Urban cyclists’ exposure to PM2.5: A quantitative analysis using trajectory data and mobile monitoring

Abstract

Cyclists are particularly vulnerable to exposure to air pollutants, such as PM_2.5; however, few studies have systematically incorporated bicycle usage patterns into the assessment of cyclists' PM_2.5 exposure. This study introduces a novel framework that integrates shared bicycle trajectory data with mobile monitoring to quantitatively assess cyclists' PM_2.5 exposure. To evaluate the effectiveness of the proposed methodology, a pilot study was conducted in Shenzhen, China. The results show that 60.45 % of cycling distances are less than 2 km, demonstrating its effectiveness in addressing urban short-distance travel issues. Cycling activity peaks during the morning and evening rush hours, with major hotspots including the Shenzhen-Hong Kong border area, the southwest of Longhua District, the southern part of Baoan District, and the central part of Nanshan District. The PM_2.5 monitoring results show that the majority of the monitored routes recorded average PM_2.5 concentrations exceeding 15 μg/m³ during the monitored periods, which is the World Health Organization guideline. The average PM_2.5 inhalation dose for cyclists on weekdays is 7.49 μg/km, slightly higher than the 7.27 μg/km observed at weekends. Our results indicate that cyclists face increased health risks, such as respiratory diseases, due to prolonged exposure to elevated PM_2.5 levels. These findings can help city managers develop policies to improve the cycling environment for riders and promote low-carbon transportation.