The best place to put your air purifier is in the room where you spend the most time. But you should also consider the size of the room and the type of air purifier that you have. If you have a small room, like a bedroom, you can put the air purifier on a nightstand or dresser. If you have a larger room, like a living room, you can put the air purifier on the floor. And if you have an industrial-sized air purifier, you may need to mount it on the wall or ceiling.