The space program has led the way to a fascinating and important discovery about the role of houseplants indoors. NASA has been researching methods of cleansing the atmosphere in future space stations. This is done to keep them fit for human habitation over extended periods of time. What researchers have discovered is that many common houseplants and blooming potted plants help fight pollution indoors. These plants are reportedly able to scrub significant amounts of harmful gases out of the air, through the everyday processes of photosynthesis. In addition some pollutants are also absorbed and rendered harmless in the soil.
Plant physiologists have already known that plants absorb carbon dioxide and release oxygen as part of the photosynthetic process. Now these researchers have found many common houseplants absorb benzene, formaldehyde and trichloroethylene, as well. Many researchers feel that all houseplants are beneficial in this regard, at least to a certain degree, though they have not all been tested. Of the plants that have been tested, not all have proven equally efficient cleaners. In addition we can not assume all harmful pollutants can be removed in this manner.
It is important to keep in mind that some houseplants are better at removing formaldehyde from the air, while others do a better job on benzene; yet none is much help when it comes to tobacco smoke. But the testing results show that there is sufficient data that known plants can do a good enough job of removing pollutants from the air we breathe to cause us to view houseplants as more than just an attractive feature in decorating the interior environment.
Formaldehyde, benzene and tobacco smoke are three of the worst offenders found in relatively new homes and offices. This is due in part to the fact that newer buildings are constructed largely with man-made building materials and furnished with synthetic carpeting, fabrics, laminated counters, plastic coated wallpaper, and other materials known to “off-gas” pollutants into the interior environment. In addition the advent of the “energy crisis” a number of years back has increased the problems associated with indoor pollutants. Newly constructed buildings are being built better insulated and are sealed tightly to conserve heat or air-conditioning. While this does save both money and energy, this new found efficiency has its downside in that pollutants may be trapped indoors and has less opportunity to dissipate to the outside. The phrase coined to describe this unfortunate result has been called “sick building syndrome.”
If your home is old enough to be leaky and drafty, you may not need to worry about having the “sick-building syndrome.” But if you live in a newer, energy-efficient home with windows and doors that are tightly sealed, or you work in a building where the air feels stale and circulation seems poor, the liberal use of houseplants can be an easy way to help make a dent in the problem.
NASA scientists have studied nineteen different plant species for two years. Of the specimens that have been studied, only two were primarily flowering plants (chrysanthemums and gerbera daisies). Most of the plants that were tested are “true” houseplants, kept indoors year-round though they may be placed outdoors during warm summer months. One is the common succulent, Aloe Vera, also known as “medicine plant.”
Interestingly, soil and roots were also found to play an important role in removing air-borne pollutants. Micro-organisms that are found in the soil become more adept at using trace amounts of these materials as a food source, as they were exposed to them for longer periods of time. It is important to keep in mind that their effectiveness is increased if lower leaves that cover the soil surface are removed, so there is as much soil contact with the air as possible.
The final results from the NASA studies generated the recommendation that it is best to use fifteen to eighteen good-sized houseplants in six to eight-inch diameter containers to improve air quality in an average 1,800 square foot house. Keep in mind that the more vigorously the plants grow, the better job they will do.