螺絲製造業勞工之油霧滴暴露濃度與粒徑分布特徵研究

Concentration and Particle Size Distribution of Oil Mists Exposed to Fastening Industry Workers

本研究針對螺絲製造業成型、搓牙及熱處理等三個製程區作業勞工，以個人可吸入性氣膠採樣器實施八小時個人採樣（n＝ 17, 11, 6），並同時針對其作業區域實施粒徑分布採樣（n ＝ 4, 4, 4）以探討勞工油霧滴之暴露情形與粒徑分布特徵。研究發現可吸入性油霧滴暴露情形依序為搓牙（2.11mg/m3 ）＞成型（1.58mg/m3 ）＞熱處理（0.0801mg/m3 ），唯均小於目前PEL-TWA及TLV-TWA之規定（5mg/m3 ）。三製程區作業勞工暴露之油霧滴發現均呈雙峰分布，其中細粒徑油霧滴，主要由金屬加工用油受熱揮發再凝結而成，其氣動粒徑介於 0.310~0.501µm 之間。粗粒徑油霧滴，主要由機械或螺絲與金屬加工用油碰撞噴濺而成，其氣動粒徑介於 8.16~13.0µm 之間。三製程區空氣中細／粗粒徑油霧滴之重量濃度比值分別為 2.77，1.65，及 1.20。但若依粒徑分布結果推估油霧滴之呼吸道沉降情形，可發現三製程區作業勞工暴露主要集中在肺泡區（佔 66.9~77.9％），次為頭區（佔 14.5~19.1％），最後為氣管與支氣管區（佔 7.56~15.8％）。其中成型及搓牙勞工可呼吸性油霧滴推估暴露濃度高達 1.34mg/m3 及 1.40mg/ m3 ，已明顯大於可能造成肺部傷害之 0.20mg/m3 ，顯示應針對細粒徑部分之油霧滴使勞工佩戴有效防護具，或對作業場所採取合適之工程控制方法，以防止油霧滴對勞工之健康危害。

The present study was designed to assess the concentration and particle size distribution of oil mist exposure of workers in the fastening industry. An IOM personal inhalable aerosol sampler was used to collect 17, 11, and 6 personal oil mist samples from workers in the forming, tapping, and heat treatment process, respectively. For each process, particle-size-segregating samples of oil mist were collected simultaneously by a modified cascade impactor, with a total of 4 samples being obtained. Results showed that the concentrations of worker exposure in the three processes were: tapping (2.11mg/m3) > forming (1.58mg/m3) > heat treatment (0.0801mg/m3). These concentrations were lower than the current timeweighted- average threshold limit value (TLV-TWA=5mg/m3) and time-weighted-average permissible exposure limit value (PEL-TWA=5mg/m3) of oil mist. The particle size distribution of oil mist from the three processes was consistent with bimodal distribution. The fraction of fine particles, which were formed by the evaporation and condensation of metalworking fluids, was found with aerodynamic diameters (dae) of 0.310~0.501μm. The coarse fraction was formed by the impaction of metalworking fluids with tools and fasteners, and had a dae of 8.16~13.0μm.. The concentration ratios of fine/coarse oil mists from the three processes were 2.77 for tapping, 1.65 for forming, and 1.20 for heat treatment. The fractions of oil mist exposure from the three processes to different areas of workers’ respiratory tracts were: alveolar (66.9-77.9﹪) > head (14.5-19.1﹪) > trachea bronchial (7.56-15.8﹪). The estimated concentrations of respirable oil mist for workers in the forming and tapping processes were 1.34mg/m3 and 1.40mg/m3, which were higher than the concentration known for“ increased risk of pulmonary injury” (0.20mg/m3). The results warrant the adoption of suitable methods of engineering control or personal protective equipment to reduce the exposure of workers, especially for the fine fraction.