This project is a study of the effects of subways on urban air pollution, examining the 161 subway systems in the world in 2013 and the measures of air pollution calculated from remote sensing data. The investigation will provide an understanding of the effect of subways on cities, which is important for policy makers interested in the process of urbanization in the developing world, for examining proposals to build or extend subway systems, and for evaluating the cost-benefit analysis of subway construction.

Over the coming decades, an enormous migration of rural population towards major urban areas is expected, which will come with large demands for urban infrastructure. In order to assess trade-offs between different types of infrastructure in these cities, it is vital to understand the implications of different types of infrastructure for urban growth and pollution.