A Comparative Study of Air Quality and Urban Development in Sri Lankan Cities (1980-2024)

Abstract

The aim of this study is to investigate the long -term relationship between urbanization and air quality in four Sri Lankan cities, Colombo, Kandy, Anuradhapura, and Jaffna from 1980 to 2024. As rapid urbanization and economic growth change Sri Lanka's cities through accelerated urbanization, fine particulate matter (PM₂.₅) has emerged as a significant environmental and public health concern. This study employs satellite-derived data from NASA's MERRA-2 and Washington University and ground-based measurements at the U.S. Embassy in Colombo to assess PM₂.₅ and component concentrations, including black carbon (BC), organic carbon (OC), sulfate (SO₄²⁻), dust, and sea salt (SS). Urbanization metrics of population growth, land use change, and household energy consumption were assessed against PM₂.₅ concentrations through time series and comparative analyses. The findings exhibit distinct spatial and temporal pollution trends: while cities like Colombo and Anuradhapura experience stable trends of pollutants, Kandy experiences noticeable increases in PM₂.₅, BC, and SO₄ likely to be influenced by topography and urbanization. Conversely, due to a lack of extensive data availability, population trends in Jaffna were not able to be reasonably evaluated. Seasonal and diurnal analysis also refers to the influence of climatic features like monsoons in defining air quality. This study contributes to the limited body of literature on long-term air quality monitoring in Sri Lanka and makes recommendations for environmental policy and sustainable urban planning. The study also underscores the value of more data collection and integration to guide air quality management in the developing world.