Assessing atmospheric particulate matters and their removal potential through roadside trees in Chattogram city, Bangladesh

Abstract

Atmospheric particulate matter (PM) affects urban air quality and poses significant health risks. In this study, we measured ambient PM levels and heavy metal concentrations at six vegetated and one non-vegetated (control) roadside locations in Chattogram City, Bangladesh. Using a portable air quality sensor, we assessed ambient PM_0.5 and PM_2.5 concentrations every 15 days over the course of one year and found that the mean concentrations of PM₀.₅ and PM₂.₅ in the control site were significantly higher (p ≤ 0.05) than those at the vegetated roadsides. We also investigated whether roadside trees can effectively remove PM and collected 84 leaf samples from seven tree species each month to quantify PM deposition on the leaves. PM concentrations in the air and on the leaves were higher during the dry season compared to the rainy season. Further analysis of meteorological factors revealed that PM accumulation on the leaves decreased with high temperature, wind speed, and precipitation. These findings suggest that meteorological conditions play a crucial role in PM dynamics, influencing both airborne concentration and accumulation on leaves. Besides, tree species and leaf characteristics play a substantial role in PM accumulation on the leaves. Copper and zinc were in the accumulated PM along all roadsides, indicating the possibility of heavy metal contamination. We propose planting roadside trees with rhomboid, elliptical, rough, and simple leaves to enhance the removal of PM and other contaminants through deposition.