Boston ferns remove more formaldehyde than any other plant. They are also highly efficient at removing other indoor air pollutants, such as benzene and xylene.
Care: The downside is that they can be finicky. You need to feed them weekly in seasons when they are growing, monthly during the winter, and they like to be watered regularly. Depending on the humidity and moisture levels in your home, you may need to water them or mist their leaves daily.