The Delhi Metro (DM) is an electric based mass rapid transit system serving the National Capital Region of India. It is also the world’s first rail project to earn carbon credits under the Clean Development Mechanism of the United Nations Framework Convention on Climate Change for reductions in energy consumption and CO2 emissions. In this paper we analyze whether the DM led to reductions in localized pollution measured in terms of NO2; CO; and PM2:5; three transportation source pollutants present at dangerously high levels in Delhi. We study the period between 2004 and 2006, and find that one of the larger rail extensions of the DM led to a 34 percent reduction in localized CO at a major traffic intersection in the city. Our study highlights an important social benefit of the metro rail, but it does not advocate the thoughtless building of capital intensive metro rail projects without first undertaking a thorough cost benefit analysis.
