Vertical distribution analysis of PM2.5 concentration at urban highway intersections using low-cost sensors and unmanned aerial vehicles

The high level of particulate matter (PM) is a critical issue in megacities and a major environmental challenge in urban management. Currently, the vertical distribution of PM concentration has been overlooked at traffic hot spots in the design and construction of high-rise buildings. This study assessed the vertical profile of PM2.5 concentration using low-cost sensors and drones to find the residents' exposure to PM2.5 at high-rise buildings. The results showed that the vertical pattern of the PM2.5 concentration on highways with lower traffic of light-duty vehicles (LDVs) was affected by height, with a 30 % increase in PM2.5 concentration at 15 m above the ground compared to ground-level concentration. In contrast, the concentration of PM2.5 on highways with more Heavy-Duty Vehicles (HDVs) traffic at ground levels was about 20 % higher than that at 15 m, gradually decreasing to 23 % at 30 m. The results revealed that PM2.5 concentration could increase with height in high-rise buildings near highway intersections instead of dilution, which would adversely affect the health of the residents. The findings of this study can be considered by urban planners and decision-makers to reduce PM2.5 exposure before settling the citizens in high-rise buildings.