Subways and Urban Air Pollution
Matthew A. Turner
- American Economic Journal: Applied Economics (Forthcoming)
We investigate the effect of subway system openings on urban air pollution. On average,
particulate concentrations are unchanged by subway openings. For cities with higher initial
pollution levels, subway openings reduce particulates by 4% in the area surrounding a city center.
The effect decays with distance to city center and persists over the longest time horizon that we can
measure with our data, about four years. For highly polluted cities, we estimate that a new subway
system provides an external mortality benefit of about $1b per year. For less polluted cities, the
effect is indistinguishable from zero. Back of the envelope cost estimates suggest that reduced
mortality due to lower air pollution offsets a substantial share of the construction costs of subways.
Forthcoming Article Downloads