Why?
Houseplants can help remove certain harmful volatile organic chemicals (VOCs) from indoor air. Things nobody wants around their lungs, or their kids.

What are VOC's? (From the EPA) Volatile organic compounds (VOCs) are emitted as gases from certain solids or liquids. VOCs include a variety of chemicals, some of which may have short- and long-term adverse health effects. Concentrations of many VOCs are consistently higher indoors (up to ten times higher) than outdoors.  VOCs are emitted by a wide array of products numbering in the thousands. Examples include: paints and lacquers, paint strippers, cleaning supplies, pesticides, building materials and furnishings, office equipment such as copiers and printers, correction fluids and carbonless copy paper, graphics and craft materials.

EPA's Total Exposure Assessment Methodology (TEAM) studies found levels of about a dozen common organic pollutants to be 2 to 5 times higher inside homes than outside, regardless of whether the homes were located in rural or highly industrial areas. Additional TEAM studies indicate that while people are using products containing organic chemicals, they can expose themselves and others to very high pollutant levels, and elevated concentrations can persist in the air long after the activity is completed.

What plants?

• palms
• ferns
• corn plant
• dragon tree (dracaena)
• rubber plant
• weeping fig (ficus)
• English ivy
• peace lily
• florist mum
• gerber daisy
• dumb cane (dieffenbachia)
• schefflera
• orchid
• spider plant
• philodendron
• arrowhead plant
• pothos
• dwarf banana and
• Chinese evergreen.

In the late 1980s, NASA and the Associated Landscape Contractors of America (ALCA) conducted a study of 19 houseplants in an attempt to find ways to purify air for extended stays in orbiting space stations. The tests were conducted in sealed test chambers that contained pollutants such as formaldehyde, benzene and trichloroethylene, commonly present in indoor air from paints, varnishes, insulation, particleboard, pressed wood, adhesives and other sources.

What they learned for outer space can be applied to your inner space as well. Many of these plants are adapted to tropical climates and grow under dense canopies and low-light conditions. They have to be superefficient in capturing light as well as in processing the gases necessary for photosynthesis. Because of these traits, they have greater potential for capturing other gases, including harmful ones.