Impact of bicycle infrastructure and long-term exposure to PM_2.5 on cycling

Cycling behavior is affected by various factors, including infrastructural and environmental factors. While bike infrastructure and air quality may have effects on cycling, their joint impacts were less known. The present study examined yearly changes in public bike-sharing (PBS) usage across 423 neighborhoods in Seoul, South Korea between 2018 and 2021. We quantified how concurrent changes in the number of PBS rental stations and ambient PM_2.5 concentration levels influenced PBS usage patterns using a statistical method, namely, a variant of difference-in-difference method. The results showed that the relative rates of changes in the PBS usage (i.e., rental frequencies) for 1 μg/m³ increase of PM_2.5 and one bike station expansion are −0.168 (95 % CI; −0.188, −0.149) and 0.024 (95 % CI; 0.019, 0.029), respectively. We also found that adult cyclists aged over 50 years old are more sensitive to poor air quality than younger age groups. Our analysis suggests that improvements of PBS infrastructure and cleaner air quality are both positively associated with increased PBS usage.