Indoor Air Pollution: An Introduction for Health Professionals by the U.S. EPA

There is no bigger booster of indoor plants and urban greenscaping. I’ve devoted half my life to promoting this field in one way or another. What really disturbs me however is the distortion of fact that is used by many to promote the use of common, ordinary houseplants in drain hole pots.

Have you ever read this EPA document on the subject of Indoor Air Pollution? Note that the document is co-sponsored by The American Lung Association (ALA), The Environmental Protection Agency (EPA), The Consumer Product Safety Commission (CPSC), and The American Medical Association (AMA). You probably haven't read it simply because neither the mainstream media, the USDA Cooperative Extension Program nor the blogosphere ever references it.

I see either an article or blog post almost every day about the "ten plants to clean (or purify) the air in your home" or some such statement. In many cases, it is presented as medical advice. The people who write this stuff are essentially clueless about their free "medical advice" that is in reality a potentially harmful misstatement of fact. Some might even call it medical malpractice.

This is what the EPA and co-sponsors have to say about indoor houseplants.

You should know that most of this was initiated by the Plants for Clean Air marketing program conducted by the interior plantscaping industry. They did a good job of exploiting and misrepresenting the NASA research done by Dr. Bill Wolverton without ever really expanding their market. That is a story for a separate post in the future. 

When you see this type of misrepresentation, do everyone a favor and connect the author to this post or to the EPA document.

via www.epa.gov

Can plants control indoor air pollution

Recent reports in the media and promotions by the decorative houseplant industry characterize plants as "nature's clean air machine", claiming that National Aeronautics and Space Administration (NASA) research shows plants remove indoor air pollutants.

While it is true that plants remove carbon dioxide from the air, and the ability of plants to remove certain other pollutants from water is the basis for some pollution control methods, the ability of plants to control indoor air pollution is less well established.

Most research to date used small chambers without any air exchange which makes extrapolation to real world environments extremely uncertain. The only available study of the use of plants to control indoor air pollutants in an actual building could not determine any benefit from the use of plants.

As a practical means of pollution control, the plant removal mechanisms appear to be inconsequential compared to common ventilation and air exchange rates. In other words, the ability of plants to actually improve indoor air quality is limited in comparison with provision of adequate ventilation.

While decorative foliage plants may be aesthetically pleasing, it should be noted that over damp planter soil conditions may actually promote growth of unhealthy microorganisms. (editorial comment: over watering is a common result of tricky to learn drench and drain watering methods.)

Comments

[Ben Dunigan]

Yes ventilation will improve air quality more than house plants, however I don’t open the windows in my house or office for about 5 months a year in the extremely cold and hot months. But to argue they don’t remove pollution is incorrect. The University of Georgia’s Dr. Pennisi clearly shows that Plants can remove, Benzene, Toluene, Octane, TCE and α –Pinene. I ask what benefit is there really to prevent the use of indoor plants?

[Clem Cirelli, Jr.]

Obviously, live plants benefit the indoor environment and the people who inhabit indoor spaces in various ways, but air quality remediation is not one of them. No real-world building study to date has been able to demonstrate that plants are responsible for removing significant quantities of pollutants (I don't count CO2 as a pollutant, because it isn't one). And the growth-chamber experiments often cited as proof of their air-cleaning value used freshly installed plants grown in optimal lab conditions; those of us who are interior landscape professionals know full well that conditions in office buildings and other interior spaces rarely approach that level of optimal light, temperatures, humidity, etc. And many "professionally" maintained interior plants are not particularly well-cared-for or are metabolizing at a greatly reduced rate for various reasons. So this myth of plants as lean-green-air-cleaning-machines is simply sales puffery and nothing more.