This is a benefit of houseplants, that for the most part, has been largely ignored, but the health issues are potentially astronomical. We spend as much as 90 percent of our time indoors, breathing indoor air that often contains a diverse range of volatile organic compounds (VOC), many of which are toxic.
Houseplants can absorb those VOCs. To determine the best air-purifying houseplants, University of Georgia horticulturalists Stanley Kays, Bodie Pennisi, and D.S. Wang evaluated 32 plant species. Of the species tested, purple waffle plant (Hemigraphis alternate) best removed VOCs from the air. Other species with superior filtering abilities were English Ivy, Purple Heart, foxtail fern and wax plant.
In the study, the plants were tested for their ability to remove benzene, toluene, octane, trichloroethylene and a-pinene, all considered toxic. Plant specimens were placed in sealed glass containers. The VOC levels within were monitored over a six-hour period.
Poor indoor air quality can trigger allergies and asthma and cause fatigue and headaches. More than 300 volatile organic compounds have been identified as indoor contaminants.
These compounds come from carpet, wood panels, paint, people, pets, and various other sources. Benzene and toluene come from newspapers, schoolbooks, electric shavers, portable CD players, liquid waxes and some adhesives.
VOCs also emanate from home electronic equipment (which we have more of than we used to), furniture, carpet and construction materials.
Most of these compounds are readily absorbed into our bodies. Bad indoor air can result in new house syndrome and sick building syndrome that can cause a diverse cross-section of ailments in those exposed.
Before testing plants, the researchers conducted tests in three older, upper-middle-class homes in Athens, Ga. Older homes are often more drafty than newer homes which are built tighter to better insulate them.
The results were shocking, according to Dr. Kays. All three homes had surprisingly high levels of organic compounds in the air. These were older homes. So if the levels are high there, then it’s probably widespread in newer homes.
Not all VOCs are toxic, according to Dr. Kays, but the lack of information about chemical toxicity and an affordable method of measuring indoor air quality makes assessing their presence more difficult.
The researchers recommend adding a cross-section of plants, one per 100 square feet of living space. Using active charcoal filters in heating and air conditioning systems helps, too.