Estimating population heat exposure and impacts on working people in conjunction with climate change


Increased environmental heat levels as a result of climate change present a major challenge to the health, wellbeing and sustainability of human communities in already hot parts of this planet. This challenge has many facets from direct clinical health effects of daily heat exposure to indirect effects related to poor air quality, poor access to safe drinking water, poor access to nutritious and safe food and inadequate protection from disease vectors and environmental toxic chemicals. The increasing environmental heat is a threat to environmental sustainability. In addition, social conditions can be undermined by the negative effects of increased heat on daily work and life activities and on local cultural practices. The methodology we describe can be used to produce quantitative estimates of the impacts of climate change on work activities in countries and local communities. We show in maps the increasing heat exposures in the shade expressed as the occupational heat stress index Wet Bulb Globe Temperature. Some tropical and sub-tropical areas already experience serious heat stress, and the continuing heating will substantially reduce work capacity and labour productivity in widening parts of the world. Southern parts of Europe and the USA will also be affected. Even the lowest target for climate change (average global temperature change = 1.5 °C at representative concentration pathway (RCP2.6) will increase the loss of daylight work hour output due to heat in many tropical areas from less than 2% now up to more than 6% at the end of the century. A global temperature change of 2.7 °C (at RCP6.0) will double this annual heat impact on work in such areas. Calculations of this type of heat impact at country level show that in the USA, the loss of work capacity in moderate level work in the shade will increase from 0.17% now to more than 1.3% at the end of the century based on the 2.7 °C temperature change. The impact is naturally mainly occurring in the southern hotter areas. In China, the heat impact will increase from 0.3 to 2%, and in India, from 2 to 8%. Especially affected countries, such as Cambodia, may have losses going beyond 10%, while countries with most of the population at high cooler altitude, such as Ethiopia, may experience much lower losses.

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  1. ACGIH (2011) TLVs for chemical substances and physical agents & biological exposure indicators. Cincinnati, American Conference of Government Industrial Hygienists

    Google Scholar 

  2. Bernard TE, Pourmoghani M (1999) Prediction of workplace wet bulb global temperature. Appl Occup Environ Hyg 14:126–134

    CAS  Article  Google Scholar 

  3. Bilbao J, de Miguel AH, Kambezidis HD (2002) Air temperature model evaluation in the north Mediterranean belt area. J Appl Meteorol 41:872–884

    Article  Google Scholar 

  4. Blazejczyk K, Epstein Y, Jendritzky G, Steiger H, Tinz B (2012) Comparison of UTCI to selected thermal indices. Int J Biometeorol 56:515–535

    Article  Google Scholar 

  5. Bouchama A, Knochel JP (2002) Medical progress—heat stroke. N Engl J Med 346:1978–1988

    CAS  Article  Google Scholar 

  6. Collins M, Knutti R, Arblaster J, Dufresne J-L, Fichefet T, Friedlingstein P, Gao X, Gutowski WJ, Johns T, Krinner G, Shongwe M, Tebaldi C, Weaver AJ, Wehner M (2013) Long-term climate change: projections, commitments and irreversibility. In: Stocker TF, Qin D, Plattner G-K, Tignor M, Allen SK, Boschung J, Nauels A, Xia Y, Bex V, Midgley PM (eds) Climate change 2013: the physical science basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge s

    Google Scholar 

  7. DARA (2012) Climate vulnerability monitor 2012. Fundacion DARA Internacional, Madrid

    Google Scholar 

  8. Fiala D, Havenith G, Broede P, Kampmann B, Jendritzky G (2012) UTCI-Fiala multi-node model of human heat transfer and temperature regulation. Int J Biometeorol 56:429–441

    Article  Google Scholar 

  9. Hales S, Kovats S, Lloyd S, Campbell-Lendrum D (2014) Quantitative risk assessment of the effects of climate change on selected causes of death. World Health Organization, Geneva

  10. Harris I, Jones PD, Osborn TJ, Lister DH (2014) Updated high-resolution grids of monthly climatic observations—the CRU TS3.10 dataset. Int J Climatol 34:623–642

    Article  Google Scholar 

  11. Havenith G, Fiala D (2016) Thermal indices and thermo-physiological modelling for heat stress. Compr Physiol 6:255–302

    Google Scholar 

  12. Hempel S, Frieler K, Warsawski L, Schewe J, Piontek F (2013) A trend-preserving bias correction—the ISI-MIP approach. Earth Syst Dynam 4:219–236

    Article  Google Scholar 

  13. Hyatt O, Lemke B, Kjellstrom T (2010). Regional maps of occupational heat exposure: past, present and potential future. Glob Health Action. 3: on website. Doi: 10.3402/gha.v3i0.5715)

  14. ISO (1989) Hot environments—estimation of the heat stress on working man, based on the WBGT-index (wet bulb globe temperature). ISO Standard 7243. International Standards Organization, Geneva

    Google Scholar 

  15. Jensen ME, Burman RD, Allen RG (1990) Evapotranspiration and irrigation water requirements. ASCE manual and report on engineering practices no. 70. NY: American Society of Civil Engineers; 1990, p. 332

  16. Kjellstrom T, Holmer I, Lemke B (2009a) Workplace heat stress, health and productivity—an increasing challenge for low and middle income countries during climate change. Glob Health Action (on website: doi:10.3402/gha.v2i0.2047

  17. Kjellstrom T, Kovats S, Lloyd SJ, Holt T, Tol RSJ (2009b) The direct impact of climate change on regional labour productivity. Int Arch Environ Occup Health 64:217–227

    Article  Google Scholar 

  18. Kjellstrom T, Lemke B, Otto M (2013) Mapping occupational heat exposure and effects in South-East Asia: ongoing time trends 1980-2009 and future estimates to 2050. Ind Health 51:56–67

    Article  Google Scholar 

  19. Kjellstrom T, Lemke B, Otto M, Hyatt O, Dear K. (2014) Occupational heat stress. Contribution to WHO project on “Global assessment of the health impacts of climate change”, which started in 2009. ClimateCHIP Tech Rept 2014:4 (on website:

  20. Lemke B, Kjellstrom T (2012) Calculating workplace WBGT from meteorological data. Ind Health 50:267–278

    Article  Google Scholar 

  21. MMWR (2008) Heat-related deaths among crop workers—United States, 1992-2006. JAMA 300:1017–1018 (also MMWR, 2008, 57: 649-653)

    Article  Google Scholar 

  22. Niemelä R, Hannula M, Rautio S, Reijula K, Railio J (2002) The effect of air temperature on labour productivity in call centres—a case study. Energy Build 34:759–764

    Article  Google Scholar 

  23. NIOSH (2016) NIOSH criteria for a recommended standard: occupational exposure to heat and hot environments. By Jacklitsch B, Williams WJ, Musolin K, Coca A, Kim J-H, Turner N. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication 2016-106

  24. NOAA (2016) Vapor pressure NOAA report: accessed Nov 2016

  25. Parsons K (2014) Human thermal environment. The effects of hot, moderate and cold temperatures on human health, 3rd edn. CRC Press, New York

    Google Scholar 

  26. PIK (2016) Potsdam Institute for climate impact research., Potsdam

  27. Sahu S, Sett M, Kjellstrom T (2013) Heat exposure, cardiovascular stress and work productivity in rice harvesters in India: implications for a climate change future. Ind Health 51:424–431

  28. Samir KC, Lutz W (2014) The human core of the shared socioeconomic pathways: population scenarios by age, sex and level of education for all countries to 2100. Global Environ Change (web:

  29. Schulte PA, Chun HK (2009) Climate change and occupational safety and health: establishing a preliminary framework. J Occup Environ Hyg 6:542–554

    CAS  Article  Google Scholar 

  30. Smith KR, Woodward A, Campbell-Lendrum D, Chadee DD, Honda Y, Liu Q, Olwoch JM, Revich B, Sauerborn R (2014) Human health: impacts, adaptation, and co-benefits. In: Field CB, Barros VR, Dokken DJ, Mach KJ, Mastrandrea MD, Bilir TE, Chatterjee M, Ebi KL, Estrada YO, Genova RC, Girma B, Kissel ES, Levy AN, MacCracken S, Mastrandrea PR, White LL (eds) Climate change 2014: impacts, adaptation, and vulnerability. Part A: global and sectoral aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, pp 709–754 (IPCC AR5 WG2 Ch 11)

    Google Scholar 

  31. UNDP (2016) Climate change and labour: impacts of heat in the workplace. Issue paper. Geneva, CVF Secretariat, United Nations Development Program.

  32. USDAAF (2003) Heat stress control and heat casualty management. Technical Bulletin TB MED 507/AFPAM 48-152 (I). US Department Army and Air Force, Washington DC

    Google Scholar 

  33. Warsawski L, Frieler K, Huber V, Piontek F, Serdeczny O, Scewe J (2014) The Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP): project framework. PNAS 111:3228–3232

    Article  Google Scholar 

  34. WMO (2016) Climate. Geneva, World Meteorological Organization (web:

  35. Wyndham CH (1969) Adaptation to heat and cold. Environ Res 2:442–469

    CAS  Article  Google Scholar 

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This research was supported by funds from the Pufendorf Institute at Lund University, Sweden, and the European Union’s Horizon 2020 research and innovation programme under grant agreement No 668786 (HEAT-SHIELD project).

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Correspondence to Tord Kjellstrom.

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Kjellstrom, T., Freyberg, C., Lemke, B. et al. Estimating population heat exposure and impacts on working people in conjunction with climate change. Int J Biometeorol 62, 291–306 (2018).

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  • Climate change
  • Heat
  • Work
  • Health impacts
  • Social/economic impacts