CHARLESTON, W.Va. -- The Harvard University Office of Sustainability's recent Green Tip of the Month comes, in large part, from a 1965 NASA study.

In "7 Plants to Improve Your Work and Living Space," the good folks from Harvard explain that houseplants reduce dust by as much as 20 percent and raise humidity by 5 percent in offices. Employees who worked in offices with live plants rated their job satisfaction higher, according to a study in Science Daily.

"Ideally, we would be spending large amounts of time outdoors in the sunshine and fresh air, but the truth is Americans spend approximately 90 percent of their time indoors," the sustainability office noted, based on an EPA study of buildings and their impact on the environment.

Luckily, NASA identified the top indoor plants that increase oxygen and filter out unwanted particles from the air in that 1965 study, "Foliage Plants for Removing Formaldehyde from Contaminated Air Inside Energy-Efficient Homes and Future Space Stations."

The study concentrated on formaldehyde as it was widely used in particleboard and plywood in the 1960s. The study was prompted by the adoption of energy-saving proposals in the 1960s to reduce ventilation rates in homes. NASA realized that similar problems occur with space travel and space stations.

One interesting part of the study showed that the potting soil absorbed atmospheric formaldehyde:

"This behavior was not surprising since soil is known to act as a sink for removing carbon monoxide and other chemicals from the air. The potting soil is not a sterile media either. Therefore, the natural microbial population will, in turn, metabolize non-refractive organics such as formaldehyde and restore the soil's capacity to absorb organics."

In layman's terms, the soil will get rid of the formaldehyde.

The initial study by NASA used golden pothos (devil's ivy), nephthytis (white butterfly or arrowhead vine) and sweet potato. Harvard has put together the list of seven plants that they suggest for conditioning your inside air (www.green.harvard.edu/green-tip):

Gerbera daisy: This genus of ornamental plants from the sunflower family is the fifth most popular flower in the world, according to www.proflowers.com. While the cut flowers are popular, the plants are better for cleaning up your atmosphere.

Snake plant:Sansevieria trifasciata is native to tropical West Africa from Nigeria east to the Democratic Republic of the Congo. It's often confused with the mother-in-law's tongue or Nassuavia serpens, which has sharper leaves.

Chinese evergreen:Aglaonema is a genus of about 40 species of rhizomatous evergreen plants native to the tropical rainforests of southeastern Asia. The sap is poisonous to humans and can cause skin irritation.

English ivy:Hedera helix plant can be invasive when used outdoors, but it's a great houseplant.

Spider plant:Chlorophytum comosum comes in solid and variegated forms and carry "plantlets" at the tips of the branches.

Peace lily: A popular houseplant, these are not a true lily but are from the Araceae family. They do not need excessive light or water to survive, and they remove benzene and other pollutants.

Bamboo palm:Chamaedorea sefritzii is also known as the reed palm; it thrives in shady spaces. It tops the list of plants best for filtering out both benzene and trichloroethylene as well as formaldehyde.

All of these are found in local shops, are easy to maintain and are long-lived.

Another unknown flower

Dear Sara,

Can you identify this plant? It was grown from a seed packet of mixed cut flowers. I have looked through all of my gardening books to no avail. It is now going to seed. I have seen goldfinches feeding on them. I enjoy your article in the Sunday Gazette-Mail.

-- Regards, Patricia McIntire, Hurricane

Any answers for Patricia?

Reach Sara Busse at sara.bu...@wvgazette.com or 304-348-1249.