Spatial and Temporal Variability of PM_2.5, PM₁₀ and BC Aerosols over Tropical Megacity Bengaluru, India

Abstract

PM_2.5, PM₁₀ mass levels at six and BC levels at one station were monitored at the tropical megacity, Bengaluru, India, for the year 2019. The annual average levels of PM_2.5, PM₁₀ and BC were 31, 73 and 2.72 µg/m³ respectively. PM_2.5 levels were within the Indian National Ambient Air Quality Standard (INAAQS) value of 40 µg/m³ whereas that of PM₁₀ exceeded INAAQS level of 60 µg/m³ for the year 2019 for all six stations. The season-wise diurnal variability of PM and BC shows bimodal peaks, first one in the morning and the second one in the late evening hours in all the stations. These peaks correspond to rush traffic hours and lower PBL height. The correlation analysis of PM and BC with meteorological parameters is presented. The data are also analysed for the Deepavali festival. The PM_2.5 levels in festival have doubled, PM₁₀ levels increased by more than 50 %, while BC showed marginal increase. Further, the night-time levels of PM and BC were higher than the daytime during the festival. The health risk assessment using Air Q+ for the city of Bengaluru for 2019 shows highest PM exposure risk to ischemic heart disease.