Most of us understand that chemicals are harmful to human health, and that they are off-gassed from common household items and products; items such as synthetic carpets (releases formaldehyde), petroleum products (release benzene), toys, chemical cleaners, paint, furniture with synthetic components and everything else that is synthetic!
The main indoor pollutants that affect health are formaldehyde, Volatile Organic Compounds (benzene and trichloroethylene or TCE), airborne biological pollutants, carbon monoxide and nitrogen oxides, pesticides and disinfectants (phenols), and radon.
These pollutants all contribute to ‘sick building syndrome’, which causes symptoms ranging from allergies, headaches and fatigue through to nervous-system disorders, cancer and death.
The good news is that there’s an easy and affordable way to combat the presence of pollutants we may be breathing in, and it comes right from the natural world. Plants can be used to both produce oxygen as well as remove common harmful chemicals from the air and break them down into harmless organic byproducts into the soil. So, how do houseplants clean the air? Plants absorb some of the particulates from the air at the same time that they take in carbon dioxide, which is then processed into oxygen through photosynthesis. But that’s not all—microorganisms associated with the plants are present in the potting soil, and these microbes are also responsible for much of the cleaning effect.
NASA, with assistance from the Associated Landscape Contractors of America, conducted a two-year study directed by Wolverton. His study of the interaction of plants and air found that houseplants, when placed in sealed chambers in the presence of specific chemicals, removed those chemicals from the chambers. Later, Wolverton expanded the study and assigned plants a rating from one to 10, based on a plant’s ability to remove chemical vapors or indoor air toxins, ease of growth and maintenance, resistance to insect infestation and the rate at which water evaporates from the leaves.
Through these studies, scientists have identified 50 houseplants that remove many of the pollutants and gases mentioned above. Here are some of the top contenders:
Madagascar Dragon Tree
A popular house plant that needs little attention. It cannot tolerate direct sunlight yet it does well in fairly well indirectly lit areas. It is more susceptible to becoming damaged from over watering than infrequent watering.
Pollutant removed: formaldehyde, xylene, and toluene.
One of the most popular clean air plants. Pet owners might want to select a different plant, however, as these are toxic to cats and dogs.
Pollutant removed: benzene, trichloroethylene, xylene and toluene.
This species (of which there are a variety of sub-species) thrives best in the shade and with only roughly one watering per week (must be chlorine free water) but never let the soil completely dry out. Just be aware that those flowers (like all flowers) do contribute some pollen and floral scents to the air, so you may want to avoid having a room full of them.
Pollutant removed: benzene, formaldehyde, acetone, ammonia and trichloroethylene.
In the NASA research, this plant was an air-purifying champion. Popular and inexpensive at garden stores, they can be planted outside after they’re finished blooming.
Pollutants removed: ammonia, benzene, formaldehyde, and xylene.
Spider plants are among the easiest houseplants to grow, making them a great choice for beginners or forgetful owners. A fan of bright, indirect sunlight, spider plants will send out shoots with flowers that eventually grow into baby spider plants or spiderettes.
Pollutants removed: formaldehyde and xylene
Ficus (weeping fig)
A hardy plant that ends up being between two and 10 feet tall. Grow this low-maintenance houseplant in bright, indirect light and allow the soil to dry out between waterings.
Pollutants removed: benzene, formaldehyde, and trichloroethylene
These plants prefer to clean the air from a cool location with high humidity and indirect light. They’re relatively easy to grow, but they do need to stay moist. Check the Boston Fern’s soil daily to see if it needs water, and give it a good soak once per month.
Pollutants removed: formaldehyde and xylene
Snake Plant (Mother in law's tongue)
This is one of the hardest houseplants to kill. Although it does need to be watered occasionally, it generally prefers drier conditions and some sun.
Pollutants removed: benzene, formaldehyde, trichloroethylene, and xylene.
A superstar of filtering formaldehyde, these palms thrive in full sun or bright light. Part of the reason they can filter so much air is that they can grow to be pretty big—as tall as four to 12 feet high, making them exciting (and pet-friendly) indoor additions.
Pollutants removed: benzene, formaldehyde, trichloroethylene.
In addition to being easy to care for, aloe makes some serious health claims. The plant’s leaves contain a clear liquid full of vitamins, enzymes, amino acids, and other compounds that have wound-healing, antibacterial, and anti-inflammatory properties, and there is some evidence that aloe may help skin conditions like psoriasis .
Pollutant removed: formaldehyde