Influence of ozone precursors and particulate matter on the variation of surface ozone at an urban site of Delhi, India

Abstract

Continuous measurements of surface O₃ and its precursors (NO, NO₂, CO, CH₄ and NMHCs) at an urban site of Delhi, India during January 2012 to December 2013 are presented. In the present study, the annual average mixing ratios of surface O₃, NO, NO₂, CO, CH₄ and NMHC were 30 ± 6 ppb, 24 ± 6 ppb, 15 ± 4 ppb, 1.5 ± 0.4 ppm, 2.4 ± 0.4 ppm and 0.4 ± 0.1 ppm, respectively. The maximum average mixing ratios of surface O₃, NO and NO₂ were observed during the summer, whereas, the minimum average mixing ratios of ambient NO and NO₂ were during monsoon seasons. The surface O₃, NO and NO₂ have shown the prominent diurnal variations during all the seasons at the observational site of Delhi. The result reveals that the surface O₃ was negatively correlated with NO_x and CO during the study. The linear scatter plot analysis shows that the PM_2.5 and PM₁₀ present in the ambient air of Delhi influence the production of surface O₃ at observational site.