We all know that having houseplants indoors can help filter out toxins and purify the air in your home. But not all plants are the same when it comes to freshening the air. The master of air purification award goes to the Boston fern, which tops the list of most effective in purification. And they are pretty easy to maintain and keep alive: Just place the fern by a window for lots of sun and water every few days. Move the plant from room to room regularly to purify the air all over your house.