Several common houseplants can absorb airborne chemicals like formaldehyde, benzene, and other volatile organic compounds (VOCs) through their leaves and root systems. The most studied include snake plants, spider plants, peace lilies, and various palms. But before you stock up, there’s an important caveat: the air-cleaning effect of a few potted plants in a normal-sized room is far smaller than most people assume.
How Plants Actually Clean the Air
Plants pull pollutants out of the air through three different routes, and the leaves do most of the heavy lifting. Tiny pores on leaf surfaces called stomata open to take in carbon dioxide for photosynthesis, and airborne chemicals hitch a ride in the process. Research shows that roughly 75 to 80 percent of common pollutants like benzene, toluene, and xylene enter the plant through these pores. The remaining 20 to 25 percent gets trapped in the waxy coating on the leaf surface, which is especially useful at night when the stomata close.
The second route is through the soil. Bacteria living around the plant’s roots break down pollutants that settle into the growing medium. The plant actually encourages this by releasing sugars, amino acids, and enzymes that feed these microbes and speed up their ability to degrade chemicals. Microbes on the leaf surfaces also help, detoxifying some of what the leaves absorb before passing the rest down to the root zone for further breakdown. In lab studies, this microbial activity in the soil has consistently been identified as the primary driver of VOC removal over time.
Plants With the Strongest Research Behind Them
NASA’s well-known 1989 study tested plants against three specific chemicals: benzene, trichloroethylene, and formaldehyde. These are among the most common indoor pollutants, released by everything from paint and cleaning products to furniture, printers, and dry-cleaned clothing. The EPA notes that indoor concentrations of many VOCs run up to ten times higher than outdoor levels. Since that study, dozens of plant species have been tested against an expanded list including xylene, toluene, ammonia, and acetone.
Snake Plant
The snake plant (also called mother-in-law’s tongue) is one of the most popular choices because it’s almost impossible to kill and works around the clock. Unlike most houseplants, it continues producing oxygen and absorbing pollutants at night, making it a common pick for bedrooms. It has demonstrated removal of formaldehyde, benzene, trichloroethylene, and xylene in chamber studies.
Spider Plant
Spider plants are among the most tested air-purifying species. In early NASA research, a single spider plant in a small pot absorbed 3,300 micrograms of carbon monoxide over a six-hour period under light. The same study found it could remove over 99 percent of nitrogen dioxide from a small sealed chamber in six hours. These are combustion gases that come from gas stoves, fireplaces, and attached garages.
Peace Lily
Peace lilies are frequently cited for their ability to tackle a broad range of pollutants, including formaldehyde, benzene, xylene, toluene, and ammonia. They’re one of the few commonly available houseplants tested against ammonia, which is found in many cleaning products. They do well in low light, making them practical for rooms without large windows. One note for pet owners: peace lilies are toxic to cats.
Palms
Bamboo palms (also called parlor palms) and areca palms both appeared in NASA-era research and are effective against formaldehyde. They’re also among the best options for homes with pets, as both are non-toxic to dogs and cats. Their large leaf surface area gives them more capacity to interact with airborne chemicals.
Other Notable Species
Philodendrons, pothos, rubber plants, English ivy, and dracaena have all shown VOC removal in lab settings. Boston ferns are a good pick for humid spaces like bathrooms. Gerbera daisies performed well in the original NASA study and add color. Each of these works through the same basic mechanisms, with differences in which specific chemicals they handle most efficiently and how much leaf surface area they offer.
The Catch: Lab Results vs. Your Living Room
Here’s where the story gets complicated. Nearly all the impressive numbers you see cited online come from sealed chamber experiments, where a single plant sat in a small airtight space with a known dose of a chemical. Your home is not a sealed chamber. Air moves in and out through windows, doors, HVAC systems, and gaps in the building envelope. A 2019 review by environmental engineers at Drexel University recalculated the data from years of plant studies using a standardized measure called clean air delivery rate (CADR), the same metric used to evaluate air purifiers. Their conclusion was stark: the rate at which plants removed VOCs was orders of magnitude slower than the normal rate of air exchange in a building.
To match even the modest air-cleaning effect of opening a couple of windows, you would need between 100 and 1,000 plants per square meter of floor space. The American Lung Association put it in more concrete terms: roughly 680 plants in a 1,500-square-foot home. That’s not a living room; that’s a greenhouse.
This doesn’t mean the research is wrong. Plants genuinely do absorb these chemicals. The issue is scale. A few potted plants simply can’t process air fast enough to make a measurable difference in a real room with real ventilation. Active botanical biofilters, systems that use fans to push air through plant root zones, show much more promise because they dramatically increase the rate at which pollutants reach the soil microbes that do the real work. But those are engineered systems, not a pothos on your bookshelf.
What Plants Can and Can’t Replace
If your main goal is reducing indoor air pollution, the most effective steps are source control (choosing low-VOC paints, storing chemicals in ventilated areas, not idling a car in an attached garage) and ventilation (opening windows, maintaining your HVAC system). A standalone air purifier with a good filter will clean more air in an hour than a dozen houseplants will in a week.
That said, houseplants aren’t useless. They increase humidity, which can help with dry air in winter. They’re associated with reduced stress and improved mood in multiple studies. And in tightly sealed spaces with poor ventilation, like a small office with no windows, even modest VOC absorption adds up over time. The benefits are real. They’re just not a substitute for proper ventilation or filtration.
Pet-Safe Options
Several of the most commonly recommended air-purifying plants are toxic to dogs or cats. Snake plants, pothos, philodendrons, English ivy, aloe vera, rubber plants, jade plants, sago palms, and dracaena can all cause symptoms ranging from mild illness to serious toxicity if chewed or ingested. Peace lilies are specifically toxic to cats.
If you have pets, stick to these tested alternatives:
- Spider plant: non-toxic to both dogs and cats
- Bamboo palm: safe for pets, tolerates shade well
- Areca palm: entirely pet-friendly
- Boston fern: safe and thrives in low light and humidity
- Prayer plant: non-toxic, does well in dim spaces
- Money tree: listed as non-toxic by the ASPCA
- Gerbera daisies: safe for dogs and cats
- Orchids: safe for both species
- Most succulents: Echeveria and Haworthia are safe, but avoid aloe
Be cautious with anything labeled as a fern, since some plants marketed as ferns (like asparagus fern) aren’t true ferns and are toxic.