University of Illinois Extension

Leafy Green Clean Air Machines

Midwest winters can be tough. Wind, sleet, snow and cold can all add up to miserable conditions for four to five months, Greg Stack, U of I Extension horticulture educator noted.

“To combat these conditions we put on layers of clothing, find the heavy coats, gloves and scarves in order to do battle with what Mother Nature throws at us,” said Stack. “The same holds true for our homes. Homeowners have found that in order to keep things nice and cozy inside they need to do things to reduce drafts and reduce the amount of energy spent to keep the house warm. So, up go the storm windows, increase the amount of insulation, and plug up any and all openings that let cold air in and warm air out.”

Today’s homes have gotten very energy efficient and older homes have been retrofitted to make them tighter with fewer openings for drafts to blow threw. In other words, they have become less leaky and drafty.

“This is good. But is it really? Today’s homes are also trapping more indoor air pollutants such as formaldehydes, benzenes and other gasses that are released when we use things like carpeting, paints, laminates, furniture and other man-made materials that make our homes look nice but also make the air inside the house not as healthy to breathe,” said Stack. “Older homes had plenty of leaks to provide some air exchange. Today’s new homes and upgraded older homes have become so tight that natural air exchange is greatly reduced or virtually eliminated.”

NASA, the agency we think of as being responsible for putting men on the moon and exploring the galaxy, has recently revealed a study that suggests that houseplants can help greatly when it comes to improving indoor air quality. NASA has often been at the front end of technology that finds its way into everyday life and using houseplants as “green air purifiers” is the latest.

So, how are houseplants and NASA connected? NASA has been researching ways to clean up the air in space stations and make the environment suitable for humans to live and work. While dong this research, NASA has found that many common houseplants can do some interesting things when it comes to cleaning up indoor air pollution.

“Plants absorb carbon dioxide and give off oxygen during the normal process of photosynthesis,” Stack explained. “They are also very efficient at absorbing things like benzene, formaldehyde and lots of other air pollutants associate with today’s energy efficient ‘tight’ homes. They not only clean the air but also help interior humidity as well as just make things more livable by adding some greenery to an otherwise lifeless interior.

“Everyone can agree that a plant in an office, shopping mall or home can make the space more ‘friendly.’ But now there is evidence that it can make it healthier.”

Many of the houseplants NASA has found to be really good at cleaning the air are also houseplants that are commonly suggested for low light interior spaces. Because of this they can adapt and grow very well inside the home.

So, what houseplants are on NASA’s list? It starts off with the common, almost everyone has one, spider plant. We see it in baskets, on the top of tables and probably has been with you since you took up residence in a dormitory.

The Peace Lily or Spathiphyllum is a durable houseplant and can grow to an impressive size indoors and provide flowers as well. The Pothos with its variegated leaves makes a nice basket plant and Philodendron selloem or split leaf philodendron has large impressive leaves. Dracaena or corn plant with its narrow corn-like leaves that can be green or variegated provides a nice vertical accent. The cultivars that work well are ‘Massangeana’ and ‘Janet Craig’. And two very common, widely used house plants, snake plant, (Sansevieria) and weeping fig (Ficus benjamina) round out the list.

“Weeping fig can easily be grown to become an indoor tree,” he said. “What is good about this list is that all of these are readily available and commonly found at garden centers, home improvement stores and florists.”

NASA’s studies also suggest a six to eight inch size house plant (pot size) is capable of cleaning up the air in about 100 square feet of living space.

“In order to keep your clean air machine working efficiently, it is a good idea to keep the leaves clean,” he said. “Occasionally wiping the leaves with a damp cloth to remove dust and debris will make sure the plant is in ‘top operating form.’

“As we go into the winter months, think about adding a few house plants to your collection. Not only will they make the space a bit more friendly and livable but they can also help the air in the home to be a bit healthier to breathe.”