFs (N =
35) between occasions when they wear the APR and when they do not, while working at prescribed burns.
The objective of the proposed study is well aligned with NIOSH’s priority extramural research goals to reduce
occupational cancer and respiratory disease and exposures causing them. Following the completion of the study,
we would have determined the adverse respiratory effects of cumulative occupational exposure to WF smoke
and a practical approach to mitigate them. The envisaged outputs from the proposed research, which would
include publicly accessible results and publications, would directly inform NIOSH’s priority goal to reduce
incidence of exposure and illnesses among wildland firefighters. These outputs, which will also be made
accessible to stakeholders via a virtual workshop, will contribute to appropriate risk assessment of WF smoke
exposure, the development of exposure and risk mitigation strategies, and methods to test their effectiveness.

Grant Number: 5R01OH012224-04
NIH Institute/Center: ALLCDC
Principal Investigator: Olorunfemi Adetona