The oxidative potential (OP) of particulate matter (PM) is a major driver of PM-associated health effects. In India, the emission sources defining PM-OP, and their local/regional nature, are yet to be established. Here, to address this gap we determine the geographical origin, sources of PM, and its OP at five Indo-Gangetic Plain sites inside and outside Delhi. Our findings reveal that although uniformly high PM concentrations are recorded across the entire region, local emission sources and formation processes dominate PM pollution. Specifically, ammonium chloride, and organic aerosols (OA) from traffic exhaust, residential heating, and oxidation of unsaturated vapors from fossil fuels are the dominant PM sources inside Delhi. Ammonium sulfate and nitrate, and secondary OA from biomass burning vapors, are produced outside Delhi. Nevertheless, PM-OP is overwhelmingly driven by OA from incomplete combustion of biomass and fossil fuels, including traffic. These findings suggest that addressing local inefficient combustion processes can effectively mitigate PM health exposure in northern India.

颗粒物 (PM) 的氧化潜力 (OP) 是 PM 相关健康影响的主要驱动因素。在印度，定义 PM-OP 的排放源及其当地/区域性质尚未确定。在这里，为了解决这一差距，我们确定了德里内外五个印度恒河平原地点的 PM 的地理起源、来源及其 OP。我们的研究结果表明，尽管整个地区的 PM 浓度一致较高，但当地的排放源和形成过程主导着 PM 污染。具体来说，氯化铵和交通尾气、住宅供暖产生的有机气溶胶 (OA) 以及化石燃料不饱和蒸气的氧化是德里内的主要 PM 来源。硫酸铵和硝酸铵以及来自生物质燃烧蒸气的二次OA均在德里以外生产。然而，PM-OP 绝大多数是由生物质和化石燃料（包括交通）不完全燃烧产生的 OA 驱动的。这些发现表明，解决当地低效燃烧过程可以有效减轻印度北部PM健康暴露。