Measuring exposure to pollution
What’s the best way to measure human exposure to urban pollution? Typically, cities do so by studying air-quality levels in fixed places. New York City, for example, has an extensive monitoring network that measures air quality in 155 locations. But now a study led by MIT researchers, focused on New York City, suggests that using mobile-phone data to track people’s movement provides an even deeper picture of exposure to pollution in urban settings. The study, based on data from 2013, broke New York City into 71 districts and found that in 68 of them, exposure levels to particulate matter (PM) were significantly different when the daily movement of 8.5 million people was accounted for. Specifically, the flow of people into parts of midtown Manhattan, and some parts of Brooklyn and Queens close to Manhattan, appeared to increase aggregate exposure to PM in those areas. Meanwhile, the daytime movement of people away from Staten...