Phanprasit Wantanee, Rittaprom Kannikar, Dokkem Sumitra, Meeyai Aronrag C, Boonyayothin Vorakamol, Jaakkola Jouni J K, Näyhä Simo
Dept. of Occupational Health and Safety, Faculty of Public Health, Mahidol University, Bangkok, Thailand.
Aisin Takaoka Asia Co. Ltd., Bangkok, Thailand.
Saf Health Work. 2021 Mar;12(1):119-126. doi: 10.1016/j.shaw.2020.09.008. Epub 2020 Sep 25.
During the period 2001 to 2016, the maximum temperatures in Thailand rose from 38-41C to 42-44C. The current occupational heat exposure standard of Thailand issued in 2006 is based on wet bulb globe temperature (WBGT) defined for three workload levels without a work-rest regimen. This study examined whether the present standard still protects most workers.
The sample comprised 168 heat acclimatized workers (90 in construction sites, 78 in foundries). Heart rate and auditory canal temperature were recorded continuously for 2 hours. Workplace WBGT, relative humidity, and wind velocity were monitored, and the participants' workloads were estimated. Heat-related symptoms and signs were collected by a questionnaire.
Only 55% of the participants worked in workplaces complying with the heat standard. Of them, 79% had auditory canal temperature ≤ 38.5C, compared with only 58% in noncompliant workplaces. 18% and 43% of the workers in compliant and noncompliant workplaces, respectively, had symptoms from heat stress, the trend being similar across all workload levels. An increase of one degree (C) in WBGT was associated with a 1.85-fold increase (95% confidence interval: 1.44-2.48) in odds for having symptoms.
Compliance with the current occupational heat standard protects 4/5 of the workers, whereas noncompliance reduces this proportion to one half. The reasons for noncompliance include the gaps and ambiguities in the law. The law should specify work/rest schedules; outdoor work should be identified as an occupational heat hazard; and the staff should include occupational personnel to manage heat stress in establishments involving heat exposure.
在2001年至2016年期间，泰国的最高气温从38 - 41摄氏度升至42 - 44摄氏度。泰国2006年发布的现行职业热暴露标准是基于针对三种工作负荷水平定义的湿球黑球温度（WBGT）制定的，且没有工作休息制度。本研究调查了现行标准是否仍能保护大多数工人。
样本包括168名热适应工人（90名在建筑工地，78名在铸造厂）。连续记录心率和耳道温度2小时。监测工作场所的WBGT、相对湿度和风速，并估算参与者的工作量。通过问卷收集与热相关的症状和体征。
只有55%的参与者在符合热标准的工作场所工作。其中，79%的人耳道温度≤38.5摄氏度，而在不符合标准的工作场所这一比例仅为58%。在符合标准和不符合标准的工作场所中，分别有18%和43%的工人出现热应激症状，所有工作负荷水平的趋势相似。WBGT每升高1摄氏度，出现症状的几率增加1.85倍（95%置信区间：1.44 - 2.48）。
遵守现行职业热标准可保护五分之四的工人，而不遵守则将这一比例降至二分之一。不遵守的原因包括法律中的漏洞和含糊之处。法律应明确工作/休息时间表；应将户外工作确定为职业热危害；并且工作人员应包括职业人员，以管理涉及热暴露场所的热应激。
