Assessment of Urban Air Quality in Dimapur: A Geospatial Analysis of RSPM

Abstract

Air pollution is a major environmental concern in rapidly urbanizing regions, particularly in developing urban centres. Dimapur, the most urbanised district and commercial hub of Nagaland, has experienced increasing deterioration in ambient air quality due to rapid urban expansion, vehicular emissions, construction activities, and commercial growth. This study analyses the spatial distribution and seasonal variation of Respirable Suspended Particulate Matter (RSPM/PM10) across Dimapur during 2023 using Geographical Information System (GIS)-based Inverse Distance Weighted (IDW) interpolation and Exceedance Factor (EF) analysis. The findings reveal that all monitoring locations exceeded the National Ambient Air Quality Standards (NAAQS) annual permissible limit of 60 µg/m³. Dhobinalla recorded the highest annual average RSPM concentration (130 µg/m³), followed by Burma Camp (114 µg/m³), while Viola Colony recorded the lowest concentration (81 µg/m³). Seasonal analysis indicated that winter months experienced the highest pollution levels due to reduced atmospheric dispersion, whereas monsoon months recorded the lowest concentrations because of rainfall-induced pollutant washout. Commercial and traffic-dense areas exhibited significantly higher pollution levels compared to residential and green spaces. The study highlights the urgent need for effective air quality management strategies, including stricter traffic regulation, improved urban planning, expansion of green spaces, and continuous air quality monitoring.