Every day we are exposed to indoor pollutants. Ordinary consumer products used in a home, such as air fresheners, cleaning compounds, household pesticides and even building materials and furnishings, may be more of a threat to our health than industrial pollution.
Houseplants are often thought to reduce contaminants in the air and improve indoor air quality. In 1989, NASA did a study on whether plants could be used to clean air in space stations. Researchers grew 17 kinds of houseplants in small sealed chambers and found they absorbed benzene, formaldehyde and trichloroethylene – three of the worst pollutants in indoor environments. These compounds can often be found in synthetic carpeting, fabrics, laminates, plastic-coated wallpaper and other substances that “off-gas” chemical compounds.
However, the U.S. Environmental Protection Agency (EPA) claims that the small chamber growing results collected in the NASA experiment may not translate well to real world environments. The EPA writes, “The only available study of the use of plants to control indoor air pollutants in an actual building could not determine any benefit from the use of plants. As a practical means of pollution control, the plant removal mechanisms appear to be inconsequential compared to common ventilation and air exchange rates. In other words, the ability of plants to actually improve indoor air quality is limited in comparison with provision of adequate ventilation.”
The Practical Asthma Review examined both NASA’s research and EPA claims. They strongly support the idea that additional research needs to be conducted in real world situations to determine if plants can clean the air and how many it would take to treat an average home effectively. Plants do convert carbon dioxide in the air into oxygen. How well a plant may clean air depends on what type of plant it is, the concentration of the pollutant, the amount of air circulation and the size of the air space to be cleaned, among other factors. They also point out that while using plants may have benefits, there may also be drawbacks, such as raised humidity (possibly a good thing in Nevada), microbial development and possible degradation products resulting from the plants creating their own chemical pollutants. It may even be possible that large numbers of plants may actually produce and add semi-volatile compounds to the air to protect themselves from insects and for other purposes (http://www.practicalasthma.net/pages/topics/aaplants.htm). Whether or not plants clean the air is a complex problem without a simple answer.
While scientists discuss more research on plants and air quality, I’m still promoting keeping plants in the home, if only to make it more attractive.