Despite technological advances to reduce energy and materials use and growing political will to pursue green development, population growth in cities is putting ever-greater pressure on the pursuit of sustainability in urban areas. As cities grapple with ongoing environmental challenges, they also face interactions between environmental pollution and public health risks. A notable example is local air pollution, which has been associated with greater susceptibility to respiratory infections. Growing populations increase the exposure to particulate matter in urban areas, and rising incomes increase the total amount of emissions produced as more people are able to own vehicles.