Working on a warmer planet: The impact of heat stress on labour productivity and decent work


This report, by the Work Income and Equity Unit of the International Labour Organization’s Research Department, was published on July 1, 2019. It was prepared as a follow up to ILO’s Guidelines for a just transition towards environmentally sustainable economies and societies for all, which invite governments to assess increased or new occupational safety and health risks resulting from climate change.

‘Heat stress’ is defined as “… heat received in excess of that which the body can tolerate without suffering physiological impairment.” A body’s internal mechanisms cannot maintain body temperature at a level required for normal functioning above a certain level of heat stress, the report notes. This results in increased discomfort, limitations in physical functions and capabilities, and injuries and heat-related illnesses. Climate change and the rise in global temperatures is likely to make heat stress more common. The report states that this will reduce workers’ productivity, family income and ‘economic output’.

The nine-part report covers the impact of heat stress on ‘decent work’ (chapter 1); a global overview of heat stress (chapter 2); heat levels and labour market trends in Africa (chapter 3), North and South America (chapter 4), Arab States (chapter 5), Asia and the Pacific (chapter 6), Europe and Central Asia (chapter 7); adapting to hazards related to heat through international labour standards (chapter 8); and mitigation efforts to reduce hazards related to heat (chapter 9).


  1. The report states that a worker’s natural defence mechanism against heat stress is to slow down work, take more breaks and limit the number of working hours. Temperatures above 24 to 26°C are associated with reduced labour productivity; at 33 to 34°C, a worker operating at ‘moderate work intensity’ loses 50 per cent of their work capacity.

  2. Heat stress affects workers in all sectors, especially occupations which involve more physical effort or take place outdoors. Such jobs are typically found in agriculture, ‘natural resource management’, construction, refuse collection, emergency repair work, transport, tourism and sports. Industrial work in indoor settings can also be at risk if temperatures inside factories and workshops are not adequately regulated.

  3. Agricultural and construction workers are expected to be the worst affected by heat stress among these occupations. The report states that the agricultural sector accounted for 83 per cent of the ‘global working hours’ lost due to heat stress in 1995. The sector is projected to account for 60 per cent of the loss in global working hours in 2030. And a large number of workers will be displaced as temperature rises render agricultural areas unproductive.

  4. Countries most affected by heat stress also have higher rates of poverty, informal employment and subsistence agriculture. The report notes that 4 of the 20 sub-regions it studied are expected to suffer a loss of 3 per cent or more in ‘total working hours’ in the year 2030: South Asia, West Africa, South-East Asia and Central Africa.

  5. Globally, about 1.4 per cent of total working hours were lost due to heat stress in 1995, representing nearly 35 million full-time jobs worldwide. It is projected that 2.2 per cent of total working hours – representing about 80 million full-time jobs worldwide – will be lost as a result of temperature rises caused by climate change in 2030.

  6. Countries such as Bangladesh, Cambodia, India, Pakistan, Thailand and Vietnam are most vulnerable to ‘productivity losses’ due to their high shares of employment in the agricultural or construction sectors, and because they are located within the tropical and subtropical latitudes.

  7. Due to the impact of heat stress on labour productivity, the report states, Cambodia, India, Pakistan and Thailand are projected to see a 5 per cent reduction in their gross domestic product in 2030.

  8. The brickmaking industry in India employs millions of people including young children, the report notes, who work under harsh conditions and receive low wages. They face severe risks due to high temperatures and ‘radiant heat levels’ when the bricks are fired, and they also carry heavy physical loads. The report cites a 2014 study – Effects of occupational heat exposure on female brick workers in West Bengal, India by Moumita Sett and Subhashis Sahu (researchers at the University of Kalyani, West Bengal), which found that an increase in temperature of 1°C causes a loss in productivity of about 2 per cent. The majority of the workers surveyed in this study were aware of their heat stress symptoms, but lacked the resources to tackle them.

  9. The report suggests the ‘transformation’ of rural economies to avoid the impact of heat stress, such that fewer agricultural workers are exposed to high temperatures and less physical effort has to be expended in such conditions. Occupational safety and health, and the development of sustainable or ‘green’ businesses should be promoted, and governments must regulate the maximum temperatures that workers may be exposed to.

    Focus and Factoids by Shrushti Bhosale.


International Labour Organization


International Labour Organization, Geneva 


01 Jul, 2019