24-hour work shifts, sedentary work, and obesity in male firefighters.

Background: Little is known about the occupational risk factors for obesity in US firefighters.

Methods: 308 male California firefighters, who participated in a work and obesity project, were chosen. Working conditions were measured with a firefighter-specific occupational health questionnaire. Adiposity was clinically assessed using body mass index (BMI), waist circumference (WC), and body fat percent.

Results: In a multivariate analysis, the prevalence of obesity by all measures was significantly higher (PRs = 3.69-6.03, P < 0.05) in the firefighters who reported seventeen to twenty-one shifts than those who reported eight to eleven shifts in the past month. Prolonged sedentary work was also a risk factor for obesity by BMI (PR = 4.18, P < 0.05). Furthermore, there was a linear dose-response relationship of obesity by BMI and WC with the number of 24-hr shifts and sedentary work.

Conclusions: Many additional 24-hr shifts and prolonged sedentary work substantially increased the risk for obesity in male firefighters. Am. J. Ind. Med. 59:486-500, 2016. © 2016 Wiley Periodicals, Inc.