Did air pollution continue to affect bike share usage in Seoul during the COVID-19 pandemic?

INTRODUCTION: The role of cycling has become more important in the urban transport system during the Covid-19 pandemic. As public transport passengers have tried to avoid crowded vehicles due to safety concerns, a rapid surge of cycling activities has been noted in many countries. This implies that more cyclists might be exposed to air pollution, potentially leading to health problems in cities like Seoul where the level of air pollution is high. METHODS: We utilised three years of bike sharing programme (Ddareungi) data in Seoul and time series models to examine the changes in the relationship between particulate concentration (PM(2.5)) and total daily cycling duration before and during the pandemic. RESULTS: We find that cyclists reacted less to the PM(2.5) level during the pandemic, potentially due to the lack of covid-secure travel modes. Specifically, our results show significant negative associations between concentrations of PM(2.5) and total daily cycling duration before the pandemic (year 2018 and 2019). However, this association became insignificant in 2020. CONCLUSIONS: Building comprehensive cycling infrastructure that can reduce air pollution exposure of cyclists and improving air quality alert systems could help build a more resilient city for the future.