Climate change, heat exposure and labour productivity.

“Too hot” working environments are not just a question of “comfort”, but a real concern for health protection and ability to perform work tasks. For un-acclimatized persons, already at temperatures above 22.5 degrees C the ability to perform at full capacity is reduced, and for acclimatized persons this reduction starts at 26 degrees C (WBGT). The reduction in work ability can be considered a form of “disability” that should be taken into account when assessing the “burden of disease or ill health” caused by global warming. People in tropical developing countries are to some extent acclimatized to the climate in their area of residence, but high temperatures still affect their ability to work. The international standard for work in hot environments (ISO, report 7243, 1989) provides a framework for analyzing the reduction of physical work ability as temperature increases, and it takes acclimatization into account. The standard identifies maximum WBGT temperatures for continuous work (8 hours per day), 75% reduction of work hours, 50% reduction, etc. If work continues beyond these limits the worker is at high risk of diminished work ability, diminished mental task ability, increased accident risk and heat stroke. Converting these relationships for different work intensity into functions showing the reduction of work ability as temperature increases indicates that, even with only one degree increase in temperature (from an already hot temperature) the reductions of work ability can be quite dramatic: up to 30% or more. The consequences of a temperature shift for the work ability of populations in selected developing and developed countries are analyzed and calculated in the form of “burden of ill health”.