Carbon Monoxide Removal by Plants

Dr Bill Wolverton, NASA Research, 1985

Major sources of indoor pollution are tobacco smoke and the combustion of fossil fuels in heaters, gas stoves, water heaters etc. Combustion products are becoming an even greater threat to our health due to increased sealing of homes, offices, and buildings for energy conservation. Reduced ventilation contributes to a build-up of such gaseous combustion products as carbon monoxide (CO).

In 1990 the Plants for Clean Air Council and Wolverton Environmental Services, Inc. began to co-sponsor research that continues to expand upon the earlier NASA research (1989). Houseplants were tested for their ability to remove various toxic gases from sealed test-chambers. All plants that were tested were from local nurseries, kept in their original pots and potting soil, just as they were received from the nursery and were maintained in a greenhouse between tests. All plants were in good health.

Chemical contamination tests were conducted in four Plexiglas chambers:-Two measuring 61cm wide x 61cm deep x 91cm high,and two larger chambers measuring 69cm wide x 69cm deep x 122cm high.

Mounted inside each chamber was a coil of copper tubing through which water (7 degrees Celsius) was circulated. This prevented excessive heat build-up and minimised any fogging from plant respiration in the chambers. The chambers also contained two small removal ports (0.6cm), through which contaminants could be introduced and air samples obtained. A small fan was used to circulate air within each chamber.The test concluded that highly toxic levels of carbon monoxide were reduced to non-toxic levels in 24 hours by one spider plant (Chlorophytum comosum). Therefore, more than 96% of the carbon monoxide was removed.