He Qiusheng, Yan Yulong, Zhang Yanli, Wang Xinming, Wang Yuhang
College of Environment and Safety, Taiyuan University of Science and Technology, Taiyuan, 030024, China,
Environ Monit Assess. 2015 Jun;187(6):359. doi: 10.1007/s10661-015-4582-7. Epub 2015 May 16.
China is the largest coke producer and exporter in the world, and it has been a major concern that large populations of coke workers are exposed to the associated air pollutants such as volatile organic compounds (VOCs). This study aimed to preliminarily quantify the potential exposure to VOCs emitted from two representative coking plants and assess the potential health risks. Air samples from various stages of coking were collected from the topside of coke ovens and various plant areas and then analyzed for benzene, toluene, ethylbenzene, and xylene (BTEX). The time-weighted average (TWA) concentrations were used to quantify the coke oven emission (COE). The TWA concentrations for benzene were 705.6 and 290.4 μg m(-3) in plant A and plant B, respectively, which showed a higher exposure level than those reported in other countries. COE varied on the topside of coke ovens during charging and pushing processes, from 268.3 to 1197.7 μg m(-3) in plant A and 85.4-489.7 μg m(-3) in plant B. Our results indicate that benzene exposure from the diffusion of tar distillation also exerts significant health risks and thus should also be concerned. Charging and pushing activities accounted for nearly 70 % of benzene dose at the topside, and the benzene exposure risks to the coke oven workers in China were higher than those reported by US EPA. Compared to the reported emission sources, the weight-based ratios of average benzene to toluene, ethylbenzene, and xylene in different COE air samples showed unique characteristic profiles. Based on the B/T ratios from this work and from literatures on several major cities in northern China, it was evident that COE contributes significantly to the severe pollution of VOCs in the air of northern China. Future more rigorous studies are warranted to characterize VOC emission profiles in the stack gas of the coking processes in China.
中国是世界上最大的焦炭生产国和出口国，大量焦炭工人暴露于挥发性有机化合物（VOCs）等相关空气污染物中，这一直是人们主要关注的问题。本研究旨在初步量化两家代表性焦化厂排放的VOCs潜在暴露量，并评估潜在健康风险。从焦炉顶部和厂区各个区域收集焦化不同阶段的空气样本，然后分析苯、甲苯、乙苯和二甲苯（BTEX）。采用时间加权平均（TWA）浓度来量化焦炉排放（COE）。A厂和B厂苯的TWA浓度分别为705.6和290.4μg m(-3)，高于其他国家报告的暴露水平。在装料和推焦过程中，焦炉顶部的COE有所不同，A厂为268.3至1197.7μg m(-3)，B厂为85.4 - 489.7μg m(-3)。我们的结果表明，焦油蒸馏扩散产生的苯暴露也会带来重大健康风险，因此也应受到关注。装料和推焦活动占顶部苯剂量的近70%，中国焦炉工人的苯暴露风险高于美国环境保护局报告的水平。与报告的排放源相比，不同COE空气样本中苯与甲苯、乙苯和二甲苯的重量比呈现出独特的特征分布。基于本研究以及中国北方几个主要城市文献中的B/T比值，很明显COE对中国北方空气中VOCs的严重污染有显著贡献。未来有必要开展更严格的研究来表征中国焦化过程烟囱气体中的VOC排放特征。
