As the deep cold creeps in again this week, doors and windows are shut tight and your furnace is churning away, circulating warmed air throughout your house. It is also spreading through your house whatever is in the air. Certainly your furnace air filter traps many airborne particles, but adding a selection of houseplants to your rooms can give a little boost to indoor air quality.

Most middle school students can explain the basics of photosynthesis, but the gist is that, while we humans breathe in oxygen and expel carbon dioxide, plants do the opposite, making for a mutually beneficial relationship whereby we benefit from their oxygen output and they draw in our carbon dioxide output.

But in addition to carbon dioxide, chemicals such as formaldehyde and benzene from furniture and rugs, household cleaning products, exhaust fumes and renovation work also affect indoor air quality. In particular, installing new carpet and painting release chemicals. Although not a substitute for proper ventilation during home improvement projects, judicially placed houseplants (two 10-12 inch pots per 100 square feet of space) can help improve air quality by reducing the amount of some chemicals in the air.

Sign Up for E-News

In a report sponsored by NASA in 1989, plants were noted for their ability to reduce volatile organic compounds (VOCs) that cause "sick building syndrome." A list of air-filtering plants, derived from the study, can be found on Wikipedia. The table also notes what plants are toxic to pets and children.

For example, peace lilies, spider plants and snake plants all absorb formaldehyde, and English ivy, golden pathos and red-edged dracaena all reduce benzene. There are many articles online with information on specific houseplants and the chemicals they target. Here are just a few: Houseplants that Clean the Air; 10 Clean-Air Plants for Your Home; and 15 Houseplants for Improving Indoor Air Quality.

As we move toward more efficient house sealing to avoid energy waste, we should become more aware of what products and materials we are using in our homes that might be trapped inside. Houseplants are not a substitute for good ventilation, nor will they remove all chemicals--a good reason to think about just what chemicals are in your cleaning products--but they do contribute to air purification, and you get the added plus of bringing a little bit of nature's beauty into your home.

By Beth Lovejoy, on behalf of the Summit Environmental Commission