Heat stress due to ambient outdoor temperatures is a workplace hazard that has not been well studied or characterized. The incidence of occupational heat-related illness is unknown. Heat-related morbidity and mortality have been well-studied at the population level, however it cannot be determined if these findings extend systematically to workers exposed to high heat conditions. Remarkably, there is no U.S. federal standard to protect workers from the peril of elevated environmental temperatures and few states have protective regulations. This dissertation research will add to the limited knowledge base of occupational heat-related illnesses, by characterizing worker fatalities due to environmental heat stress. Three independent, but related, research strategies were designed, executed, and completed to evaluate the current research, as well as knowledge gaps, and to thoroughly describe these fatalities based on available information. This work was initiated with a thorough literature review to summarize research findings that characterize U.S. occupational heat-related morbidity and mortality and identify gaps in the existing research literature. This review of science, health, and medical databases found that few studies examine ambient heat stress or characterize the incidence of occupational heat-related illnesses and outcomes. Significantly more research examining the heterogeneity of worker and environmental risk factors to heat exposure is needed to identify unsafe working conditions and implement practical, evidence-based heat-stress policies and interventions. The subsequent study describes the epidemiological characteristics of heat-related deaths among workers in the U.S. from 2000 to 2010. Fatality data were obtained at the Bureau of Labor Statistics from the confidential on-site Census of Fatal Occupational Injuries database. Fatality rates and risk ratios with 95% confidence intervals were calculated by year, sex, age group, ethnicity, race, state, and industry. Between 2000 and 2010, 359 occupational heat-related deaths were identified in the U.S., for a yearly average fatality rate of 0.22 per 1 million workers. Highest rates were found among Hispanics, men, the agriculture and construction industries, the states of Mississippi and Arkansas, and very small establishments. This study provides the first comprehensive national profile of heat-related deaths in the U.S. workplace. Prevention efforts should be directed at small businesses, states, industries and individuals who may be at increased risk of heat stress. Lastly, to further characterize these fatalities, research was performed to: 1) determine the ranges of heat index and temperature at which workers fatally succumb to environmental heat; 2) identify risk factors that may influence heat-related deaths; and 3) translate these findings to policy recommendations. The Census of Fatal Occupational Injuries and the National Climate Data Center were used to identify worker heat-related deaths in the U.S., 2000- 2010, and to assign a maximum daily temperature and heat index to each case. Demographic, meteorological, and geographical variables were analyzed to evaluate any differences in fatal heat exposure. The National Weather Service temperature alert tools, the Excessive Heat Event warning and the heat index category chart, were utilized to assess community threshold suitability for workers subjected to exertional heat stress. Of the 327 cases that qualified for the analysis, there were no differences found in mean temperatures and heat indexes between the sexes, races, age groups, ethnic groups, and industries. Southern workers died at significantly higher temperatures than workers in the North. This study supports the use of heat index and temperature as a guide when evaluating environmental conditions for workers. Population-level heat index threshold alerts are unsuitable for preventing exertional heat stress and new warning systems should be developed. Since heat-related health hazards at work can be anticipated before they manifest, preventive measures can be implemented before illness occurs. With no federal regulatory standards to protect workers from environmental heat exposure, and with climate change as a driver for adaptation and prevention of heat disorders, it is increasing sensible and imperative for the Occupational Safety and Health Administration to take action. National leadership is needed to promulgate regulations, develop new heat alert tools using the heat index as a metric, and promote state-specific occupational heat stress prevention policies.
Health Sciences ; Occupational Health And Safety|Climate Change|Environmental Health
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