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PRI's Environmental News Magazine

Breathing Indoors: What Helps?

Air Date: Week of April 19, 1996

Steve Curwood talks with retired NASA researcher and indoor plant expert Bill Wolverton about what common house plants have been found to help with improving indoor air quality.


CURWOOD: It's Living on Earth. I'm Steve Curwood. The air we breathe inside our homes and offices is often a good deal more polluted than what we find outside. In fact, the EPA has identified as many as 800 volatile organic chemicals swirling inside buildings. They seep from walls and ceilings; they're in our clothing, furniture, and carpets. But there's a simple and cheap way to offset many of these toxic gases: common house plants. Finding out which ones do the best job involves a good deal of research, the kind of painstaking work done by Dr. Bill Wolverton, an environmental scientist and retired senior researcher at NASA. He's been studying the cleansing effects of indoor plants for about 25 years.

WOLVERTON: My first interest, of course, was with NASA and looking into how one might develop a closed ecological life support system for future moon bases. And it led me to look back at planet Earth. How does the Earth sustain life? And it all boils down to green plants and the microbes that they culture on their roots. So that's what got me started looking at plants and particularly house plants, because they require low light and we can put those in buildings without requiring a tremendous amount of energy and lighting.

CURWOOD: Now, in our homes and offices, Dr. Wolverton, what are the greatest threats to indoor air quality?

WOLVERTON: Well back about 15 years ago with the energy crisis, we started to seal our homes and offices to make them more energy efficient. And at about the same time, we started to change the composition of materials in our homes and offices. Practically everything now, the desks, the furniture is made of synthetics. Also we started to use wall to wall carpeting which makes it nice, but unfortunately it gives off certain pollutants and particles. So what we've done over the years, in sealing up our home, we've created an unhealthy gas chamber inside our homes and offices.

CURWOOD: Now what can we do to counteract these effects and improve our air quality?

WOLVERTON: Well, answer is, take nature's living air filters, which are plants, design them in buildings or add them to buildings, and they will literally suck out these pollutants, absorb them, translocate them throughout the plant, break them down, or utilize the root microbes that they culture to help break them down. So it's a complicated process that the simple, innocent looking houseplant can do to help clean the air and hopefully save your health.

CURWOOD: And the five best plants that are easy to grow are?

WOLVERTON: Well, the ones that I prefer based on working with them for many, many years are the Peace lily, Areca palm, Lady palm, Ficus alii, and the Golden pothos.

CURWOOD: Now why are these better?

WOLVERTON: Number one is, they're very easy to grow. Number two is, they are among the top in removing undesirable indoor air polluting substances, such as formaldehyde. And number three is, they have what we call a high transpiration rate. In other words, they add healthy moisture to a room, and that is especially important in the winter time up in your part of the country where it's cold. The air gets dry and it makes you more susceptible. Your throat, nasal passage, dries out. You're more susceptible to these chemicals and to cold viruses and other things. So these plants, house plants, do a lot of good things for us in creating healthy indoor environments.

CURWOOD: Now I'm wondering, Bill Wolverton, just how many plants do I have to have in order to clean the air in my home or my office?

WOLVERTON: Well, that question has been asked so many times over the past 10 to 15 years, and we recommend that you use maybe 2 or hopefully 3 nice sized plants per 100 square feet.

CURWOOD: Well, I want to thank you for taking this time for us. My guest has been former NASA scientists Dr. Bill Wolverton. He's the author of the forthcoming book Eco-Friendly Houseplants. That will be published by Viking Penguin in the fall. Thanks so much.

WOLVERTON: Thank you. I've enjoyed it.



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