More on Plant VOCs

A follow-up email from Susan McCoy at Garden Media Group offered some follow-up information on the my previous post related to Plants and VOCs (Sept. 6, 2009). My take on it was at least on the right track, unlike some others - but I figure the press release (and upcoming report) is a good opportunity to get some background from the actual scientific experts :



Here's the text from the letter from September 22nd, 2009:

"To Whom It May Concern,
There have been a number of recent discussions resulting from information taken out of context from an American Society of Horticultural Science press release concerning research conducted on plant volatiles in our laboratory at the University of Georgia.

The release indicated that indoor plants have been found to release volatile organic compounds (VOCs). Unfortunately the results were subsequently misrepresented on an internet site, giving the impression that it is undesirable to have plants in our homes and offices.

This could not be further from the truth. All living things give off VOCs; one of the simplest is
CO2 that we emit when breathing. Therefore, solely equating VOCs with “harmful” is totally inaccurate. The fragrance of a rose or the aroma of apple pie are each made up of volatile organic compounds.

The assumption that has incorrectly been made is that all VOCs are equal and are harmful.
Mankind has evolved over hundreds of thousands of years breathing VOCs from plants, nearly all of which are harmless at the concentrations encountered in nature. Unfortunately over the last 150 years there has been a logarithmic increase in the number of synthetic chemicals from other sources to which we are now exposed. A number of these are extremely harmful and in some cases, lethal. These undesirable volatiles represent a serious health problem that is responsible for more than 1.6 million deaths per year and 2.7% of the global burden of disease (WHO, 2002).

Critical questions with regard to VOCs include: What chemicals and what are their
concentrations? In the website account, much was made of a minute amount of volatiles derived from pesticides applied to the plants. In reality, these pesticide-derived volatiles emitted from the Peace lily represented less that four hundredth of one percent (0.038%) of the volatiles given off by the plant. Finding minute amounts of chemicals indicates the extremely high level of sensitivity of the analytical techniques but does not imply a potentially harmful situation.

Our research has shown that while plants give-off a small amount of harmless VOCs, they also
remove significant amounts of toxic VOCs from the air. The net effect is overwhelmingly positive. Plants in homes and offices are not only aesthetically pleasing, they can also increase the quality of the air we breathe and thereby the health of the inhabitants. As we continue to research and learn more about the potential of plants to remove harmful volatile compounds we should generate knowledge that will enhance our ability to create exceptionally healthy indoor environments.

Sincerely,
Stanley J. Kays, Professor
University of Georgia

More info and contact for Professor Kays can be found here and I will try to get my hands on the report and see if there are any nuggets of info out there. And thanks Susan for the heads up on this!

Plants + VOCs

A recent, somewhat hyperbolic title from Treehugger, "Bad Green: Some Indoor Plants Release Volatile Organic Compounds" provides a snippet from some recent research that mention, gasp, that plants, particularly indoor ones, release volatile organic compounds (VOCs). It's a strange conceptual notion indeed, as there has been much research and information on the ability of indoor plants to improve air quality - including removal of VOCs and reduction of sick-building syndrome. So should we chuck the plant on the desk, and more broadly stop any notion of incorporating plants into buildings in significant ways? Probably not.


:: Killer Peace Lily - image via Treehugger

Some explanation "But at least four popular varieties of house plants emit their own VOCs, according to the University of Georgia's Department of Horticulture. Scientists there studied plants in glass jars and found 23 VOCs in the Peace Lily, 16 in the Areca Palm, 13 in the Weeping Fig and 12 in the Snake Plant. Sources included pesticides used in production of the plants, micro-organisms living in the soil and the plastic pots the plants called home, researchers say. The emission rates were higher during the day than at night, and several of the VOCs detected are known to harm animals."

It's not necessarily big news that plants give off VOCs... as plants are organically based and release compounds that are volatile (i.e. they vaporize readily into the air) through the normal process of metabolism. In fact one of the more readily occurring VOCs in nature is methane, which is produced in large quantities in wetlands. While not necessarily toxic, it is a player in global warming, so we should probably indict this as well while we're at it.

The difference between naturally occurring VOCs and synthetics are . Also a review of the study results identified that the primary VOCs from indoor plants were terpenoids, which are a somewhat innocuous form that provides a number of uses - and are particularly descriptive in having strong aromas. For instance the smell of such items as cinnamon, cloves, ginger, and eucalyptus is caused by the terpenoids present in these plants. Without these our sensory world would be much more bleak.


:: terpenoids look scary in molecular form - image via Wikipedia

Conversely a number of VOCs we are commonly bombarded with indoors, particularly in new construction, are related to paints, adhesives, solvents, cleaning agents, caulks, wood products, carpets and sealants, and their lovely sounding components of toluene, styrene, xylene and ethylbenzene. As it's easy to tell from a fresh walk down the halls of a new (even sometimes low-VOC green) building, as chemicals off-gas from these materials and invade our smell centers in negative ways, something foul is going on. And, as mentioned in the report, it is likely the major issues with VOCs and indoor plants come from off-gassing of worse compounds from the man-made plastic pots, and pesticides used in growing of the plants... as well as microorganisms in soils and growing media.

This is another compelling reason for a holistic transformation of the landscape and nursery industry to include the whole picture and not just assume that plants are good or bad. While this doesn't say that there isn't something to this idea of VOCs from plants (it's natural) - let's not jump to quick and overwrought conclusions about the perils of house plants without a bit of context and further exploration. I think the precautionary principal is fine, but to eliminate indoor vegetation without some more focused study on impacts is pretty poor form, particularly when many materials used in building and landscape construction are known to be bad, yet still are industry standard.

I'm willing to be that when the overall accounting is done, exterior plants and wetlands probably have a net benefit to our environment, and indoor plants will win out in the search for better indoor air quality. Just a hunch.

More Fake Trees

And They're Pretty Handy if we are Attacked by Giant Interstellar Swarms of Flies:


:: image via Inhabitat

Via Inhabitat: "A report published last Thursday from the Institution of Mechanical Engineers (IME) suggested that a forest of 100,000 artificial “trees” could be “planted” near depleted oil and gas reserves to trap carbon in a filter and bury it underground. The carbon suckers look more like fly swatters than actual arbors, but researchers say that once fully developed, the “trees” could remove thousands of times more carbon than a real tree."

Oddly enough, these even make our typical interstate highways look better. Then again flyswatters, although removing lots of carbon, don't have the multiple benefits of real vegetation.


:: image via Inhabitat

Jay Walker's library: something to covet.

Wired did a piece on Jay Walker, a technology millionaire and his library of awesomeness.

It is a mix of old styled library, historical science museum and a geek-fest. Walker has everything from an actual Sputnik satellite to an Enigma machine and various medical oddities.

There are more images in the Wired article including more views of the library and of various ancient books and artifacts.