Climate change leads to increasing temperatures, shifting rainfall patterns and more extreme weather events, which affect occupational health in many ways. Heat stress at work poses health risks and reduced work capacity, presenting a new and widespread occupational health challenge due to climate change.
Human physiology limits to coping with heat stress are well known, but the links to climate change need further analysis. Occupational health effects include heat exhaustion (reducing work capacity), serious heat stroke (including deaths), dehydration effects on the kidneys, and exacerbation of chronic diseases. Cognitive performance is also affected by heat stress. Physical work significantly adds to heat stress because of internal heat production from muscles. Working people slow down or take frequent breaks (self-pacing) to compensate. As a result, reduced productivity creates economic losses.
We compared population based estimates of health impacts of heat stress for selected climate models applied to the four different “Representative Concentration Pathways” of greenhouse gases established by the UN Intergovernmental Panel on Climate Change (IPCC).
Serious ambient heat stress conditions currently occur 1–2% of annual daylight hours in hot tropical low altitude countries (e.g. Nicaragua or Bangladesh), while higher altitude countries (e.g. Ethiopia) or less hot sub-tropical countries (e.g. Greece) have less than 0.2% hours affected. The “business as usual” pathway creates heat stress risks for 10–20% of annual daylight hours in 2085 in the tropics. The climate change mitigation programs offered at the recent UN Framework Convention on Climate Change (UNFCCC) Paris summit may only halve these risks. In many low income countries the loss of work hours will create substantial reductions of annual GDP. Stricter global climate policies are needed, and occupational epidemiology research is essential to develop health impact assessments essential for decision-making to protect millions of working people in vulnerable countries.