Investigations on Connections of Ozone with Trace Gases and Meteorological Conditions during the Severe Smog Conditions over Delhi

Abstract

Abstract A tremendous increase in air pollutants has remarkably affected the breathing space in our ecosystem and degraded the air quality. Production of air pollutants integrated with boundary layer meteorology controls the concentration and dilution of contaminants. Air pollution worsens during the wintertime due to smog formation in urban areas. Delhi in India is severely affected by smog in the winter, where surface ozone (O3) and particulate matter are prime contributors. In this work, we have detailedly analyzed the connection between O3 and trace gases, i.e., NOx, carbon monoxide (CO), benzene, toluene, p-xylene, and ammonia, and also the influence of particulate matter and meteorological conditions. Investigations showed a significant negative correlation between O3 and its precursor gases. Particulate matter and ammonia, which may contribute indirectly to ozone formation, seem uncorrelated with ozone. Solar radiation and air temperature contribute positively to ozone formation. Wind-speed positively correlated with ozone, but high wind usually dilutes the concentration of pollutants. Thus positive correlation may represent ozone transport from other locations to observational sites. Toluene and benzene ratio are estimated to understand the nature of emission sources and time duration. The analysis of benzene and toluene fractions at study sites indicates the likely anthropogenic sources of the air masses sampled. Very high T/B values at several sites indicated that benzene was emitted from vehicular emission while toluene was from point sources. Ozone formation potential analysis showed that toluene and p-xylene are the prime contributors to ozone. The site AV showed stringent behavior, which needs further detailed research.