Spatiotemporal variability, atmospheric chemistry implications and health risk assessment of ambient volatile organic compounds in Central India.

Twenty-one volatile organic compounds (VOCs) that are markers for anthropogenic and biogenic emission sources were quantified in and around the city of Raipur, Chhattisgarh state in central India from November 2021 to February 2022 and from April to June 2022. Spatiotemporal VOC patterns, implications for atmospheric reactivity and associated health risks are investigated. Six monitoring sites represented the urban background, an industrial area, a commercial center, a residential neighbourhood, a refuelling station, and a traffic junction. Ambient air was drawn through Tenax sorbent tubes followed by analysis using Thermal- Desorption Gas Chromatography Triple Quadrupole Mass spectrometry (TD-GC-MS/MS). Benzene (BeZ) concentrations were ~ 3-8 times higher than the Indian National Ambient Air Quality Standards of 5 µg-m^-3. Toluene achieved the highest average concentration of 70.22 ± 10.20 µg-m^-3 near the heavily-travelled roadway. The sum of VOCs (Σ₂₁VOCs) was highest near the refuelling station, followed the roadway, the industrial area, the commercial area and the residential neighbourhood. Low concentrations were found at the background site. Toluene /Benzene ratios indicate that the vehicular exhaust is the prevailing source of ambient VOCs. Ozone Formation Potential calculations indicate isomers of xylene and toluene are main contributor to ozone formation. Lifetime cancer risks (LTCR) values for both children and adults exceeded the recommended values of USEPA (10^-6) and the WHO (10^-5).