Through the Pedestrian Lens: Revealing Invisible Environmental Burdens in High-Density Urban Areas

Pedestrian exposure to air pollution in dense cities is shaped by where people walk, how long they remain in place, and how pollution varies across streets, yet these dynamics are rarely captured by conventional exposure assessments. This study proposes a pedestrian-oriented framework to characterize street-level PM2.5 exposure by jointly modeling fine-scale pollution variability and pedestrian activity intensity. Using New York City as a case study, high-resolution PM2.5 concentrations are estimated from mobile sensing data, while pedestrian volumes are derived from street-view imagery integrated with station-based counts. The results reveal substantial discrepancies between traditional exposure metrics and pedestrian-specific patterns, demonstrating that critical exposure hotspots arise not only from elevated pollution levels but also from the convergence of moderate pollution and intense pedestrian activity. By reframing air-pollution exposure through pedestrian behavior, this study offers new insights for developing more effective and equitable air-quality interventions in high-density urban environments.