MMWR Morb Mortal Wkly Rep. 2018 Jul 6;67(26):733-737. doi: 10.15585/mmwr.mm6726a1.
Heat stress, an environmental and occupational hazard, is associated with a spectrum of heat-related illnesses, including heat stroke, which can lead to death. CDC's National Institute for Occupational Safety and Health (NIOSH) publishes recommended occupational exposure limits for heat stress (1). These limits, which are consistent with those of the American Conference of Governmental Industrial Hygienists (ACGIH) (2), specify the maximum combination of environmental heat (measured as wet bulb globe temperature [WBGT]) and metabolic heat (i.e., workload) to which workers should be exposed. Exposure limits are lower for workers who are unacclimatized to heat, who wear work clothing that inhibits heat dissipation, and who have predisposing personal risk factors (1,2). These limits have been validated in experimental settings but not at outdoor worksites. To determine whether the NIOSH and ACGIH exposure limits are protective of workers, CDC retrospectively reviewed 25 outdoor occupational heat-related illnesses (14 fatal and 11 nonfatal) investigated by the Occupational Safety and Health Administration (OSHA) from 2011 to 2016. For each incident, OSHA assessed personal risk factors and estimated WBGT, workload, and acclimatization status. Heat stress exceeded exposure limits in all 14 fatalities and in eight of 11 nonfatal illnesses. An analysis of Heat Index data for the same 25 cases suggests that when WBGT is unavailable, a Heat Index screening threshold of 85°F (29.4°C) could identify potentially hazardous levels of workplace environmental heat. Protective measures should be implemented whenever the exposure limits are exceeded. The comprehensive heat-related illness prevention program should include an acclimatization schedule for newly hired workers and unacclimatized long-term workers (e.g., during early-season heat waves), training for workers and supervisors about symptom recognition and first aid (e.g., aggressive cooling of presumed heat stroke victims before medical professionals arrive), engineering and administrative controls to reduce heat stress, medical surveillance, and provision of fluids and shady areas for rest breaks.
热应激是一种环境和职业危害因素，与一系列与热相关的疾病有关，包括热射病，可导致死亡。疾病预防控制中心（CDC）的国家职业安全与健康研究所（NIOSH）发布了热应激职业暴露限值的建议（1）。这些限值与美国政府工业卫生学家会议（ACGIH）的限值一致（2），规定了工人应暴露于的环境热（以湿球黑球温度[WBGT]衡量）和代谢热（即工作量）的最大组合。对于未适应热环境的工人、穿着阻碍散热的工作服的工人以及具有易患个人风险因素的工人，暴露限值较低（1,2）。这些限值已在实验环境中得到验证，但尚未在户外工作场所得到验证。为了确定 NIOSH 和 ACGIH 的暴露限值是否能保护工人，CDC 回顾性审查了 2011 年至 2016 年期间职业安全与健康管理局（OSHA）调查的 25 例户外职业性与热相关的疾病（14 例致命和 11 例非致命）。对于每起事件，OSHA 评估了个人风险因素，并估计了 WBGT、工作量和适应状态。在所有 14 例致命病例和 11 例非致命病例中，热应激均超过了暴露限值。对 25 例病例的 Heat Index 数据的分析表明，当无法获得 WBGT 时，85°F（29.4°C）的 Heat Index 筛查阈值可识别工作场所环境热的潜在危险水平。一旦超过暴露限值，就应采取保护措施。全面的与热相关的疾病预防计划应包括为新入职和未适应的长期工人制定适应计划（例如，在早期热浪期间），为工人和主管人员提供有关症状识别和急救的培训（例如，在医疗专业人员到达之前对疑似热射病患者进行积极冷却），采取工程和行政控制措施以减少热应激，进行医疗监测，并提供液体和阴凉休息区。
