Several common houseplants can absorb airborne pollutants through their leaves and roots, but the effect in a real home is far smaller than most people expect. The original NASA research from 1989 tested plants in small, sealed chambers and found they removed chemicals like formaldehyde, benzene, and trichloroethylene. Those results are real, but scaling them to an actual living space tells a very different story.
What NASA Actually Found
The 1989 NASA study, conducted in partnership with the Associated Landscape Contractors of America, placed individual plants inside sealed chambers and measured how well they absorbed three specific pollutants: benzene (found in plastics and synthetic fibers), formaldehyde (released by furniture, flooring, and cleaning products), and trichloroethylene (a solvent used in adhesives and paints). The plants did remove these chemicals, sometimes impressively. Spider plants, for instance, have shown formaldehyde removal efficiency up to 95% in high-concentration chamber tests. Peace lilies removed about 79% of formaldehyde in 24 hours in similar setups.
The catch is that these chambers were tiny, sealed environments with no ventilation. Your home is neither tiny nor sealed. Air constantly cycles in from outside through windows, doors, HVAC systems, and even small gaps in walls. That circulation already dilutes indoor pollutants far faster than a few potted plants ever could.
Plants That Tested Well
Despite the real-world limitations, certain species consistently perform better than others in lab conditions. If you want plants that at least contribute some filtering alongside their other benefits, these are the ones with the strongest data behind them.
Spider plant (Chlorophytum comosum) is one of the most studied species. Research shows a single pot reduces formaldehyde by about 0.0071 mg/m³ over 24 hours, and individual leaves can absorb roughly 0.005 ppm of formaldehyde each. It’s also one of the easiest houseplants to keep alive, tolerating low light and inconsistent watering.
Peace lily (Spathiphyllum) absorbs formaldehyde, benzene, and trichloroethylene. In chamber studies, it removed about 79% of formaldehyde and roughly 29% of hexane in 24 hours. It prefers indirect light and consistent moisture. One important note: peace lilies are toxic to cats, causing oral irritation, drooling, and vomiting if chewed on.
Snake plant (Dracaena trifasciata) uses a type of photosynthesis called CAM, which means it opens the pores on its leaves at night instead of during the day. This allows it to convert carbon dioxide to oxygen while you sleep. That said, the Royal Botanic Gardens at Kew notes you’d need to fill your room with snake plants to get any noticeable oxygen boost. Snake plants are also toxic to dogs and cats.
English ivy, pothos, rubber plants, and various dracaena species all appeared in NASA’s original testing with positive results. English ivy, pothos, and dracaena are all toxic to pets if ingested, causing symptoms ranging from mild drooling to more serious gastrointestinal distress.
The Reality Check: Plants vs. Ventilation
A 2019 review published in the Journal of Exposure Science and Environmental Epidemiology examined 12 studies and 196 individual experiments. The researchers converted each result into a “clean air delivery rate,” the same metric used to evaluate mechanical air purifiers. The median rate for a single potted plant was 0.023 cubic meters per hour. For context, your home’s normal air exchange with the outside already replaces indoor air at a rate roughly once per hour.
To match that natural ventilation, you would need between 10 and 1,000 plants per square meter of floor space. In a typical bedroom, that’s not a few pots on a windowsill. It’s a jungle so dense you couldn’t walk through it. Michael Waring, the Drexel University environmental engineer who led that analysis, put it bluntly: the air-cleaning effect of houseplants in a real building is “irrelevant” compared to simply opening a couple of windows.
This doesn’t mean the NASA study was wrong. Plants genuinely do absorb volatile organic compounds. The problem is one of scale. A sealed 12-cubic-foot chamber has no air exchange competing with the plant. Your living room does.
What Plants Actually Do for Your Home
The scientific consensus has shifted away from recommending plants as air purifiers. Researchers who reviewed the evidence now suggest focusing instead on plants’ well-documented effects on mood, stress, and productivity. Studies on biophilic design (incorporating natural elements into indoor spaces) consistently show that having plants nearby reduces perceived stress, improves focus, and makes people report higher satisfaction with their environment.
Plants also add humidity to a room through transpiration, which can be helpful in dry climates or during winter heating season. And some species, like snake plants, do produce oxygen at night, even if the amount is too small to measurably change your sleep quality.
If air quality is your primary concern, a HEPA air purifier will outperform any number of realistic houseplants by orders of magnitude. Reducing the sources of pollution (choosing low-VOC paints, ventilating new furniture, avoiding certain cleaning products) is even more effective than filtering the air after the fact.
Pet Safety
Many of the plants most commonly recommended for air purification are toxic to dogs, cats, or both. The list includes English ivy, pothos, philodendrons, aloe vera, rubber plants, jade, dracaena, sago palm, and snake plants. Symptoms of ingestion range from mild oral irritation and drooling to vomiting, diarrhea, and in the case of sago palm, potentially fatal liver damage.
If you have pets and want plants that offer some filtering ability, spider plants are a safer option. Boston ferns, areca palms, and certain orchids are also non-toxic to cats and dogs, though their air-cleaning data is thinner. Placing toxic plants on high shelves or in rooms your pets can’t access is another practical approach, but cats in particular are creative climbers.
A Realistic Approach
Enjoy houseplants for what they genuinely deliver: a more pleasant living space, a calming visual element, a small contribution to humidity, and yes, some minor absorption of airborne chemicals. Just don’t rely on them as your air quality strategy. A spider plant on your desk and a peace lily in your living room will make your home feel better. For cleaner air, open your windows when outdoor conditions allow, run an air purifier if pollution is a concern, and address the sources of indoor chemicals directly.