Photosynthesis is the process that causes plants to absorb carbon dioxide and exude oxygen. This makes them a good addition to office buildings and private homes for the sake of atmospheric refreshment. The National Aeronautics and Space Administration (NASA), in association with the Associated Landscape Contractors of America (ALCA), tested various methods that could potentially assist in cleaning the breathable atmosphere of yet-to-be-built space stations. Since these structures would be sealed against oxygen loss, air treatments would have to take place from within. The agency discovered that 15 to 18 larger houseplant specimens and blooming potted plants (in containers measuring 6 to 8 inches in diameter) can remove considerable levels of undesirable gases. Sometimes the amounts were as high as 87 percent in a 24-hour period from the equivalent of a 1,800-square-foot home.
NASA tests reveal that the best plants for absorbing atmospheric benzene are English ivy (Hedera helix), the peace lily (Spathiphyllum 'Mauna Loa'), the Madagascar dragon tree (Dracaena marginata), its cultivars Janet Craig (Dracaena deremensis 'Janet Craig') and Warneckii (Dracaena deremensis 'Warneckii'), the gerbera daisy (Gerbera jamesonii) and the florist's chrysanthemum (Chrysantheium morifolium). Tobacco smoke, gasoline, dyes and synthetic fibers, as well as plastics and paints, emit benzene.
Trichloroethylene is a chemical you may find in varnish, adhesives, some paints and lacquers but also in a commercial dry-cleaning environment. The best plants for cleaning breathable air containing this gas are the peace lily (Spathiphyllum 'Mauna Loa'), Warneck dracaena (Dracaena deremensis 'Warneckii'), gerbera daisy (Gerbera jamesonii) and florist's chrysanthemum (Chrysantheium morifolium).
Fire retardant chemicals frequently contain formaldehyde. It is also a byproduct of cigarette smoke and adhesives application. Foam insulation and treated pressed-wood furniture may also emit formaldehyde. The best plants for cleaning the air when it contains this gas are English ivy (Hedera helix), the spider plant (Chlorophytum comosum), devil's ivy (Epipremnum aureum), the peace lily (Spathiphyllum 'Mauna Loa'), the bamboo palm (Chamaedorea sefritzii), snake plant (Sansevieria trifasciata 'Laurentii') and heartleaf philodendron (Philodendron cordatum). Other formaldehyde removing plants include the selloum philodendron (Philodendron selloum), elephant ear (Philodendron domesticum), red-edged dracaena (Dracaena marginata), cornstalk dracaena (Dracaena fragans 'Massangeana') and also the florist's chrysanthemum (Chrysantheium morifolium).
Basic respiration produces carbon dioxide. Plants---when not photosynthesizing---breathe in oxygen and emit carbon dioxide. This gas is also a by-product of fossil fuel combustion. Use orchids, succulents and epiphytic bromeliads to continue the exchange of oxygen and carbon dioxide at night, when most other plants do not photosynthesize.