One of the best reasons to have house plants is to purify the air.  House plants absorb chemicals such as benzene and formaldehydes.   Some the most effect house plants for absorbing pollutants are the Philodendron, Peace Lily, and spider plants.  If you suffer from allergies, consider using Boston Fern or English Ivy.  Studies show that two house plants for an average room will significantly improve the air quality.  Houseplants are great for emotional benefits as well, fostering relaxation, and create a cheerful environment.