Near-road sampling of PM 2. 5 , BC, and fine-particle chemical components in Kathmandu Valley, Nepal

A significant contribution of vehicle-related emissions to air pollution in Kathmandu Valley, Nepal, persists throughout both the dry spring and monsoonal seasons. Despite lower overall PM2.5 concentrations during the monsoon, black carbon (BC) levels remained high, indicating strong vehicular influence year-round. The study, conducted using near-road sampling by volunteer traffic police officers at six major intersections in 2014, found that BC accounted for 39% of PM2.5 during the monsoon compared to 18% in spring, alongside increased contributions from crustal elements and heavy metals. Silica, calcium, aluminum, and iron were dominant elements in both seasons, with minimal spatial variation observed in PM2.5 and BC concentrations.

Shakya, K. M., Rupakheti, M., Shahi, A., Maskey, R., Pradhan, B., Panday, A., Puppala, S. P., Lawrence, M., & Peltier, R. E. (2017). Near-road sampling of PM _2. 5 , BC, and fine-particle chemical components in Kathmandu Valley, Nepal. Atmospheric Chemistry and Physics, 17(10), 6503–6516. https://doi.org/10.5194/acp-17-6503-2017