Hammond Duane, Garcia Alberto, Feng H Amy
Division of Applied Research and Technology, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 4676 Columbia Parkway, Cincinnati, OH 45226, USA.
Ann Occup Hyg. 2011 Jul;55(6):591-600. doi: 10.1093/annhyg/mer021. Epub 2011 May 19.
A utility-scale wind turbine blade manufacturing plant requested assistance from the National Institute for Occupational Safety and Health (NIOSH) in controlling worker exposures to styrene at a plant that produced 37 and 42 m long fiber-reinforced wind turbine blades. The plant requested NIOSH assistance because previous air sampling conducted by the company indicated concerns about peak styrene concentrations when workers entered the confined space inside of the wind turbine blade. NIOSH researchers conducted two site visits and collected personal breathing zone and area air samples while workers performed the wind turbine blade manufacturing tasks of vacuum-assisted resin transfer molding (VARTM), gelcoating, glue wiping, and installing the safety platform.
All samples were collected during the course of normal employee work activities and analyzed for styrene using NIOSH Method 1501. All sampling was task based since full-shift sampling from a prior Occupational Safety and Health Administration (OSHA) compliance inspection did not show any exposures to styrene above the OSHA permissible exposure limit. During the initial NIOSH site visit, 67 personal breathing zone and 18 area air samples were collected while workers performed tasks of VARTM, gelcoating, glue wipe, and installation of a safety platform. After the initial site visit, the company made changes to the glue wipe task that eliminated the need for workers to enter the confined space inside of the wind turbine blade. During the follow-up site visit, 12 personal breathing zone and 8 area air samples were collected from workers performing the modified glue wipe task.
During the initial site visit, the geometric means of the personal breathing zone styrene air samples were 1.8 p.p.m. (n = 21) for workers performing the VARTM task, 68 p.p.m. (n = 5) for workers installing a safety platform, and 340 p.p.m. (n = 14) for workers performing the glue wipe task, where n is the number of workers sampled for a given mean result. Gelcoating workers included job categories of millers, gelcoat machine operators, and gelcoaters. Geometric mean personal breathing zone styrene air samples were 150 p.p.m. (n = 6) for millers, 87 p.p.m. (n = 2) for the gelcoat machine operators, and 66 p.p.m. (n = 19) for gelcoaters. The geometric mean of the personal breathing zone styrene air samples from the glue wipe task measured during the follow-up site visit was 31 p.p.m. (n = 12).
The closed molding VARTM process was very effective at controlling worker exposures to styrene. Personal breathing zone styrene air samples were reduced by an order of magnitude after changes were made to the glue wipe task. The company used chemical substitution to eliminate styrene exposure during the installation of the safety platform. Recommendations were provided to reduce styrene concentrations during gelcoating.
一家公用事业规模的风力涡轮机叶片制造工厂请求美国国家职业安全与健康研究所（NIOSH）协助控制一家生产37米和42米长纤维增强风力涡轮机叶片工厂的工人接触苯乙烯的情况。该工厂请求NIOSH提供协助，因为公司之前进行的空气采样表明，当工人进入风力涡轮机叶片内部的受限空间时，对苯乙烯峰值浓度存在担忧。NIOSH研究人员进行了两次现场考察，并在工人执行风力涡轮机叶片制造任务（真空辅助树脂传递模塑（VARTM）、凝胶涂层、擦胶和安装安全平台）时收集了个人呼吸区和区域空气样本。
所有样本均在员工正常工作活动期间采集，并使用NIOSH方法1501分析苯乙烯。所有采样均基于任务，因为先前职业安全与健康管理局（OSHA）合规检查的全时采样未显示任何高于OSHA允许接触限值的苯乙烯接触情况。在NIOSH首次现场考察期间，在工人执行VARTM、凝胶涂层、擦胶和安全平台安装任务时，收集了67个个人呼吸区和18个区域空气样本。首次现场考察后，公司对擦胶任务进行了更改，消除了工人进入风力涡轮机叶片内部受限空间的必要性。在后续现场考察期间，从执行修改后擦胶任务的工人中收集了12个个人呼吸区和8个区域空气样本。
在首次现场考察期间，执行VARTM任务的工人个人呼吸区苯乙烯空气样本的几何平均值为1.8 ppm（n = 21），安装安全平台的工人为68 ppm（n = 5），执行擦胶任务的工人为340 ppm（n = 14），其中n是为给定平均结果采样的工人数量。凝胶涂层工人包括铣床工人、凝胶涂层机器操作员和凝胶涂层工等工种。铣床工人个人呼吸区苯乙烯空气样本的几何平均值为150 ppm（n = 6），凝胶涂层机器操作员为87 ppm（n = 2），凝胶涂层工为66 ppm（n = 19）。后续现场考察期间测量的擦胶任务个人呼吸区苯乙烯空气样本的几何平均值为31 ppm（n = 12）。
封闭式模塑VARTM工艺在控制工人接触苯乙烯方面非常有效。对擦胶任务进行更改后，个人呼吸区苯乙烯空气样本减少了一个数量级。公司在安装安全平台期间采用化学替代方法消除了苯乙烯接触。还提供了关于降低凝胶涂层期间苯乙烯浓度的建议。
