Urban mobility responses to wildfire smoke-related air quality advisories in Montréal, Canada.

Wildfire smoke events are increasing in frequency and severity, yet evidence on how urban populations modify their mobility in response to air quality advisories remains limited. In this work we apply time-series forecasting modelling to four mobility datasets (bike-share, metro rail, bus, and recreational running). We examine changes to daily activity counts in Montréal, Canada during wildfire smoke-related air quality advisory days from 2022 through 2025. Controlling for seasonality, weather, holidays, and major events, we find that advisories are associated with a shift from active to enclosed transportation modes. Bike-share usage declined while bus and metro ridership significantly increased. Recreational running showed no significant response. Further analysis revealed within-city heterogeneity in these effects. These findings contribute to an emerging literature on urban mobility responses to wildfire smoke and carry implications for public health communication and transportation planning under increasing climate risk.