The Homeowners Column

The Homeowners Column

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Can houseplants improve indoor air quality?

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Sandra Mason
State Master Gardener Coordinator
slmason@illinois.edu

Ahhh that new carpet smell. Unfortunately, these days "new stuff" can bring unhealthy air pollution. Combine "new stuff" with our winter habits of spending more time indoors and sealing our homes to keep the warm air in and the cold air out and the result can be an unhealthy situation.

In a recent article, written by University of Illinois Extension educator Chris Enroth, he explains how making a building airtight limits the exchange of fresh air; good for our pocketbook but bad in concentrating indoor air pollutants such as volatile organic compounds, that "new stuff" smell.

Enroth explains how volatile organic compounds, or VOCs, are present in many of our modern-day home furnishings and are a major source of indoor air pollution. Benzene is an example of a VOC found in many types of products such as ink, oils, paints, plastics, rubber, detergent, and dyes and is among the top 20 most widely used chemicals in the U.S. Homes with gas ranges or an attached garage typically have higher levels of benzene, as it is present in gasoline and vehicle exhaust.

Air filters can remove the majority of pollutants, but it is tough to rid a home of trace VOC elements. That's where indoor plants come in. Several studies have shown that many indoor plants have an ability to filter out VOCs and other air pollutants.

Enroth adds, "It is believed that most of these air pollutants are filtered out as part of the plant's photosynthesis activities. The air cleansing process is ongoing, so long as the plant is growing and healthy."

An ongoing study at State University of New York and recently reported in an American Chemical Society news release researchers examined five common houseplants and their efficiency at extracting VOCs from the air. Dracaena was the most effective houseplant at absorbing acetone, a commonly used VOC found in products like nail polish remover. However, bromeliads performed best in the removal of six of the eight VOCs tested in the study.

Despite these results, other researchers are casting doubt on the effectiveness of indoor plants in removing pollutants as outlined in an article entitled "Clearing the air about Indoor Plants" in American Horticultural Society's The American Gardener. Earlier research on indoor plants involved small sealed chambers. Critics point out that when these studies are scaled up to the size of an average 1,500-square foot home, it would take 680 plants to clean the air.

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Another problem is the amount of VOCs indoor plants are exposed to in a home or office. In one study, it was found that some homes contained up to 180 different airborne compounds. These chemicals are present in various concentrations and mix and interact in a nearly infinite number of ways, but most of the published research focuses on about a dozen different VOCs.

Does this mean you should toss your good-for-nothing fern on the compost pile?

"Of course not," Enroth says. "Houseplants have routinely been proven to improve our psychological well-being. Those living or working in buildings like hospitals, extended care facilities, offices, and single- or multi-family buildings report better productivity, learning, and reduced anxiety and depression when indoor plants are present.

"What's needed is more research on the effects of houseplants in homes and workplaces," Enroth explains. "We know indoor plants assist in air cleansing; we just don't know to what extent. Until that research becomes published, all gardeners agree: the world is a better place with more plants. So keep your rubber tree, spider plant, and dracaena. In fact, consider adding more indoor plants to your living and work environments."

For me, I figure I have 14 plants in my office right now, so all I need is about 212 more.

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