Nationwide assessment of ambient fine particulate matter using lowcost sensors: practicality and feasibility
Urban air quality in the Maldives remains understudied, partly due to a lack of capacity to establish reference air quality monitoring stations. This study assessed the practicality and feasibility of measuring fine particulate matter, PM2.5, using low-cost sensors (LCS), BlueSky 8134, across 8 locations in the Greater Male' Region and 9 locations in the other atolls. Sensors were colocated to harmonize the measurements before deployment. Linear regression for the harmonization revealed high inter-unit reliability, R2 ranging from 0.952 to 0.999. Calibration against a reference station in the neighbouring country, with similar climate conditions, resulted in a moderate to strong correlation (R2 of 0.685). Harmonisation and calibration data were used to correct a yearlong dataset from the sensor network. An average of 87% of valid hourly data was obtained. Across the Maldives, the annual average concentration in all the islands exceeded the WHO standard. The highest annual average (17.9 µg/m3) was observed in the northernmost island, while the lowest(11.1 µg/m3) was measured in the southernmost island. PM2.5 concentrations gradually decrease from north to south, indicating the impact of transboundary pollution. Seasonal impacts are evident across all the sites. Operational challenges faced included accessibility to sites due to the geographical constraints, power outages, and wifi connectivity issues. Despite the challenges, continuously assessing PM2.5 across the Maldives was achieved using the lowcost sensor network. This study proved the potential of LCS in providing extensive and real-time data to better assess air quality for effective air quality management.
