Heat stress is a recognized hazard for construction workers. To ensure safety and health of the workers, it is important to study the heat stress and thermal environment in construction sites, and develop practical solutions to avoid adverse health effects and accidents. In typical construction sites, the employees have to work long hours in thermally stressful environments, and with heavy physical workload, especially during summer time. As a result, they are at high risk and this may pose special hazards of heat stress. This research examines different kinds of heat stress indices and standards in the world. The result indicates that wet bulb globe temperature (WBGT) is a major factor affecting the level of heat stress because the rate of evaporation from human body is limited when WBGT increases. It is also found that some indexes provide little common agreement for the exposure limit and time; some can only be used for preliminary heat stress evaluation. In general, metabolic rate is the most difficult part to estimate in the heat stress equation for construction workers. It is concluded that engineering and administration method is the most effective way to control heat stress. Moreover, training and education for the employees are critical preventing accidents in construction sites.postprintThe Hunan-Hong Kong Joint Symposium 2011, Changsha, Hunan, China, 1-2 July 2011. In Proceedings of the Hunan-Hong Kong Joint Symposium, 2011, p. 52-612011湘港建築設備工程技術交流會, 中國, 湖南, 長沙, 2011年7月1日至2日. 會議記錄, 2011, p. 52-6
