Uncovering the Air Quality Benefits of Urban Forests Using UAV Surveys

Urban forests play a critical role in air quality regulation in urban areas. This study aimed to utilize unmanned aerial vehicles to monitor the concentrations of NO2, O3 and PM10 at multiple heights during the autumn days in 2022 to evaluate the vertical effects of urban forests on air quality in Shenyang, China. Result showed that NO2 concentrations at 0–1.5 m were 46.99 ± 12.86 µg/m3 in the streets, which was significantly lower than 51.64 ± 7.33 µg/m3 in forests at midday. However, there was no significant difference in O3 and PM10 concentrations at 0–1.5 m between in the forests and in the street. NO2 and O3 concentrations at 1.5–30 m in the forests were significantly lower at that at 1.5–30 m in the street, while PM10 concentrations at 1.5–30 m in the forests were significantly higher at that at 1.5–30 m in the street. The purifying effects of the urban forests on NO2, O3 and PM10 gradually strengthened from midday to afternoon.