We drink filtered water, use non-allergenic detergents, and try to refrain from too much candy. But what about the air we breathe? This is what flashed through Ray Wu’s mind as he stepped off a plane in Beijing into a thick shroud of smog.

The air smelled of scorched metal, a brown haze obscurred the landscape, and his throat felt immediately coated with dust. Later on in the trip, the sky turned back to blue—but the sickness continued, and he wasn’t sure why.

He realized that he needed a device that could sense the air and clean it up as needed—wherever he went. In 2014, Ray gathered a team of fellow MIT engineers and renowned designers to create Wynd.