作業場所原料與空氣粉塵所含結晶型游離二氧化矽之相關性探討

An Investigation of Correlation between Crystalline Free Silica Contents in Raw Materials and Those in Airborne Dusts at Workplaces

本研究針對製程大量使用石砂土原料，且具潛在結晶型游離二氧化矽高暴露的鑄造業、陶瓷業、玻璃製造業，探討其原料中結晶型游離二氧化矽比例與作業場所空氣中粉塵之結晶型游離二氧化矽比例之相關性。
本研究於2020年間，針對三種行業使用我國建議方法（CLA4003及4004）進行區域之可呼吸性粉塵、總粉塵及個人可呼吸性粉塵之結晶型游離二氧化矽採樣分析。現場共採集162個樣品（包括26個個人樣品及136個區域樣品），並另分析各廠原料樣品中結晶型游離二氧化矽的含量比例。
鑄造業、陶瓷業、玻璃製造業之原料樣品結晶型游離二氧化矽之比例平均值（±標準差）分別為44.41±9.41％、14.99±5.91％與56.95±17.48％、作業場所區域總粉塵結晶型游離二氧化矽之比例平均值（±標準差）分別為23.61±11.23％、54.93±13.15％與35.97±18.36％、及作業場所區域可呼吸性粉塵結晶型游離二氧化矽之比例平均值（±標準差）分別為20.58±11.41％、60.04±17.19％與61.38±21.93％。各廠原料中結晶型游離二氧化矽比例與對應之空氣中平均結晶型游離二氧化矽（總粉塵與可呼吸性粉塵）濃度、空氣粉塵中結晶型游離二氧化矽比例均無統計上顯著之相關性。本研究發現各廠原料之粒徑分布中位數（D50）差異頗大，如考慮現場粉塵樣品採集之粒徑特性及現場粉塵分布之不均勻特性，這些因素均可導致空氣樣品中粉塵特性與原料中不同。
雖然相關性統計之結果可受到樣本數及採樣誤差之影響，但本研究發現各廠內粉塵濃度及樣品中所含之結晶型游離二氧化矽百分比之變異性均大，因此，單一數值（原料中結晶型游離二氧化矽之比例）與多變之現場暴露濃度或樣品中結晶型游離二氧化矽之比例間，勢必無法呈現良好之相關性。

This study investigated the correlation between the proportion of crystalline free silica in raw materials and the proportion of crystalline free silica in airborne dust in workplaces in the foundry, ceramics, and glass manufacturing industries, which had potential high exposures to crystalline free silica due to the extensive use of sand and gravel raw materials in their processes.
In 2020, this study employed Taiwan's recommended methods (CLA4003 and 4004) to evaluate crystalline free silica exposure in three industries. The researchers collected 162 samples (26 personal samples and 136 regional samples) to analyze regional respirable dust, total dust, and personal respirable dust for crystalline free silica content. Additionally, they analyzed the crystalline free silica content in raw materials from each factory to identify potential exposure sources.
The average proportions (±standard deviation) of crystalline free silica in raw material samples from the foundry, ceramics, and glass manufacturing industries are 44.41±9.41%, 14.99±5.91%, and 56.95±17.48%, respectively. In terms of regional total dust crystalline free silica, the proportions are 23.61±11.23%, 54.93±13.15%, and 35.97±18.36%, respectively. For regional respirable dust crystalline free silica, the proportions are 20.58±11.41%, 60.04±17.19%, and 61.38±21.93%, respectively. No statistically significant correlation was found between the crystalline free silica proportion in each factory's raw materials and the corresponding average concentration of crystalline free silica in the air (total dust and respirable dust) or the proportion of crystalline free silica in the dust itself. This study revealed a significant difference in the median particle size distribution (D50) of raw materials across factories. Considering the particle size characteristics during on-site dust sample collection and the inherent non-uniformity of dust distribution within workplaces, these factors can lead to discrepancies between the dust characteristics in air samples and those in the raw materials.
While correlation statistics can be susceptible to sample size and sampling errors, this study revealed high variability in both dust concentration and the percentage of crystalline free silica within each factory. Consequently, a single value (proportion of crystalline free silica in raw materials) may not adequately capture the complex relationship with the multifaceted exposure concentrations and the variable crystalline free silica content observed in workplace samples.