Two new studies look at role of personality and work demands in health and safety on the job

July 15, 2001

WASHINGTON -- Two new studies find that personality and job complexity can influence the health and safety of industrial workers and firefighters. The findings appear in the July issue of the Journal of Occupational Health Psychology, a journal of the American Psychological Association (APA).

In the first study, researchers examined injury data from 171 firefighters from a major midwestern U.S. city over a 12-year period and found that certain personality traits, including introversion, were significantly related to higher injury rates on the job. Also, female firefighters reported 33 percent more injuries than male firefighters in the study by Hui Liao, B.A., Richard D. Arvey, Ph.D., and Richard J. Butler, Ph.D., of the University of Minnesota and Steven M. Nutting, M.A., of the City of Minneapolis.

The researchers say the higher injury rate for female fighters may be due to cultural influences. "Within male firefighters, there may be a strong cultural norm for not reporting minor injuries because it may be viewed as a sign of weakness," say the authors. "For female firefighters, this norm might be different."

The finding that personality traits like introversion were related to higher injury rates may be the result of introverts being less likely to call for assistance. "Firefighters perform more safely and effectively if they cooperate well with each other," said the researchers. "Therefore, those who are more reluctant to interact with team members may seek less help from coworkers during an emergency, thereby exposing themselves to greater risks." Also related to personality characteristics, the study found that firefighters who tended to ignore safety rules and regulations not only had accidents more frequently but also suffered more severe injuries, while conscientious firefighters performed more safely on the job.

The researchers also examined the amount of time spent off the job recovery from injuries. Older firefighters took longer to recover from injuries than did younger firefighters, and those with less fire fighting experience suffered more severe injuries than those with more experience. However, what surprised the researchers was the finding that after an injury, married female firefighters returned to work the earliest, followed by unmarried male, unmarried female and married male firefighters. Fire companies may assign working mothers to the least risky tasks when fighting a fire, say the authors, making them less likely to experience certain types of severe injuries. Another explanation, according to the researchers, is that married female firefighters may be more cautious than unmarried female firefighters and thereby less likely to be exposed to certain injury risks.

The researchers say the study results have implications for other occupations that involve life-threatening risks that may lead to effective workplace safety interventions and a reduction in injury-related costs.

In the second study, chronic exposure to loud industrial noise was found to increase blood pressure overtime and to reduce job satisfaction, especially for those with complex jobs. On the other hand, for workers in simple jobs (those jobs involving less task complexity and variety) being exposed to moderate levels of ambient noise was found to be beneficial.

Study authors Samuel Melamed, Ph.D., and Paul Froom, M.D., of the National Institute of Occupational and Environmental Health in Israel and Yitzhak Fried, Ph.D., of Wayne State University investigated the effects of noise exposure on changes in blood pressure levels and job satisfaction of 807 blue and white collar workers from 21 industrial plants. The workers (ages 22-62 years old) were followed for a two and four year period. The results show that workers who performed complex jobs (such as computer programmers, quality control experts and engineers) and were exposed to high ambient noise levels had a threefold increase in systolic blood pressure and a twofold increase in diastolic blood pressure compared with those performing simple jobs (such as machine operators and assembly line workers).

Previous studies have shown that job complexity is associated with greater job challenge and stimulation and it is expected to positively affect employees' psychological well-being and motivation. However, this study is important, say the authors, as it shows for the first time that the above holds only for those with favorable environmental conditions, such as low ambient noise levels.

On the other hand, those who perform complex jobs under highly intrusive background noise may require additional attention and concentration, causing stress. These workers become dissatisfied with their job and are at increased risk for cardiovascular disease, according to the study.

The study also found that workers in simple jobs may benefit from exposure to moderate noise levels. Compared to other workers in simple jobs exposed to low ambient noise, those exposed to moderate noise levels showed much lower blood pressure change over time and considerable less reduction in job satisfaction. "Exposure to moderate noise levels may be arousing and offset the understimulation associated with the boredom and monotony likely to be experienced in simple jobs," said the authors.
First Article: "Correlates of Work Injury Frequency and Duration Among Firefighters," Hui Liao, Richard D. Arvey, and Richard J. Butler, University of Minnesota and Steven M. Nutting, City of Minneapolis, Minnesota; Journal of Occupational Health Psychology, Vol. 6, No. 3.

Full text of the article is available from the APA Public Affairs Office or at

Lead author Hui Liao can be reached at 612-626-2063 or by e-mail at

Second Article: "The Interactive Effect of Chronic Exposure to Noise and Job Complexity on Changes in Blood Pressure and Job Satisfaction: A Longitudinal Study of Industrial Employees," Samuel Melamed, National Institute of Occupational and Environmental Health, Yitzhak Fried, Wayne State University, and Paul Froom, National Institute of Occupational and Environmental Health; Journal of Occupational Health Psychology, Vol. 6, No. 3.

Full text of the article is available from the APA Public Affairs Office or at

Lead author Samuel Melamed, Ph.D., can be reached at (011) 972-9-7707230 or by e-mail at

The American Psychological Association (APA), in Washington, DC, is the largest scientific and professional organization representing psychology in the United States and is the world's largest association of psychologists. APA's membership includes more than 155,000 researchers, educators, clinicians, consultants and students. Through its 53 divisions of psychology and affiliations with 60 state, territorial and Canadian provincial associations, APA works to advance psychology as a science, as a profession and as a means of promoting human welfare.

American Psychological Association

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