To learn more about air pollution in cities, researchers at the Lawrence Berkeley National Laboratory traveled to New Dehli, India to measure the air quality during rush hour traffic. Lead author Josh Apte says that this approach has cleared a lot of ambiguities about the types and levels of pollutants that people are exposed to.

"One of the things we were looking at in particular is how the levels of air pollution compare in traffic to what you see at the official air pollution monitoring sites, which typically are not in traffic and instead on the roofs of buildings where they can sort of tell you more about what the background levels of air pollution are in a city. And what we found is the levels of air pollution were substantially higher in traffic than in urban background levels."

One of the goals of the study is to connect patterns of air pollution in New Dehli to our own cities in the U.S.

"So things that we’ve learned about how levels of air pollution are elevated in traffic in India actually give us useful insights about how the behavior of pollutants occurs in American cities."