Emission Characteristics and Cancer Risks of Polycyclic Aromatic Hydrocarbon Emissions from Diesel-fueled Vehicles Complying with Recent Regulations
Emission Characteristics and Cancer Risks of Polycyclic Aromatic Hydrocarbon Emissions from Diesel-fueled Vehicles Complying with Recent Regulations
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DOI：
10.1248/jhs.56.200
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发表时间：
2010
影响因子：
--
通讯作者：
Kiriko Kashiwakura;K. Sakamoto
中科院分区：
文献类型：
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作者：
Kiriko Kashiwakura;K. Sakamoto
最近的法规进一步降低了受管制物质的允许含量，从而减少了柴油车的多环芳烃 (PAH) 排放。我们分析了符合这些严格法规的三辆柴油车冷启动或热启动测试循环中 13 种 PAH 的排放量，并根据毒性当量因子 (TEF) 估算了癌症风险。两辆车配备了氧化催化剂，一辆配备了尿素选择性催化还原（SCR）系统。符合标准的车辆的大多数 PAH 排放量低于其他没有后处理装置的柴油车辆。三款车中萘（Naph）的排放量最高（2.92-376微克/公里）；按质量计算，它占所有 PAH 排放量的 51.1-84.8%（平均值 73.0%，S.D.±12.2%）。然而，在 SCR 系统中，萘烷排放物可能在收集过程中分解，因为替代物的回收率较低，这表明 SCR 系统废气中存在特定的反应物质。排放控制装置的应用降低了多环芳烃排放的癌症风险。二环多环芳烃 (Naph) 的大多数苯并[a]芘当量 (B[a]Peq) 排放量或苯并[a]芘等五环多环芳烃的总排放量均大于其他环多环芳烃。尽管 Naph 的 TEF 较低 (0.001)，但它在总 B[a]Peq 中所占比例很高（26-74%；平均值 54%，S.D.±15%）。由于减排技术的进步，具有高癌症风险的颗粒物五环多环芳烃的含量正在减少。因此，Naph 作为气态 PAH 对 TEF 确定的致癌风险的相对贡献正在增加。
Polycyclic aromatic hydrocarbon (PAH) emissions from diesel vehicles have been reduced by recent regulations further dropping the permissible levels of regulated substances. We analyzed emissions of 13 PAHs from cold- or hot-start test cycles in three diesel vehicles complying with these stringent regulations, and we estimated cancer risk in terms of toxic equivalency factors (TEFs). Two vehicles were equipped with oxidation catalysts and one with a urea-selective catalytic reduction (SCR) system. Most PAH emissions were lower from the compliant vehicles than from other diesel vehicles with no aftertreatment devices. For the three vehicles, naphthalene (Naph) was emitted at the highest rate (2.92-376 μg/km); by mass it constituted 51.1-84.8% (mean 73.0%, S.D.±12.2%) of all PAH emissions. However, in the SCR system, Naph emissions probably decomposed during collection, because the percentage recoveries of surrogate were low, suggesting the presence of specific reactive substances in the SCR system exhaust. The cancer risk of PAH emissions was reduced by application of the emission-control devices. Most benzo[a]pyrene-equivalent (B[a]Peq) emissions of two-ring PAHs (Naph) or total emissions of five-ring PAHs like benzo[a]pyrene were greater than those of other-ring PAHs. Although Naph has a low TEF (0.001), it constituted a high proportion of the total B[a]Peq (26-74%; mean 54%, S.D.±15%). The contents of particulate five-ring PAHs, which pose high cancer risks, are decreasing because of improvements in emissions-reduction technology. Hence, the relative contribution of Naph as a gaseous PAH to the TEF-determined risk of carcinogenesis is increasing.