The heat is on : Evaluation of workplace heat stress under a changing climate

Abstract: Background: There are several scientific indications that increasing heat due to climate change is going to become the next big societal and scientific challenge. Climate change is recognized as a significant public health threat. However, there is a lack of research on its impacts on occupational safety and health. Aims and Objectives: The general aim of the research presented in this thesis was to identify impacts, evaluate assessment tools and explore solutions to the effects of increasing heat at different workplaces. The research had four specific objectives: 1) To identify gaps in the existing knowledge of occupational heat stress and its links with a changing climate (Papers I, II, V). 2) To carry out a field study in workplaces situated in already hot areas of the world, namely in Chennai, India, in order to assess the current and future impacts of increasing local heat due to climate change (Papers II, V). 3) To evaluate the current standard assessment tools for hot environments (Papers II, III). 4) To investigate site-specific sustainable solutions to increasing heat, including technical, managerial and socio-cultural solutions (Papers II, IV, V). Methods: To address the specific objectives, a wide array of research techniques and qualitative and quantitative methods were used. The methods included literature reviews, case studies, heat stress assessment techniques, questionnaire surveys, thermal manikin measurements, application of thermophysiological models and an experimental study conducted in a climatic chamber.Results: This research showed that occupational heat exposure is already a problem in Chennai, India, affecting workers’ health and productivity. The problems are set to worsen due to climate change. Female workers are more prone to heat stress due to the use of clothing that inhibit heat dissipation. Physiological models are also less accurate in predicting heat strain for females. The Predicted Heat Strain (PHS) model (ISO 7933:2004a) can be applied to estimate thermal physiological responses and indirectly to estimate labour productivity loss due to heat exposure. However, caution has to be taken when analysing intermittent work as the PHS over-predicts body cooling at low activity. Traditional methods of coping with heat stress were analysed and the traditional Indian fermented dairy drink, ‘buttermilk’, proved to be as effective as water in reducing thermal strain. Buttermilk also had a protective effect on renal function. The analysis and evaluation of solutions require transdisciplinary and holistic approaches, including not only technical solutions but also a mix of locally appropriate technologies integrated with a human rights and environmental justice frame.Conclusion: Occupational heat stress is already a problem, affecting workers’ health and productivity. The situation is bound to worsen due to climate change. Because of this, it is important to assess and validate current assessment tools and develop sustainable solutions.