Heat Stress: The Impact of Ambient Temperature on Occupational Injuries in the US

Work-related injuries in the US generate annual costs exceeding 250 billion, with approximately one third of these costs coming from the direct health care expenses of dealing with the injuries and the remainder coming from the impacts on economic productivity associated with accidental injury. Beyond these costs, considerable expenses and efforts are devoted to avoiding injuries, and monitoring workplaces for compliance with safety rules. There are many factors that can increase the probability of workplace accidents, as well as a variety of regulations and regulatory agencies designed to reduce or limit these factors and to monitor compliance with regulations by employers. Of course there are some factors that even the most well-intentioned employers can not control, or that may not be easy to regulate at the local or even the national level. In this paper we investigate one of these factors: the ambient temperature within which work takes place. Clinical and empirical evidence such as that presented in Colquhoun (1969), Chiles (1958) or Azer, McNall and Leung (1972) indicates that high temperatures and heat stress diminish mental alertness, vigilance and ability to perform complex tasks. In a recent paper, Deschenes and Greenstone (2011) documented the potential impact of climate change on mortality in the US. Their research indicates that between 2010 and 2099, increased temperature could be expected to increase annual mortality rates in the US by about 3%, with about half of the heat-related deaths occurring in the South Atlantic and West South Central regions of the US. We investigate the impact of increased temperature on occupational injuries in heat-sensitive industries in the US, providing what appear to be the first available estimates of the impact of increased ambient temperatures on workplace injuries. Using some approximations from climate models we provide estimates of the potential economic cost of climate change caused by this previously undiscussed mechanism.