Variability in air quality, ozone formation potential by VOCs, and associated air pollution attributable health risks for Delhi's inhabitants†

The present long-term study has been conducted with dual objectives: firstly, to monitor the spatio-temporal variation of ambient air quality parameters and secondly, to evaluate the impact of air pollutants on the Delhi population. Five years (January 2019 to December 2023) of data of six key pollutants (PM₁₀, PM_2.5, NO₂, O₃, Benzene, and Toluene) were collected by continuous ambient air quality monitoring stations, obtained from the Central Pollution Control Board portal. The impact of air pollutants on human health was assessed using different indices and the AirQ+ model developed by the World Health Organization (WHO). Additionally, the ozone formation potential (OFP) of benzene and toluene was evaluated. The findings of the study revealed that the concentrations of PM₁₀ and PM_2.5 exceeded both national and global guidelines across all the sites throughout the study period. Notably, industrial sites were classified as the severe category according to the National Air Quality Index. At industrial sites, the OFP of volatile organic compounds (VOCs) was observed to be higher in comparison to commercial sites. The AirQ+ model analysis in the health risk assessment indicated a strong association between PM₁₀ exposure and mortality from respiratory (91.36%) and chronic bronchitis (90.85%) diseases. Additionally, long-term PM_2.5 exposure was linked to an increased risk of stroke (65%) and circulatory (63.83%) mortality.