The Tyre Collective does not yet have a name for its device. Hanson Cheng, one of the London-based startup’s three co-founders, calls it a "box.” Built to attach behind the wheel of a car, truck, van or bus, it’s designed to capture emissions from an often-overlooked source: tires.

Every vehicle sheds tiny bits of its tires as it rolls, but "where the rubber meets the road” is a bit of a misnomer: The tires on most passenger vehicles contain little natural rubber. Instead, they’re made from a stew of petrochemicals, particles of which ultimately wind up in soil, air, waterways and oceans.

The International Union for Conservation of Nature pegs tires as the second leading source of microplastic pollution in oceans, and one 2017 study found a global per capita average of 0.81 kilograms (1.78 lbs) in tire emissions per year, ranging from 0.23 kg per year in India to 4.7 kg (roughly 10 pounds) in the U.S. That may seem minor stacked up against the nearly 300 pounds in plastic waste the average American generates each year, but microplastics are tiny by definition — and an insidious source of toxins that researchers are only beginning to understand.