Ambient air quality in the Kathmandu Valley, Nepal, during the pre-monsoon: concentrations and sources of particulate matter and trace gases

Aerosol liquid water content and gas-aerosol phase partitioning of NH3, HNO3, and HCl in the Kathmandu Valley vary significantly with diurnal temperature and humidity changes. The study identified multiphase halogen-radical chemistry involving chlorine (Cl) and bromine (Br), which impacts regional air quality. Molecular markers for primary and secondary sources indicate that garbage burning contributes up to three times more than previously estimated, while biomass burning remains a significant source of organic carbon in PM2.5. Anthropogenic combustion sources, including biomass burning, garbage burning, and fossil fuel combustion, are the greatest contributors to PM pollution in the valley.

Islam, Md. R., Jayarathne, T., Simpson, I. J., Werden, B., Maben, J., Gilbert, A., Praveen, P. S., Adhikari, S., Panday, A. K., Rupakheti, M., Blake, D. R., Yokelson, R. J., DeCarlo, P. F., Keene, W. C., & Stone, E. A. (2020). Ambient air quality in the Kathmandu Valley, Nepal, during the pre-monsoon: concentrations and sources of particulate matter and trace gases. Atmospheric Chemistry and Physics, 20(5), 2927–2951. https://doi.org/10.5194/acp-20-2927-2020