Exposures and Cross-shift Lung Function Declines in Wildland Firefighters

Abstract

Respiratory problems are common among wildland firefighters. However, there are few studies directly linking occupational exposures to respiratory effects in this population. Our objective was to characterize wildland fire fighting occupational exposures and assess their associations with cross-shift changes in lung function. We studied 17 members of the Alpine Interagency Hotshot Crew with environmental sampling and pulmonary function testing during a large wildfire. We characterized particles by examining size distribution and mass concentration, and conducting elemental and morphological analyses. We examined associations between cross-shift lung function change and various analytes, including levoglucosan, an indicator of wood smoke from burning biomass. The levoglucosan component of the wildfire aerosol showed a predominantly bimodal size distribution: a coarse particle mode with a mass median aerodynamic diameter about 12 μm and a fine particle mode with a mass median aerodynamic diameter < 0.5 μm. Levoglucosan was found mainly in the respirable fraction and its concentration was higher for fire line construction operations than for mop-up operations. Larger cross-shift declines in forced expiratory volume in one second were associated with exposure to higher concentrations of respirable levoglucosan (p < 0.05). Paired analyses of real-time personal air sampling measurements indicated that higher carbon monoxide (CO) concentrations were correlated with higher particulate concentrations when examined by mean values, but not by individual data points. However, low CO concentrations did not provide reliable assurance of concomitantly low particulate concentrations. We conclude that inhalation of fine smoke particles is associated with acute lung function decline in some wildland firefighters. Based on short-term findings, it appears important to address possible long-term respiratory health issues for wildland firefighters. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resources: a file containing additional information on historical studies of wildland fire exposures, a file containing the daily-exposure-severity questionnaire completed by wildland firefighter participants at the end of each day, and a file containing additional details of the investigation of correlations between carbon monoxide concentrations and other measured exposure factors in the current study.]

Keywords:

• occupational lung disease
• exposure assessment
• levoglucosan

ACKNOWLEDGMENTS

The authors thank the Alpine IHC for their participation in the study. We thank the U.S. Department of the Interior, the National Park Service, and the National Interagency Fire Center for arranging for the crew's participation. The authors also thank Chuck Stanich's Incident Management Team for data collected at the Red Eagle Fire.

In addition, the authors thank the following NIOSH personnel for assistance with various aspects of protocol development, data collection at the Red Eagle Fire, data analysis, and/or manuscript preparation and review: Michael Beaty, Randy Boylstein, Robert Castellan, Kristin Cummings, Gerald Hobbs, Thomas Jefferson, Richard Kanwal, Kay Kreiss, Greg Kullman, Aleksandr Stefaniak, Brian Tift, and David Weissman.

We dedicate this article to the memory of the 19 wildland firefighters from the Granite Mountain IHC of Prescott, Arizona, who perished battling the Yarnell Hill Fire, 80 miles northwest of Phoenix, Arizona, on June 30, 2013.

The findings and conclusions in this report are those of the authors and do not necessarily represent the views of NIOSH. Mention of any company or product does not constitute endorsement by NIOSH.