Ozone distributions and urban air quality during summer in Agra – a world heritage site

AbstractUnplanned urban and industrial growth and rise in population are the main factors that had led to air pollution problems. Surface ozone causes human health problems and environmental degradation and acts as a greenhouse gas. Surface ozone is the most significant key substance of photochemical smog. Dependence of air pollutants on meteorology is described with the objective of understanding the prevailing processes pollutants phase interaction. Rigorous measurements of gaseous materials (surface O3, NO2, CO, and SO2) and particulate matter (PM2.5) were carried out regularly during the summer season of 2012 at kerbsite of Agra to assess the characteristics of air pollutants. The air mass trajectories have been calculated using the HYSPLIT 4 and FLEXTRA model. The maximum hourly levels of these pollutants exceeded 116.5 ppb for O3, 96.2 ppb for NO2, 16 ppb for SO2, 4.60ppm for CO and 188µg/m3 for PM2.5. There is obvious diurnal variation in the concentration of surface ozone which clearly follows the diurnal variation of atmospheric temperature. The joint application of principal component analysis and clustering techniques to data collected has led to the recognition of inherent relationships between variables that have been associated with governing processes related to surface O3 formation. The effect of wind on pollutants appears to be noteworthy. We also found that, the maximum average concentrations of SO2 and O3 occurred at humidity ≤30% pinpointing for strong vertical mixing. For CO, NO2 and PM2.5 the maximum average concentrations occurred at humidity below 40%