Differentiating local and regional drivers of exceedances of WHO PM2.5 standards with a low-cost sensor network in the greater male’ region (GMR)

Although pollution is visible at certain times in the capital Greater Male’ Region (GMR), Maldives, only limited quantitative measures of the pollution concentrations are available. Hence, this study aims to understand the spatiotemporal patterns of Particulate Matter 2.5 (PM2.5) and its contribution by both local and regional sources. Data was collected using harmonized and calibrated low-cost PM sensors from October 2021 to September 2023 across 8 locations in GMR. Results showed that the annual average PM2.5 concentration in both years surpassed the WHO guideline. Higher levels of PM2.5 were measured in the dry season and the 24-h WHO-recommended level was surpassed in 67% of the days in the dry season. This is the effect of pollutants transported from the subcontinental regions. PM2.5 concentrations in at least 93% of the days in the wet season (Apr–Oct) remained within the daily limit. Similar levels and patterns of PM2.5 concentrations were noticed across all locations, despite higher concentrations and more frequent exceedances were observed in certain locations in GMR. Besides vehicular emission, electricity generation, biomass burning, sea transport and construction activities are the likely local sources of PM2.5. The diurnal trend revealed significant peaks on weekend evenings in some hotspots due to increased outdoor activities. Hence to reduce regional drivers of pollutants, corporations from countries in the region must take action and municipalities need to implement plans to moderate local emissions.

Duke Scholars

Author Michael Howard Bergin Civil and Environmental Engineering