NASA Clean Air Study
The NASA Clean Air Study has been led by the National Aeronautics and Space Administration (NASA) in association with the Associated Landscape Contractors of America (ALCA). Its results suggest that certain common indoor plants may provide a natural way of removing toxic agents such as benzene, formaldehyde and trichloroethylene from the air, helping neutralize the effects of sick building syndrome.
The study was the only one ever done with NASA involvement and NASA has not used plants to clean air in the space station. The quantitative pollutant removal rate reported by the NASA research is equivalent to 1/10 of an air change per hour, the ventilation rate due to air leakage in a very tightly sealed house filled with three layers of plants, leaving no room for furniture or people. In fact, the practicality of using plants to clean indoor air has not been demonstrated.
The first list of air-filtering plants was compiled by NASA as part of a clean air study published in 1989. which researched ways to clean air in space stations. As well as absorbing carbon dioxide and releasing oxygen, as all plants do, these plants also eliminate significant amounts of benzene, formaldehyde and trichloroethylene. The second and third list are from B. C. Wolverton's book and paper and focus on removal of specific chemicals.
NASA researchers suggest efficient air cleaning is accomplished with at least one plant per 100 square feet of home or office space. Other research has shown that micro-organisms in the potting mix (soil) of a potted plant remove benzene from the air, and that some plant species also contribute to removing benzene.
Chart of air-filtering plants
|Plant, removes:||benzene||formaldehyde||trichloroethylene||xylene and toluene||ammonia|
|Dwarf date palm (Phoenix roebelenii)||no||Yes||no||Yes||no|
|Areca palm (Dypsis lutescens)||no||no||no||Yes||no|
|Boston fern (Nephrolepis exaltata 'Bostoniensis')||no||Yes||no||Yes||no|
|Kimberly queen fern (Nephrolepis obliterata)||no||Yes||no||Yes||no|
|English ivy (Hedera helix)||Yes||Yes||Yes||Yes||no|
|Lilyturf (Liriope spicata)||no||Yes||no||Yes||Yes|
|Spider plant (Chlorophytum comosum)||no||Yes||no||Yes||no|
|Devil's ivy, Money plant (Epipremnum aureum)||Yes||Yes||no||Yes||no|
|Peace lily (Spathiphyllum 'Mauna Loa')||Yes||Yes||Yes||Yes||Yes|
|Flamingo lily (Anthurium andraeanum)||no||Yes||no||Yes||Yes|
|Chinese evergreen (Aglaonema modestum)||Yes||Yes||no||no||no|
|Bamboo palm (Chamaedorea seifrizii)||no||Yes||no||Yes||no|
|Broadleaf lady palm (Rhapis excelsa)||no||Yes||no||Yes||Yes|
|Variegated snake plant, mother-in-law's tongue (Sansevieria trifasciata 'Laurentii')||Yes||Yes||Yes||Yes||no|
|Heartleaf philodendron (Philodendron cordatum)||no||Yes||no||no||no|
|Elephant ear philodendron (Philodendron domesticum)||no||Yes||no||no||no|
|Red-edged dracaena (Dracaena marginata)||Yes||Yes||Yes||Yes||no|
|Cornstalk dracaena (Dracaena fragrans 'Massangeana')||Yes||Yes||Yes||no||no|
|Weeping fig (Ficus benjamina)||no||Yes||no||Yes||no|
|Barberton daisy (Gerbera jamesonii)||Yes||Yes||Yes||no||no|
|Florist's chrysanthemum (Chrysanthemum morifolium)||Yes||Yes||Yes||Yes||Yes|
|Rubber plant (Ficus elastica)||no||Yes||no||no||no|
|Dendrobium orchids (Dendrobium spp.)||no||no||no||Yes||no|
|Dumb canes (Dieffenbachia spp.)||no||no||no||Yes||no|
|King of hearts (Homalomena wallisii)||no||no||no||Yes||no|
|Moth orchids (Phalaenopsis spp.)||no||no||no||Yes||no|
Most of the plants on the list evolved in tropical or subtropical environments. Due to their ability to flourish on reduced sunlight, their leaf composition allows them to photosynthesize well in household light.
- Eichhornia crassipes
- Green wall
- Rain garden
- Dracaena reflexa
- Indoor air quality
- BC Wolverton, WL Douglas, K Bounds (July 1989). A study of interior landscape plants for indoor air pollution abatement (Report). NASA. NASA-TM-108061.
- Pottorff, L. Plants "Clean" Air Inside Our Homes. Colorado State University & Denver County Extension Master Gardener. 2010.
- Wolverton, B. C., et al. (1984). Foliage plants for removing indoor air pollutants from energy-efficient homes. Economic Botany 38(2), 224-28.
- Wolverton, B. C., et al. A study of interior landscape plants for indoor air pollution abatement: an interim report. NASA. July, 1989.
- Wolverton, B. C. (1996) How to Grow Fresh Air. New York: Penguin Books.
- Wolverton, B. C. and J. D. Wolverton. (1993). Plants and soil microorganisms: removal of formaldehyde, xylene, and ammonia from the indoor environment. Journal of the Mississippi Academy of Sciences 38(2), 11-15.
- Orwell, R.; Wood, R.; Tarran, J.; Torpy, F.; Burchett, M. (2004). "Removal of Benzene by the Indoor Plant/Substrate Microcosm and Implications for Air Quality". Water, Air, and Soil Pollution 157 (1-4): 193–207. doi:10.1023/B:WATE.0000038896.55713.5b.
- Wolverton, B. C., et al. Interior landscape plants for indoor air pollution abatement: final report. NASA. September, 1989. pp 11-12.
- American Society for Horticultural Science. Indoor plants can reduce formaldehyde levels. ScienceDaily. February 20, 2009. Quote: "...Complete plants removed approximately 80% of the formaldehyde within 4 hours. Control chambers pumped with the same amount of formaldehyde, but not containing any plant parts, decreased by 7.3% during the day and 6.9% overnight within 5 hours..." In reference to: Kim, J. K., et al. (2008). Efficiency of volatile formaldehyde removal by indoor plants: contribution of aerial plant parts versus the root zone. Horticultural Science 133: 479-627.