Assessment of Wildland Fire Fighter Exposure to Carbon Monoxide Using Modified Occupational Exposure Limits

Date of Award


Degree Name

Doctor of Philosophy


Interdisciplinary Health Sciences

First Advisor

Dr. Kieran Fogarty

Second Advisor

Dr. Bradley King

Third Advisor

Dr. Joseph Domitrovich

Fourth Advisor

Dr. Harold Glasser


Wildland fire, wildland firefighter, wildland fire fighting, carbon monoxide, occupational exposure, hazards


To protect workers from hazardous substances or conditions in the workplace, agencies including the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) develop and periodically revise their occupational exposure limits (OELs). When developing the OELs for carbon monoxide (CO), all organizations use a derivation of the Coburn-Forster-Kane (CFK) equation to ensure that workers’ carboxyhemoglobin levels (COHb) do not exceed 3.5–7%, or the level where harmful effects may initiate. The CFK equation takes into account numerous variables such as duration of exposure, diffusion rates in a worker’s lungs, blood volume, and barometric pressure. All current OELs were developed assuming an 8-10 hour sedentary work shift at sea level. During wildland fire suppression, many of the assumptions used to develop OELs for CO may be inaccurate for fire fighters, as they may be required to complete long, arduous work shifts at differing elevations. Previous research has indicated the need for OELs to be adjusted for wildland fire fighters during wildland fire suppression activities to ensure shift length, physical exertion level, and elevation are taken into consideration. However, this adjustment was only done in one other paper in which a high workload was assumed for all wildland land fire tasks, which may not be true. Using two different data sources from the Unites States Forest Service (USFS) and NIOSH, this study (a) systematically categorizes job tasks based on physiological variability to determine whether an adjusted OEL for CO is needed to better protect this emergency response workforce; (b) develop OEL reduction factors based on workload variability, altitude, shift length and a recommended equation constant change to produce individual fire-adjusted CO OELs and a single reduced OEL protective for all wildland fire fighters; and (c) characterizes exposure to CO based on individual fire adjusted OELs for wildland fire fighters in the western U.S. from 2009–2012 and offers recommendations to better control hazardous CO exposure.

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