Case Report

Productivity Loss from Occupational Exposure to Heat Stress: A Case Study in Brick Workshops/Qom-Iran


Heat stress particularly  at  outdoor  workplaces in hot-dry    climates can  disrupt    the physical or mental functions and effect negatively on human performance. We aimed to study the effect of heat stress on productivity loss among workers of brick workshops in Qom Province – central Iran. This cross-sectional descriptive and analytic study was performed on 184 workers in 40 brick workshops. Environmental parameters including dry temperature, natural wet-bulb temperature, globe temperature, relative humidity and air velocity were measured at three times during work shift. WBGT (Wet Bulb Globe Temperature) heat stress index was calculated based on equation provided by Australian Bureau of Meteorology. Potential  labor productivity losses due  to  heat  stress  were  determined using  a  graph presented already. The total average of WBGT was 31.84±3.46°C. WBGT index according to different jobs  was  39.48±8.2°C, 29.86±2.79°C, 29.31±0.97°C and  28.69±1.89°C for working in  kiln,  material handling,  working  on  conveyor and  making  adobe,  respectively.  The  average  loss  productivity  in mentioned tasks was 93.57±16.54, 66.58±20.58, 65.53±15.26 and 48.27±13.04 respectively, with total average of productivity loss 68.48±16.35%. The statistically significant relationships were found between WBGT values and percentage of loss productivity in total and for all understudy jobs (p<0.001). Heat stress can lead to decrease in labor productivity at outdoor workplaces like brick industries. According to climate change in the future and gradual global warming, paying more attention to the occupational health issues in outdoor workplaces at dry and warm environment seems to be more important than before.

Monazzam MR, Golbabaei F, Hematjo R, Hosseini M, Nassiri P, Dehghan SF. Evaluation of DI, WBGT and Swreq/PHS Heat Stress Indices for Estimating the Heat Load on the Employees of a Petrochemical Industry. IJOH 2014; 6 (1): 6-10.

Parvari RA, Aghaei HA, Dehghan H, Habibi E, Maracy MR, Dehghan SF. The effect of fabric type of common Iranian working cloth on the induced cardiac and physiological strain under heat stress. Arch Environ Occup Health 2014;. doi: 10.1080/19338244.2014.891965.

Golbabaei F, Monazzam MR, Hematjo R, Hosseini M, Dehghan SF. The assessment of heat stress and heat strain in Table 2. Calculation results of loss of productivity and relationship between loss productivity and WBGT Type of Work parameters Material handling Kiln Working on conveyor Making adobe Total Productivity loss )%( Mean 66.58 93.57 65.53 48.27 68.48 SD 20.58 16.54 15.26 13.04 16.35 Range 84 54 38 67 60.75 Productivity loss )%) vs. WBGT (oC) Correlation coefficient 0.67 0.67 0.913 0.985 0.81 p-value <0.001 <0.001 <0.001 <0.001 <0.001 pardis petrochemical complex, Tehran, Iran. IJOH 2013;5(1):6-11.

Lin R-T, Chan C-C. Effects of heat on workers' health and productivity in Taiwan. Glob Health Action 2009. 2: 10.3402/gha.v2i0.2024.

The Office of Radiation, Chemical and Biological Safety, Michigan State University .MSU Employee Guidelines for Working in hot Environments. 1999[cited 2014 10, 1]; Available from: eat_stress/heatstressmanual.pdf.

Langkulsen U, Vichit-Vadakan N, Taptagaporn S. Health impact of climate change on occupational health and productivity in Thailand. Glob Health Action 2010; 3: 10.3402/gha.v3i0.5607.

Enander AE. Effects of thermal stress on human performance. Scand J Work Environ Health 1989; 15(1) 27-33.

Hancock P, Vasmatzidis I. Effects of heat stress on cognitive performance: the current state of knowledge. Int J Hyperthermia 2003; 19(3):355-72.

Jay O, Kenny GP. Heat exposure in the Canadian workplace. Am J Ind Med 2010; 53(8):842-53.

Miller V, Bates G. Hydration of outdoor workers in northwest Australia. J Occup Health Saf Aust NZ 2007; 23(1):79- 87.

Kjellstrom T, Holmer I, Lemke B. Workplace heat stress, health and productivity–an increasing challenge for low and middle-income countries during climate change. Glob Health Action 2009; 2: 10.3402/gha.v2i0.2047.

Climatevo. Qom weather, Iran, Islamic Republic of - climate information 2014 [cited 2014 10, 1]. Available from:,ir.

ACGIH. TLVs and BEIs. Thermal Stress: American Conference of Industrial Hygienists; 2014.

ISO. ISO 9920, Ergonomics of the thermal environment -- Estimation of thermal insulation and water vapour resistance of a clothing ensemble. International Organization for Standardization; 2007.

Kjellstrom T, Lemke B, Holmér I. Climate change and occupational heat stress. Proceedings of the International Congress on Biometeorology, 22-26 September 2008; Tokyo, Japan.

Lemke B, Kjellstrom T. Calculating workplace WBGT from meteorological data: a tool for climate change assessment. Ind Health 2012; 50(4):267-78.

Haji Azimi E, Khavanin A, Aghajani M, Soleymanian A. Thermal stress measurement according to WBGT index in smelting industry. IJMS 2011; 13(2):59-64.

Gomes J, Lloyd O, Norman N. The health of the workers in a rapidly developing country: effects of occupational exposure to noise and heat.Occup Med 2002; 52(3):121-8.

Tatterson AJ, Hahn AG, Martini DT, Febbraio MA. Effects of heat stress on physiological responses and exercise performance in elite cyclists. J Sci Med Sport 2000; 3(2):186- 93.

Wyon DP, Andersen I, Lundqvist GR. The effects of moderate heat stress on mental performance. Scand J Work Environ Health 1979; 5:352-361.

Mathee A, Oba J, Rose A. Climate change impacts on working people (the HOTHAPS initiative): findings of the South African pilot study. Glob Health Action. 2010; 3: 10.3402/gha.v3i0.5612.

IssueVol 6 No 3 (2014) QRcode
SectionCase Report(s)
Loss of Productivity Heat Stress WBGT Brick Workshops

Rights and permissions
Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
How to Cite
Hajizadeh R, Golbabaei F, Monazzam MR, Farhang-Dehghan S, Ezadi-Navan E. Productivity Loss from Occupational Exposure to Heat Stress: A Case Study in Brick Workshops/Qom-Iran. Int J Occup Hyg. 2015;6(3):143-148.