Vertical Measurement of PM 2.5 and PM 10 in Street Canyons and Cohort Health Risk Estimation at Chennai,South India

Abstract

High-rise structures in urban regions create street canyons (SCs), which are hot-spots of air pollution, thereby posing human health risks due to exposure to high concentrations. In this concern, particulate matters (PMs: PM_2.5 and PM₁₀) were investigated in non-street canyon (NSC), SC, and street canyon with viaduct (SCV) at three heights above ground level at Chennai. NSC witnessed increasing concentrations of both PMs with increase in height. In SC, the vertical concentrations of PM_2.5 and PM₁₀ were increasing and decreasing with height, respectively. However, SCV recorded improper vertical trend with height. The statistical analysis shows a strong influence of wind speed and ambient temperature over the vertical trend of PMs, in addition to street geometry. The hazard quotient values for infants and senior citizens were two folds higher in SC and SCV than in NSC. Cancer risk estimates of PM_2.5 were above the acceptable limit of 10⁻⁶ for all age groups invariably with height and street geometries. The concentration of PMs surpassed the limits prescribed by Indian National Ambient Air Quality Standards in SC (38% of the observations) and SCV (50% of the observations) at different heights. Furthermore, all the observed PMs in three street geometries surpassed the World Health Organization guidelines at all the measured heights. Therefore, it is imperative for regulatory agencies to consider vertical monitoring of air pollutants, in addition to spatial monitoring, since people living at higher altitudes are exposed to different concentrations of pollutants and at various levels of risk.