Evaluation and Spatial Mapping of Criteria Air Pollutants in an Industrial City in India

Abstract

Air pollution poses a significant environmental challenge in many urban areas worldwide, largely driven by human activities and increasingly affecting air quality (AQ). This study focuses on mapping various pollutants that are emitted by vehicles using two common spatial interpolation methods: (1) Kriging; and (2) inverse distance weighting (IDW). In the initial phase, spatial interpolation models were developed to highlight the need for sustainable urban development. Air pollutant concentrations were spatially interpolated for seasonal and annual periods at three unmonitored locations [Indra Nagar (IDN), Civil Lines (CVL), and Jajmau (JJM)] in Kanpur City, Uttar Pradesh, India, using data from 2015 to 2020, which was collected from eight monitoring stations. A vulnerability analysis was performed for the study period and visualized spatially. The results showed a steady annual rise in the total vulnerable score (VST) from 2016 to 2020, which reflects increasing vehicular emissions. The predicted VST values indicated that the most significant deterioration in AQ occurred in the industrial area of JJM, and the residential area of IDN saw the least impact. Seasonally, the IDW provided more accurate VST predictions for residential and commercial areas during summer. Kriging performed better in the monsoon and winter months due to more complex spatial patterns. A similar trend was observed in the industrial area, with the IDW being effective postmonsoon and Kriging excelling during the monsoon and winter. Analyzing specific pollutants such as particulate matter (PM) (e.g., PM10), sulfur dioxide (SO2), and nitrogen dioxide (NO2), this study identified significant underpredictions and overpredictions at various sites. In addition, the findings could help to estimate pollutant levels at unmonitored locations, which could offer deeper insights into spatial patterns and AQ trends in Kanpur. This study underscores the importance of enhancing AQ monitoring and controlling vehicular emissions to mitigate the development of air pollution hot spots in the city.