By Qian Zhang, UL Research Institutes
Air pollution in India has been a severe issue and is potentially associated with 1.67 million deaths every year. To reduce particulate matter (PM) pollution, it is important to understand the sources of PM and the health impact of PM associated with each source. This recently published paper by Bhattu et al. investigated the chemical composition of PM collected from 5 sites in northern India during warm and cold seasons. In addition, this study used oxidative potential (OP), the capability of PM to generate reactive oxygen species, as the measure of health effects of PM and links OP to each identified source.
On average, cold season showed higher PM2.5 concentration than warm season, with organic aerosol (OA) contributing to approximately 50% of the mass. The composition of OA was identified using LToF-AMS and EESI-LToF-MS and further analyzed with positive matrix factorization. OA associated with vehicular exhaust and cooking emissions and their secondary OA were higher at Delhi sites. Emissions from combustion of biomass and high nitrogen-containing compounds, and their secondary emissions appeared higher during cold season due to local residential heating. OP was assessed using acellular assays and linked to its main driving sources using a multiple linear regression model. OP per volume of sampled air (OPv) was found higher in sites outside of Delhi and during cold season. Intrinsic OP (OP per aerosol mass, OPm) was dominated by organics from combustion emissions and their oxidation products with secondary OA from urban emissions as the predominant contributor.
Overall, this study shows that while inorganic aerosol contributed about half of PM2.5 mass, OP seemed to be overwhelmingly driven by primary and secondary OA from local combustion. This study points to incomplete combustion as the major source of health-related PM, which helps policymakers to further design PM control strategies.
Read more in the literature:
Bhattu, D., Tripathi, S.N., Bhowmik, H.S. et al. Local incomplete combustion emissions define the PM2.5 oxidative potential in Northern India. Nat Commun 15, 3517 (2024). https://doi.org/10.1038/s41467-024-47785-5
This Issue’s Newsletter Committee:
Editor | Dong Gao, Yale UniversitySenior Assistant Editor | Sarah Petters, University of California, RiversideJunior Assistant Editor | Lindsay Yee, University of California, BerkeleyGuest Contributor | Qian Zhang, UL Research Institute