How Soot-Covered Birds Narrate Pollution's Toxic Legacy

In March 2016, a flock of pigeons took to London’s skies with petite vests strapped to their backs. The tech firm Plume Labs had conscripted the winged denizens as a corps of citizen scientists with a unique vantage point on the city. As the birds swooped around the metro, a sensor in their vests would capture air quality readings. The stunt was an effort to raise awareness about the pollution cloaking the capital—a serious issue all too easy to overlook, the project’s developer told CityLab, because “it’s an invisible, essentially intangible problem.”

In this case, researchers deployed the birds deliberately, as a gimmick to raise awareness and assemble measurements. But across the Atlantic, birds had been collecting air quality data a century earlier, and no one was the wiser.