Curt Swift, Ph.D.
Grand Junction Free Press Gardening Columnist

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January 31, 2013
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SWIFT: Air it out with houseplants

A January thaw. That's what I grew up with in New England. A time in mid-winter when the weather warmed and the rains came. The deep snow disappeared and sank into the ground or ran down the street into the frozen storm drain. The town crew would come along with their belching steam machine and thaw out the grates and pipes that allowed the rivers and lakes of snow water to drain away to the river.

That is what this past week reminded me of. The only thing missing here in Grand Junction was the crew and their steam machine.-

The January thaw we recently experienced helped replace soil moisture lost from the preceding dry, cold conditions. The rains also helped remove some of the pollutants from the inversion we were all exposed to. It may have seemed like the air wasn't that polluted but the reading of some of the pollutants were in the danger zone. Staying inside was recommended for some with respiratory problems. While that may have helped protect you from the air pollution outside your home, the air in your home could have been equally dangerous especially if proper filtration of that air was not occurring.

I recently installed a HEPA filter, one of the more expensive fine filtration types, in my heating system to help improve the quality of the air in our home. I'm sure that helped take out some of contaminates we were breathing. I'd suggest you do the same. Letting the fan run continuously would help clean even more pollutants out of the home's air but I would suggest you check with your heating contractor first to ensure you don't damage your heating system if you decide to let the fan run. I'd also suggest you consider adding more houseplants to your home's collection, especially those that are known to be most effective in removing and sequestering contaminants from the air.

Some of you may already have spider plant, dracaena, weeping fig, and philodendron in your houseplant collection. These plants are great in removing air pollutants. All you need to do is increase the number of these or add others such as pothos, peace lily (Spathiphyllum), gerbera daisy, Chinese evergreen, or English ivy. Even aloe plants have been found to be excellent air filtration plants.

The number of plants recommended for a home under 2,000 square feet is 15. This may seem like a lot of plants but when you space these six-inch pots around the home, you will be surprised how easy they fit in and the little space they take up. Of course, you could buy larger plants and have fewer plants.-

Benzene, formaldehyde and trichloroethylene were the target air pollutants of research reported in 1989 conducted by the Associated Landscape Contractors and American and the National Aeronautics and Space Administration. It was estimated at that time that 30 percent of all new and remodeled homes were suffering from "sick building syndrome." Homes were being made tighter to retain heat and reduce energy costs. This resulted in retaining pollutants as well as heat.

During the NASA/ALCA study the leaves, roots, soil, and associated microorganisms of plants were evaluated as a possible means of reducing indoor air pollutants. While the amounts of pollutants removed differed between plants all of the plants examined were effective in cleaning the air. The use of charcoal filters in addition to plants were found to remove cigarette smoke and organic solvents from the home's air.

All of the plants examined in this research study were low-light requiring species. They do well in areas where the light intensity is adequate for the comfortable reading of a book. When you add house plants to your indoor environment you can expect cleaner air and better health.


Dr. Curtis E. Swift is a retired horticulture agent with the CSU Extension. Reach him at or check out his blog at He owns Swift Horticultural Consulting and High Altitude Lavender.

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The Post Independent Updated Jan 31, 2013 02:45PM Published Jan 31, 2013 02:44PM Copyright 2013 The Post Independent. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.