Spathiphyllum sp.

peace lily

Plants provide us a great service by transforming the carbon dioxide we exhale and produce from our energy-intensive activities into oxygen, which we can then breathe in. Quite a nice symbiotic relationship! In fact, the earth itself can be looked at as a breathing organism. In the winter, when many trees in the northern hemisphere lose their leaves, atmospheric levels of carbon dioxide increase dramatically (the planet “exhales”). Then in the spring, when the leaves come back out, carbon dioxide levels begin to fall dramatically (the planet “inhales”).

Beyond producing oxygen, plants, in conjunction with soil microorganisms, are also capable of filtering out volatile organic compounds (VOCs), which are produced from many indoor materials and have been linked to several human conditions and diseases such as respiratory illness, asthma, and cancer. Without the right amount of ventilation indoors, people who have hypersensitive respiratory systems can develop “sick building syndrome,” which includes irritation of the eyes, nose, and throat, dizziness, headaches, etc. Some notable VOCs that plants and soil microbes absorb include benzene (a known human carcinogen), formaldehyde, trichloroethylene, xylene, toluene, and ammonia. They are able to use the compounds they absorb by breaking them down into their constituent molecules for use in the manufacturing of other compounds for growth or defense.

We are exposed to many of these compounds on a daily basis, and since many people spend 70-90% of their time indoors where VOC concentrations can be up to ten times higher than outdoors, the long-term exposure required for negative health conditions to develop is almost a given. The U.S. Environmental Protection Agency has ranked indoor air pollution as one of the top five threats to public health, so people are beginning to realize the importance of indoor air quality and the potential use of plants to improve it. NASA compiled the first list of “air purifying” plants as part of their Clean Air Study, which sought to determine the best ways to clean air in space stations of volatile organic compounds. The peace lily is one of only two plants tested to remove all the VOCs tested, but it was not indicated what quantities of these compounds were removed. As far as we know, having ventilation to clean outdoor air is significantly better in terms of air quality than having plants in a room with little or no ventilation to clean outdoor air.

In addition to enhancing air quality for humans, houseplants provide aesthetics to interiorscapes and have a positive impact on the psychological well-being of those living or working within a building. When it comes to care for a peace lily, I'm pretty sure an image of this plant is to be found in most dictionary entries for "bulletproof."