Promoting sustainable travel decisions through health and active lifestyle messaging

U.S. travelers heavily rely on personal vehicles for daily travel, contributing to an estimated $260 billion annually in social costs from tailpipe emissions. Most people seldom realize how much air pollution they are exposed to during their daily travel or how switching modes could benefit their health. Here we examine whether messages about health and active lifestyle benefits delivered through mobile apps can encourage travelers to walk, bike, or take the bus, overcoming present bias. Using randomized A/B testing in a nationally representative sample of 4,840 U.S. car owners, we test whether mobile app-based messages about the health and active lifestyle impacts of their daily travel decisions can shift preferences towards sustainable modes. We find that travelers are more likely to choose sustainable modes over personal vehicles when provided with credible, health-focused messages at the time of decision-making. These strategies were particularly effective for urban residents and individuals with pre-existing health conditions, but they backfired for long-distance commuters, underscoring a key tension between travel time and perceived health risks. When paired with existing mobility apps, such behavioral interventions can potentially reduce 1 billion car miles at a cost of 2-4 cents per trip, offering a complementary alternative to existing approaches such as reduced fares, free fares, or direct cash.