The idea is simple enough: Plants naturally filter toxins. So the design has a fan that silently sucks up air, and forces that air over a houseplant's leaves and soils. Pollution-free air then circulates through the room.
The designer, Mathieu Lehanneur, won a rack of awards for the concept. But he then went gone on to test it in labs, and claims that it's 40 times more efficient than HEPA or activated carbon filters. (For real?!) He also claims that instead of shunting noxious pollutants onto a filter, the plant itself metabolizes the waste and eliminates pollution. The added bonus: There are no filters to change.
You can use any houseplant with the filter, but the best performing ones are Peace Lily, Red-edged Dragon tree, Spider Plant, and Aloe Vera. So why not just get one of those plants and let them clean the air on their own? Because the fan, by sucking up more air at greater volumes, cleans things up faster than plants could on their own.