垃圾暫置場挖掘作業人員之粉塵、重金屬、硫醇類氣體與生物氣膠暴露特性

Exposure characteristics of dust, heavy metals, thiols, and bioaerosols among excavator operators in municipal solid waste temporary storage sites

目標：國內垃圾處理受限於焚化爐歲修或量能不足，導致「垃圾暫置場」成為常態性運作場所。挖掘機駕駛為此類場所主要作業人員，面臨粉塵、生物氣膠與有機腐敗氣體之複合暴露風險。本研究旨在調查不同型態垃圾暫置場中，挖掘作業人員於總粉塵、可呼吸性粉塵、重金屬、生物氣膠及異味來源（硫醇類）之暴露特性。方法：選取國內5處具代表性之垃圾暫置場（代號A-E），涵蓋長期堆置型與短期轉運型場域。針對所有場域進行作業環境及駕駛艙內之「總粉塵」、「可呼吸性粉塵」、「硫醇類」及「生物氣膠」採樣，並分析粉塵中8種重金屬成分。利用Mann-Whitney U檢定比較不同操作型態之暴露差異。結果：粉塵與重金屬部分，駕駛艙內總粉塵（0.33-0.62 mg/m3）與可呼吸性粉塵濃度均低於我國勞工作業場所容許暴露標準，重金屬以鐵（Fe）為主，鎘（Cd）多數未檢出。然而，生物氣膠在駕駛艙內濃度仍達103 CFU/m3數量級，且細菌與真菌濃度皆高於室內空氣品質標準建議值。統計檢定證實，關窗作業之粉塵室內/室外濃度比值（I/O Ratio, 0.74±0.08）顯著低於開窗作業（0.89±0.04, p < 0.05），顯示具阻絕效果；但在氣體部分，關窗之A場域駕駛艙內檢出硫化氫（0.0035 ppmv），開窗之B場域則未檢出。結論：垃圾暫置場之粒狀污染物雖合規，但高濃度生物氣膠為潛在危害。現行標準駕駛艙雖能有效阻絕粉塵（關窗I/O顯著較低），但因濾網缺乏濾除氣態有機物的功能，導致關窗時硫化氫氣體於艙內累積。建議未來應將空調濾網升級為具化學吸附功能之複合濾材，以解決氣態與粉塵問題。

Objectives: Because of the need for ongoing maintenance for incineration facilities and insufficient processing capacity in Taiwan, municipal solid waste (MSW) temporary storage sites have become widespread in the region. Excavator operators at these sites are exposed to a complex mix of dust, bioaerosols, and volatile organic compounds. The present study investigated these operators’exposure to total dust, respirable dust, heavy metals, bioaerosols, and odorous thiols. Methods: Five representative MSW temporary storage sites were selected. Air samples were collected from inside excavator cabins and from fixed locations around the storage sites. Concentrations of total dust, respirable dust, and bioaerosols were measured, and dust samples were analyzed for eight heavy metals. Additionally, concentrations of thiols, such as hydrogen sulfide, were measured at sites with reported odor complaints. The Mann–Whitney U test was used to compare exposure levels between open-window and closed-window operation modes. Results: The concentrations of total dust (0.33–0.62 mg/m3), respirable dust, and heavy metals inside the cabins were all within the permissible exposure limits specified by the Taiwanese government. However, bioaerosol concentrations were high (103 CFU/m3), with bacteria and fungi levels exceeding indoor air quality recommendations. Statistical analysis confirmed that closed-window operations had significantly lower indoor/outdoor dust ratios (0.74±0.08) than open-window operations did (0.89±0.04, p < .05), indicating effective isolation. Conversely, for gaseous pollutants, hydrogen sulfide was detected only inside closed cabins (0.0035 ppmv). Conclusions: Although concentrations of total dust, respirable dust, and heavy metals were within Taiwan’s permissible exposure limits, bioaerosols were not, indicating a potential hazard. The cabins effectively blocked dust (as evidenced by lower indoor/outdoor ratios); however, air filters lack the capability to remove gaseous organic compounds, leading to the accumulation of hydrogen sulfide when windows are closed. Combined particulate and gas filters capable of absorbing chemicals should be employed to simultaneously address dust isolation and gas removal.