Highly Volatile POPs in Urban Air across Asia and Africa: Dominance of Volatile Methylsiloxanes

Highly volatile persistent organic pollutants (HV-POPs)
are characterized
by high volatility, environmental persistence, bioaccumulative potential,
toxicity, and ability for long-range transport, posing environmental
and health concerns. However, research on HV-POPs remains limited,
particularly in rapidly urbanizing regions, constraining understanding
of their sources, environmental fate, and risks. This study investigated
52 HV-POPs, including Stockholm Convention-listed POPs like hexachlorobutadiene
(HCBD) and hexa-/pentachlorobenzene (HCB/PeCB), and nonlisted HV-POPs
such as volatile methylsiloxanes (VMS) and chlorinated nitrobenzenes
(CNBs), using active air samplers in six major cities across Asia
and Africa. The median total concentrations of HV-POPs were highest
in Guangzhou (351 ng/m3), followed by Kuala Lumpur (167
ng/m3), Accra (82.4 ng/m3), Dhaka (73.3 ng/m3), Nairobi (44.9 ng/m3), and Islamabad (33.5 ng/m3). VMS dominated at all sites, accounting for 84 ± 18%
of total HV-POPs, up to 2–5 orders of magnitude higher than
other compounds. Source analysis showed VMS emissions in Guangzhou
were mainly from industrial activities, while in the other cities,
they were from usage of personal care products. Inhalation risk assessments
indicated negligible noncarcinogenic and carcinogenic risks at all
sites. This study provides the first multiregional HV-POPs data set
in urban air, supporting chemical risk assessment efforts and broader
international regulatory initiatives.

高挥发性持久性有机污染物（Highly volatile persistent organic pollutants, HV-POPs）具有高挥发性、环境持久性、生物累积潜力、毒性及长距离迁移能力，对环境与人类健康构成潜在威胁。然而，当前针对HV-POPs的研究仍较为匮乏，尤其是在快速城市化地区，这限制了学界对其来源、环境归趋与风险的认知。本研究针对52种HV-POPs展开调查，涵盖《斯德哥尔摩公约》（Stockholm Convention）所列持久性有机污染物，如六氯丁二烯（hexachlorobutadiene, HCBD）与六/五氯苯（hexa-/pentachlorobenzene, HCB/PeCB），以及非公约列管的HV-POPs，例如挥发性甲基硅氧烷（volatile methylsiloxanes, VMS）与氯化硝基苯（chlorinated nitrobenzenes, CNBs）；研究采用主动空气采样器，在亚洲与非洲的6座主要城市开展采样工作。HV-POPs的总浓度中位数以广州最高（351纳克/立方米），其后依次为吉隆坡（167纳克/立方米）、阿克拉（82.4纳克/立方米）、达卡（73.3纳克/立方米）、内罗毕（44.9纳克/立方米）与伊斯兰堡（33.5纳克/立方米）。挥发性甲基硅氧烷（VMS）在所有采样点位均占主导地位，占HV-POPs总浓度的84±18%，其浓度较其他化合物高出2至5个数量级。源解析结果表明，广州地区的VMS排放主要源于工业活动，而其他城市的VMS排放则来自个人护理产品的使用。吸入风险评估结果显示，所有采样点位的非致癌与致癌风险均处于可忽略水平。本研究首次构建了多区域城市大气HV-POPs数据集，可为化学品风险评估工作及更广泛的国际监管行动提供支撑。