#4: A Palm Tree.
We're not talking about palm trees at the beach (though a beach vacation is a good way to get away from dirty indoor air). Palm trees used as houseplants are very effective air purifiers, known to remove formaldehyde, which lurks in paints, furniture finishes, and the glues used to hold pressed wood and particle board together. You'll get similar benefits from a variety of other houseplants, but palm trees are among the easiest to care for. Look for Dwarf date, bamboo, areca, lady, or parlor palm varieties.