Summer-Time Monitoring And Source Apportionment Study Of Both Coarse, Fine, And Ultra-Fine Particulate Pollution In Eastern Himalayan Darjeeling: A Hint To Health Risk During Peak Tourist Season

The present study focuses on the elemental characterization and contribution of prominent sources of particulate matter (PM) in Darjeeling, the high-altitudinal eastern Himalayan station. The concentration of PM₁₀ and PM_2.5 was exceeded the National Ambient Air Quality Standards (NAAQS) for 72% and 83% of the sampling days, respectively. Since the World Health Organization or other government organizations has not set any standards for PM₁, the standards of PM₁₀ and PM_2.5 were considered as benchmarks. The concentration of PM₁ exceeded the NAAQS for PM₁₀ and PM_2.5 on 57% and 85% of the days, respectively. The elemental characterization using wavelength dispersive X-ray fluorescence (WD-XRF) technique identified 21 elements with the dominance of Si, Na, B, Ba, Al, and K in PM₁₀; while, Al, N, and B in PM_2.5 and PM₁. Principal component analysis depicted that biomass burning, fossil fuel combustion, crustal/soil dust, and industrial emissions were identified as primary contributors to PM₁₀; PM_2.5 was substantially attributed to industrial emissions, agricultural activities, biomass burning, vehicular activities and natural sources. Additionally, natural sources and anthropogenic activities like vehicular, agricultural, and industrial emissions, and combustion were identified as the major sources of PM₁ in Darjeeling. The findings of this study could potentially raise awareness among researchers and policymakers, prompting them to develop sustainable strategies in hill regions across the globe.