NIOSH Evaluates Heat-related Illnesses, Rhabdomyolysis in Firefighters

Published March 9, 2016

At the request of a fire department, NIOSH recently conducted a health hazard evaluation regarding the potential risk of rhabdomyolysis and heat-related illness in cadets and instructors participating in firefighter training courses. Rhabdomyolysis, the breakdown of muscle tissue, can be caused by overheating, overexertion, crush injury, and certain medications, supplements, or medical conditions. “When muscle cells die, their contents of electrolytes and proteins are released into the bloodstream, which can result in potentially life-threatening conditions affecting the heart and kidneys,” the HHE report states.

The training was conducted four days a week and consisted of classroom lectures as well as outdoor physical training and live fire suppression exercises in full protective gear.

During the on-site visit in August 2012, NIOSH staff conducted a four-day evaluation, provided a questionnaire to 32 participants regarding work and medical history and health symptoms, and measured the body temperature and heart rate of 22 participants. NIOSH staff also monitored fluid intake, analyzed blood markers for dehydration and muscle breakdown, measured environmental conditions and body weight before and after each training day, and asked participants about their knowledge of rhabdomyolysis.

The evaluation revealed one person with rhabdomyolysis. NIOSH also found that environmental conditions often exceeded heat stress limits, and at some point during the evaluation week, many participants met the agency’s criteria for excessive heat strain. Sixteen participants experienced muscle breakdown but did not require medical attention. The evaluation noted that in most participants, levels of markers for dehydration and muscle breakdown decreased from the beginning and end of each training day. This suggested the firefighters remained appropriately hydrated.

The evaluation found that participants had no knowledge of rhabdomyolysis and its symptoms. “Participants noted that educational information should cover what rhabdomyolysis is, signs and symptoms, diagnostic criteria, and the necessity for immediate evaluation and medical treatment to prevent permanent damage,” the report says. “Participants mentioned that materials must clearly state that without proper medical treatment, rhabdomyolysis can cause permanent disability or death.”

NIOSH recommended the employer begin scheduling physically demanding activities during cooler parts of the day and training courses during cooler months, and educating all firefighters about the signs, symptoms, and dangers of heat-related illness and rhabdomyolysis. In addition, NIOSH recommended employees learn more about the signs and symptoms of rhabdomyolysis and other heat-related illnesses, alert a supervisor immediately if the signs or symptoms occur, drink plenty of fluids and take rest breaks, and talk to their healthcare provider about increased risk for rhabdomyolysis due to the type of job performed.

For more information, view the full report.