Health impacts of bus rapid transit systems in seven cities worldwide.

Bus rapid transit (BRT) systems serve over 34 million daily passengers in 180 cities worldwide, yet their population health impacts have not been quantified across cities using standardized methods. We estimated mortality impacts and economic value of BRT in seven cities across four continents (Bogota, Brisbane, Helsinki, Istanbul, Mexico City, Miami, Paris) using comparative risk assessment with probabilistic uncertainty analysis. We assessed all-cause mortality changes from three pathways (physical activity, PM2.5 inhalation, traffic crashes) applying the WHO HRAPIE-2 endorsed Orellano et al. (2024) PM2.5 dose-response function. Four car-to-BRT substitution scenarios were evaluated using Monte Carlo simulation (10,000 Latin Hypercube iterations per scenario, six sampled parameters). Economic impacts used country-specific values of a statistical life. Under the current observed substitution, BRT prevented a median of 160 deaths per year (95% UI: -30 to 374), valued at USD 176 million (95% UI: 36 to 477 million). Under complete substitution, 1795 deaths were prevented (95% UI: 432 to 4355) valued at USD 1665 million. Per-city rates ranged from 0.02 to 0.75 deaths prevented per 100,000 metropolitan residents per year under current substitution. Physical activity gains drove the majority of net benefits, partially offset by increased PM2.5 inhalation during walking. Bogota and Mexico City contributed about 80% of total deaths prevented. Cities investing in BRT should pair infrastructure with measures that maximize car-to-BRT substitution and reduce in-corridor PM2.5 exposure, the two levers that determine whether modal shift translates into population-level mortality reduction.