Chapter 17 - Surface ozone in Indian urban region

Abstract

Atmospheric ozone has witnessed a steady increase attributable to anthropogenic activities aligned with the socioeconomic development of cities. Primary pollutants such as particulate matter, carbon monoxide, and nitrogen oxides have been given utmost priority in the air quality assessment studies conducted in the past. Ozone, one of the most important greenhouse gases, has been regarded as a major global concern due to its adverse impacts on the environment, human health, and vegetation. An understanding about the long-term as well as the short-term trends, underlying chemistry and prominent contributing factors for the accumulation of ozone in urban environments, is one of the key aspects that requires due consideration while developing the strategy for restricting its accumulation in the environment. In view of this, the present study aims to enrich the existing literature on ozone accumulation in urban settings by assessing the variability in ozone levels in Delhi city over a period of 10 years between 2008 and 2018 using satellite observations. The analysis in the present study has been restricted to assess the variations in the levels of total columnar ozone (TOC), nitrogen dioxide (NO2), and solar radiation (SR) over Delhi to assess the variations in surface ozone. The results of the analysis revealed that the pollutant has followed an increasing trend over the study region between 2008 and 2018, which is sure to increase in the future. TOC has witnessed an irregular trend over Delhi city between 2008 and 2018 with a significant rise from 2013 to 2015, indicating the need to restrain these levels. Furthermore, numerous studies have highlighted that the increasing levels of surface ozone pose various environmental, human health, and agricultural challenges. Thus, in view of this, the present study provides a preliminary analysis of long-term trends of surface ozone over Delhi city to strategize interventions and actions to restrict the increase in this “new-age pollutant.”