Analysis of seasonal and spatial patterns of pm2.5 in Sri Lanka using satellite-derived data

Abstract

Sparse ground monitoring and limited reliable evidence for policy hinder air quality management in Sri Lanka. This study employs satellite-derived PM2.5 data from the Global High Air Pollutants (GHAP) product for 2017–2022 using Google Earth Engine and Python, aggregating the data to analyse the temporal dynamics of the pollutant distribution at national and provincial levels. The results show a significant monsoon-driven seasonal cycle—highest concentration in January–March and lowest concentration during the mid-year Southwest monsoon, with a late-year rebound—and persistent spatial disparities, with the Western Province (especially the Colombo urban area) consistently elevated relative to the central highlands. An exploratory weekday analysis for 1 January–31 December 2022 indicates workweek increases that peak mid-to-late week and relax on weekends, underscoring anthropogenic influences. These findings provide a baseline climatology of PM2.5 for Sri Lanka, highlight periods and regions of greatest concern, and motivate targeted weekday traffic/industrial controls in urban hubs.