Evaluation of Noise, Stress, and Injury Risk among Firefighters

Description: Firefighting is hazardous work, as evidenced by the high rate of injuries and illnesses among firefighters. In particular, firefighters have the potential for simultaneous exposure to high levels of noise, stress, and fatigue, and there is an emerging body of literature that suggests that these exposures may be related to injury risk. Despite the high potential for injury, studies of occupational hazards associated with firefighting often suffer from inadequate exposure assessment. Exposures to firefighting hazards are difficult work to assess in situ, due in part to the transient and unpredictable nature of these hazards, as well as to the mobile nature of firefighting work.

IFSI, along with scientists from the University of Michigan, have explored exposures to several occupational hazards among firefighters undergoing vehicle extrication training. In one study, noise levels were evaluated continuously over the duration of the firefighter training week; including training, nontraining, and sleep periods. We explored the relationships between these various exposures and injury and near-miss experience, also evaluated on a daily basis for all subjects. The results of this study demonstrated a relationship of noise to injury risk among firefighters.

Of 57 firefighters evaluated:

• 10% always used their hearing protection devices during noise exposure
• 30% never used their hearing protection devices during noise exposure

Age was associated with a slight significant increase in injury or near-miss risk. Experience demonstrated a slight decrease in injury or near miss risk.

Substantially and significantly elevated odds ratio (6.9, 95% CI 2.2-22.3) for injury or near-miss with shorter time-at-task (e.g., during the first hour of a training session).

Substantially increased odds of an injury or near-miss risk for noise levels ≥93 dBA (3.2. 95% CI 1.2-8.7)

Our models illustrate:

• Noise levels greater than and equal to 90 dBA* and less than 95 dBA are associated with a 413% increase in injury risk
• Noise levels greater than and equal to 95 dBA are associated with a 496% increase in injury risk

*A-weighted decibels are an expression of the relative loudness of sounds in air as perceived by the human ear. For example:

• 60 dBA ~normal speech
• 85 dBA ~gas-powered lawnmower
• 100 dBA ~loud as a motorcycle

Results of this research suggest that not only does hearing protection block noise and limit hearing damage, wearing hearing protection during rescue operations may also decrease the chance of an injury.

Neitzel, R. L., Long, R. N., Sun, K., Sayler, S., & von Thaden, T. L. (2015). Injury risk and noise exposure in firefighter training operations. Annals of occupational hygiene, mev088. Funding Agency: University of Michigan Center for Occupational Health and Safety Engineering

PIs: Terry von Thaden, Richard Neitzel