This project will study the complex threat heat exposures pose to human health, wellbeing and productivity in working populations in Singapore and other tropical countries, and to identify sustainable preventive policies and actions that can reduce these impacts. Working people are particularly vulnerable to environmental heat because of their added internal heat production from muscle work. Singapore’s equatorial location means working populations are already chronically exposed to hot conditions (WBGT > 25°C) which are considered detrimental to health and wellbeing. These conditions require people working or engaged in exercise outdoors to take frequent rest and cooling breaks to protect health, If workers cannot or do not take rest in relation to heat stress, serious health effects can occur, including heat stroke death. Such conditions also affect productivity, which is reduced by 15% of potential annual work hours in the sun and by 4% if working in the shade.

Singapore has begun to tackle these issues by supporting mitigation and adaptation to extreme heat associated with climate change and with the urban heat island effect through research focused on public health and urban design. However, heat-health is a complex socioenvironmental problem that transgresses institutional, sectoral and disciplinary boundaries of public and occupational health and the domains of workplace, public space and the home. As such, there is a need to complement these efforts through the provision of a programme focussed on occupational exposures and their knock-on effects to support the overall effectiveness of Singaporean investments in heat-health risk management. Exposed work occurs in outdoor settings, but semi-enclosed workspaces, such as sheds or roofed workshops, can also present very hot thermal environments where cooling systems are inefficient, air conditioning cannot be used for financial or other reasons, and/or additional heat sources are present. These conditions are typical of many industries, including construction, shipping and utilities, including oil and gas transport and storage.

There is also limited evidence available concerning occupational heat exposures, and the impact of age, body mass index, physical fitness, and sex (e.g. pregnancy) on these effects, or their broader effects, such as prolonged discomfort, and mental stress, familial relationships and special health concerns, such as fertility. Improved knowledge is essential for the development of effective prevention programs. The researchers will pursue a multi-disciplinary approach uniquely positioned to address direct occupational heat exposures and impacts on health and productivity, but also the broader health and wellbeing implications that have yet to be comprehensively addressed in chronically heat-exposed countries such as Singapore. For example, physical fitness is one of the best ways of increasing heat tolerance as well as overall health. Ironically, the high heat levels in Singapore do not only discourage engagement in physical exercise, but can also be a direct health threat for people involved in sports and exercise. We will also review and test methods for analysing the most extreme effects of heat, including heat related mortality.

By following impacts on workers as well as workplaces, the study will trace how heat-health impacts emerge through exposure and exertion as a result of behaviours shaped by the climatic, urban, occupational and social environments they traverse every day. Such integrated analysis is required in order to develop policy responses that take into account the spatial and social situation of why heat-health impacts occur and how they can be managed as part of the everyday lives of chronically exposed populations. This also allows for the identification, analysis and management of ‘knock-on’ effects of occupational heat exposures on recreational and domestic life (and vice versa), including psychosocial and physiological impacts on exercise behaviours and fitness, family relationships, mental health and wellbeing and fertility rates. As our focus is on heat effects on working people, one secondary outcome of excessive heat exposure will be economic losses at individual, enterprise, community and national level due to a reduction of labour productivity due to heat. Our analysis will compare such economic impacts of heat to the costs of potential methods for climate change mitigation in selected countries. This will provide new estimates of the value of different alternatives in future climate change policy development.