Navigating haze: Assessing the effect of transboundary haze on households’ choice of transportation mode during the school run

Singapore is affected by transboundary haze events, where adverse health effects from particulate pollutants exposure instigate individuals to take protective measures. Transport policymakers are concerned how individuals might change their commuting behaviours to reduce outdoor air exposure— specifically, switching from “open” transport modes (walking, etc.) where commuters may be required to wait for transit or travel the last mile outdoors, to “closed” transport modes (point-to-point private transport). Such trends make efforts to reduce reliance on private transport more challenging. We assess the effect that knowledge of an impending haze event has on parents' transport mode decisions for their primary school child's school commute. We exploit a randomized experiment embedded within a survey to tease out the incremental effect of varying transboundary haze severity (Band 2: Elevated, Band 3: High, Band 4: Very High) on parents' preference to send their child to school via “closed” transport modes. We find that while haze increases parents' motivation to switch to “closed” modes of transportation, the effect is not linear. Our findings have implications for transport mode utilization beyond haze to all aspects of environmental harms, as households grow increasingly aware and concerned about the interaction of transportation and health outcomes.