Project Summary
Traffic-related air pollution and commuting stress are established health concerns. For cyclists, exercise reduces physiological stress and increases exposure to pollution, while traffic interactions can dramatically increase stress. This study evaluates whether protected cycle lanes changes this exposure profile. The research team proposes to assess air quality and stress in cyclists and motorists before and after construction of a 7-km protected bike lane on Ohio and Westwood Avenues in west Los Angeles. Participants will carry ultrafine particle (UFP; particles smaller than 0.1 µm) counters with GPS. Black carbon will additionally be measured on a subset of commutes. UFP is a sensitive tracer of vehicle emissions; it has a low urban background, sharp roadside gradients, and is reliably measured at 1-second time resolution. Physiological stress will be measured via heart-rate-variability wearables, and perceived stress will be assessed with validated questionnaires. Roadside cameras with AI-assisted analysis will characterize traffic flow. While a few studies (mostly in Europe) have investigated the impact of road infrastructure on pollutant exposures for cyclists, this research focus on stress outcomes is novel. The research team hypothesizes that protected infrastructure lowers cyclist stress and pollutant exposures. Further, this research will explore effects on motorists and aim to generate evidence to inform transit policy.
