City pavement is a big source of air pollution
Asphalt in cities heats up during the day. (Aleksandar Langer/Unsplash/)Witnessing a hazy summertime sky in Los Angeles, you might be tempted to blame the cars and trucks that teem on the region’s roadways. And that’s mostly right, but an increasing share of air pollution is coming from the stuff below those vehicles: asphalt.A new study published yesterday in Science Advances finds that asphalt pavement and roofing give off lots of gases that go on to form air pollutants. In summertime, asphalt in cities might contribute more to pollutants called secondary organic aerosols than cars and trucks.A large chunk of the fine particulate matter pollution in urban areas—ranging from 20 to 70 percent—is secondary organic aerosols, or SOAs. Though air pollution vastly improved in recent decades—thanks largely to technology and policy aimed at motor vehicles—it remains a problem in many large cities. Parts of Southern California, for example, still can’t meet...