臺中都會區PM2.5中多環芳香烴與金屬元素日夜之物化特性與來源解析及其對人體健康之風險

Abstract

多環芳香烴（PAHs）與金屬元素為PM2.5的重要組成，除了影響空氣品質，其對人體健康的潛在危害不僅可能造成呼吸道與心血管疾病，甚至具有致癌的風險。儘管過去已有許多研究探討PAHs或金屬元素之濃度、來源解析及健康風險，但同時針對PAHs與金屬探討來源導向的健康危害之研究較為稀少，可能會導致污染來源管制的不確定性。本研究於2022至2023年間在台中都會區進行PM2.5採樣，涵蓋四季並區分日間（08:00–20:00）與夜間（20:00–08:00）。16種PAHs以氣相層析質譜儀進行分析，而13種金屬元素則以電感耦合電漿質譜儀進行分析，並以正矩陣因子法鑑定污染來源與貢獻。此外，亦利用潛在來源貢獻因子、條件雙變量機率函數與HYSPLIT模型分析潛在來源主要貢獻區域。本研究結果PAHs總濃度介於1.47 – 10.53 ng m-3，金屬總濃度則為414.66 – 5046.21 ng m-3。PAHs主要來自工業排放 （29.6%）、交通排放 （24.9%）、生物質與煤炭燃燒 （21.8%）、重柴油車 （12.1%）與石油/油類揮發 （11.5%）；金屬則以交通/地殼來源 （32.3%）與生物質燃燒 （32.2%）為主，其餘為工業排放1 （11.2%）、工業排放2 （13.8%）、重油燃燒（7.9%）與煤炭燃燒（2.5%）。來源潛勢分析顯示在秋冬期間污染物的濃度與貢獻顯著受到中國、韓國及日本等鄰近國家之活動及長程傳輸作用影響。增量終生致癌風險(ILCR)分析結果顯示PAHs全年以工業排放為主要致癌來源，其中秋季日間與冬季日夜間之ILCR超過安全閾值 (10-6)；金屬致癌風險則是春夏以交通/地殼源為主，秋冬轉為煤炭燃燒貢獻顯著，總ILCR僅春夏季夜間低於10-6。研究結果顯示無論是 PAHs 或金屬其總致癌風險普遍呈現日間高於夜間的趨勢，此外金屬非致癌風險全年由交通/地殼源主導。此研究結果說明PAHs與金屬的主要污染來源及其主導健康風險的影響有所差異，應同時考量其時空變異性與污染源之貢獻，以利於更精準分析污染源對人體健康之影響，進而提供較精確且有效地空污管制策略。

Polycyclic aromatic hydrocarbons (PAHs) and metal elements are key components of PM2.5 with known toxic properties, potentially causing respiratory and cardiovascular diseases as well as cancer. Although previous studies have examined the concentration variations, source apportionment, and health risks of either PAHs or metals, research simultaneously addressing the sources and health impacts of both PAHs and metals remains limited. This study conducted PM2.5 sampling in the Taichung metropolitan area, covering four seasons and distinguishing between daytime (08:00–20:00) and nighttime (20:00–08:00) periods. Sixteen PAHs were analyzed using gas chromatography coupled with mass spectrometry, and thirteen metals were quantified using inductively coupled plasma mass spectrometry. Positive matrix factorization (PMF) was applied for source apportionment, along with potential source contribution function (PSCF), conditional bivariate probability function (CBPF), and HTSPLIT model to identify potential source regions. The results showed total PAH concentrations ranged from 1.47 to 10.53 ng m-3, while total metal concentrations from 414.66 to 5046.21 ng m-3. PAHs primarily originated from industrial emissions (29.6%), vehicular emissions (24.9%), biomass burning/coal combustion (21.8%), heavy-duty diesel vehicles (12.1%), and petroleum/oil volatilization (11.5%). For metals, traffic emissions/crustal materials (32.3%) and biomass burning (32.2%) were dominant, followed by two types of industrial emissions, heavy oil combustion, and coal combustion. Source origin analysis indicated that pollutant levels and contributions in autumn and winter were influenced by regional activities and long-range transport from neighboring countries such as China, Korea, and Japan. Incremental Lifetime Cancer Risk (ILCR) assessments showed that PAHs posed the highest carcinogenic risk from industrial emissions, with ILCR exceeding 10-6 during autumn daytime and winter day and night. For metals, traffic emissions/crustal sources dominated in spring and summer, while coal combustion became the main contributor in autumn and winter. Total CR was below 10-6 only at night in spring and summer. Both pollutants exhibited higher daytime carcinogenic risk. The noncarcinogenic risk of metals was consistently dominated by traffic emissions/crustal materials throughout the year. This study highlights distinct source contributions and health risks of PAHs and metals, emphasizing the need to consider spatiotemporal variability for more accurate risk assessments and more effective air quality and health protection strategies.