“Since man’s existence on Earth depends upon a life support system involving an intricate relationship with plants and their associated microorganisms, it should be obvious that when he attempts to isolate himself in tightly sealed buildings away from ecological systems, problems will arise.” – NASA
Plants.
To some, this word may just give rise to thoughts of flowers blooming in the spring and grass in their lawns.. but quite frankly it should mean much more. Plants are literally the foundation on which all life exists. They provide oxygen, food, and hold together the face of our planet, no big deal or anything.. Trust me, I could go on for hours about these magical photosynthesizers but I’ll spare you. For right now I would like to focus on one aspect that may be very applicable to your daily life – air quality in your home.
According to the United States Environmental Protection Agency, indoor air pollution has been ranked among the top five risks to public health which is 
exacerbated when we realize people living in urban areas spend up to 85–90% of their time indoors. As the quote above from NASA states, the evolving habits of our society are further separating ourselves from the natural world. This is stripping us of benefits from plant life that we often forget even occur. NASA, universities, and other organizations have done research to find out if plants can be a simple, energy efficient solution to purify the air in homes.
Just to give a little background on how this research became of interest to society, let’s take it back to the 70’s. Our country was going through what some would consider an “energy crunch.” To compensate for this, housing construction adapted to maximize energy efficiency. Construction of buildings often included the use of superinsulation or other materials to hold in heat or air conditioning which ultimately reduced the flow of fresh air in and out of the building. This, combined with synthetic building materials that were emitting various chemical compounds, caused the workers in these buildings many documented health problems. These include rashes, irritated eyes, respiratory issues, and headaches. This phenomena became known as “sick building syndrome.”
Today, we don’t find ourselves in quite the exact situation but it is still similar. Like explained above, much of the common persons day is spent inside either at work or at home. Countless sources in our daily lives, including adhesives, ceiling tiles, particle board, furniture, paint, carpet, photocopiers and upholstery are often made from synthetic materials that give off various compounds into the air. Because our lifestyles are distancing ourselves from plant life and the natural world, air quality is likely to become compromised.
Fun fact: Much of the research has been conducted by former NASA research scientist Bill Wolverton, who was first interested in greenery as part of ecological life-support systems for space travel.
Common Household Air Pollutants
Benzene – very common solvent, present in very basic items including gasoline, plastics, tobacco smoke, rubber, dyes, and detergents. Benzene is an irritant to the skin and eyes among other mild symptoms when exposed to at low levels. Of course, at higher levels of exposure there are much more grim consequences that I don’t feel are necessary to go over for the purposes of this post.
Carbon monoxide – Often comes from tobacco smoke, fuel-fired furnaces, gas water heaters, fireplaces and woodstoves, gas stoves, gas dryers.
Trichloroethylene – This is a commercial product with a wide variety of uses particularly in metal degreasing and dry-cleaning industries but is also used in printing inks, lacquers, varnishes, adhesives and paints. The National Cancer Institute considers this chemical a potent liver carcinogen.
Formaldehyde – Is commonly found in all indoor environments. It is mostly reported to be found in particle board or pressed wood products. Other products such as grocery bags, waxed papers, facial tissues, and paper towels are treated with urea-formaldehyde.
Particulate Matter – Is a mixture of solid particles and liquid droplets found in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Once inhaled, these particles can affect the heart and lungs and cause serious health effects.
*Check out this short clip on plants and indoor air pollution – 60 Second Science
How Can Plants Help?
- Plant leaves, roots, and soil microbes work together in a symbiotic relationship to maintain the environment that surrounds them. They have the ability to absorb unwanted chemicals and release oxygen through their stomata (small opening on the leaf surfaces that allow gas exchange). Once plants have absorbed airborne pollutants through their stomata, they are metabolized and transported to their roots where microbes feed on and detoxify them (this is a very much watered down explanation, but you catch the drift).
- Plants also release volatile phytochemicals from their leaves which are important for controlling airborne microbes and mold spores in surrounding air.
- Another beneficial tendency plants possess is that they release water vapor through the leaves and into the air, raising humidity. High transpiration rates create convection currents that cause toxin-laden air to be pulled down into the soil around the roots, where microbes in the soil break down the gases into a source of food and energy.
All plants will absorb chemicals and purify the air to some extent, so I encourage owning plants of all kinds (of course..)! However, like humans, each plant species have their own strengths and weaknesses. Below I have compiled a list of the professionals at removing pollutants from the air.
Great House Plants for Air Quality
The following plants are chosen based on their ability to remove chemical-vapor, ease of growth and maintenance, resistance to pests, and rate of water evaporation (in no particular order). Most of the plants studied evolved in tropical or sub-tropical forests, where they received light filtered through the branches of taller trees. Because of this, their leaf composition allows them to photosynthesize efficiently under relatively low light conditions, which in turn allows them to process gases in the air efficiently and grow well in indoor environments.
English ivy
Ivy is native to light woodland areas which makes English Ivy houseplants thrive in an environment with bright filtered to low light. As for water, it prefers an evenly moist environment. These plants can often grow to be pretty long and elegant and even made into topiaries! However, if they get too long and leggy, feel free to take some scissors and go to town.. it won’t hurt a thing! Oh, and they are more than just a pretty face, these guys remove benzene, carbon monoxide, and formaldehyde.
Spider Plant
These tough little houseplants are not just easy to take care of, they are actually hard to kill. They don’t need much light at all so they are perfect for places around the house that don’t recieve much natural light. This also makes them perfect desk plants. They’re blooms are small white flowers at the end of aerial runners, which are followed by airborne plantlets (as show in the photo above). You’ll have more spider plants than you’ll know what to do with, I promise. In one study by University of Illinois, Spider plants removed 96% of the carbon monoxide present in an isolated plexiglas chamber!
Rubber Plant
These house plants enjoy part-sun to shade but will tolerate low light without much of a fuss besides growing a bit slower. That’s what makes them great for dim offices. Another reason they are great for offices is that they remove formaldehyde which is commonly found in the particleboard and formaldehyde-based glues holding those places together (desks, etc). They are also known to remove carbon monoxide according to the University of Illinois.
Palms (Areca, Lady & Bamboo varieties)
Due to their tropical origin, they enjoy indirect bright light but they are very adaptable to lower light conditions. They are known to release an abundant amount of moisture into the air as well as remove formaldehyde and carbon monoxide. Palms are extremely easy to care for and make a great statement to a corner of a room due to the heights they can grow to (as long as it isn’t a dwarf variety)!
Boston Fern
Boston ferns remove MORE formaldehyde than any other house plant. Not to mention, they are pretty good at removing benzene, too. They also release an abundant amount of moisture into the air. Bill Wolverton, and a former environmental engineer for NASA, is quoted saying, “they’re one of the best natural humidifiers of all houseplants tested.” Because of this, they require regular watering to replenish. If you have a particularly dry house it is recommended you mist and water frequently to reduce leaf drop.
Dracaena (Janet Craig, Red-Edged and Warneckii varieties)
This houseplant survives in dimly lit areas making them wonderful for indoor growing. Dracaena plants are near the top of the list at formaldehyde removers as well as rather efficient with absorbing benzene, trichloroethylene, and carbon monoxide. The specific variety, Janet Craig, is rated 5th on NASA’s top air purifying plants. They will tolerate a great deal of neglect, so if you aren’t a green thumb, this one is for you.
Golden Pothos
These are one of the easiest, most indestructible houseplants to grow. Overwater or underwater, odds are they’ll live to see another day. They have the ability to grow fast so they naturally look beautiful trailing from hanging basket or climbing creatively around a room. Although not in the front line of air pollutant removers, this plant is still relatively effective at absorbing some formaldehyde and other volatile compounds. One research study found that when placed in a plexiglass chamber with Carbon monoxide, Golden Pothos removed 75% of it!
Peace Lilly
Not many houseplants will consistently bloom indoors, but the Peace Lilly will! It’s known to be one of the best for formaldehyde removal. Other benefits of this plant are removing benzene, trichloroethylene, carbon monoxide, and volatile compounds released from cleaning products. Like the fern and palm, this Lilly also Releases an abundant amount of moisture into the air. They are tolerant of low light and thrives in part shade to shade.
Alii Fig (also known as, Ficus Alii)
These plants do well in bright indirect life and can survive in low light but will grow much slower. Don’t move this plant around! Ficus/Figs are very sensitive to location change and will drop a decent amount of leaves in an attempt to adjust. This may make it seem like a temperamental indoor plant but if you leave it do its own thing it will thrive for years!
Snake Plant
Personally, these are some of the hardiest plants I’ve ever owned! With their thick leaves, they are very resistant to under watering. They also do quite well in low light which is why you can commonly find these plants growing in malls and offices under nothing but daily incandescent lighting. Another interesting fact is that these plants are very efficient at producing oxygen at night making them a good candidate for a bedroom plant. To learn more about how that mechanism works, check out this link!
Philodendrons (heart-leaf, selloum, and elephant ear)
All varieties of philodendron are noted for their remarkable efficiency in producing oxygen and absorbing carbon monoxide! They also formaldehyde removers, especially when trailing varieties (heartleaf, etc) are allowed to grow extensively. Research has proved that with more surface area, chemical absorption increases. This is all the more reason to let these plants trail all over your house!
Soil.. yes, I SAID SOIL!
Soil and roots were also found to play an important role in removing air-borne pollutants. Micro-organisms in the soil become more proficient at using trace amounts of these materials as a food source, as they were exposed to them for longer periods of time. Their effectiveness is increased if lower leaves that cover the soil surface are removed, so there is as much soil contact with the air as possible. Another neat discovery that came from the NASA article is that potting soil is actually more effective at removing benzene than the foliage itself!
Final Thoughts…
The NASA studies generated the recommendation that you use 15 to 18 good-sized houseplants in 6 to 8-inch diameter containers to improve air quality in an average 1,800 square foot house. The more vigorously they grow, the better job they’ll do for you. Other things you can do to help the plants efficiency is cleaning their leaves. Wiping the dust off the leaves allows gases to easily move in and out of the stomata on the surface of the leaf.
I sincerely hope while reading you’ve learned something new, but even more importantly, have the wild urge to fill your entire house with plants!
Wildly Curious. 
I’d be lying if I said that you, Casey Shawver, did not give me the wild urge to fill my house with plants. This was a fantastical article, as usual!
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