Could the trailing fronds of a Boston fern or the glossy foliage of the dracaena plant clean the air in your home or office? The Internet’s packed with claims that these and other common, easy-to-grow houseplants have the power to significantly reduce levels of toxics, such as benzene, formaldehyde and trichloroethylene (TCE), that off-gas from newer building materials, rugs, wallpaper, furniture and even fabrics.

Related: Clearing the Air: 3 Dangerous Pollutants in Your Home

The concept of using plants to improve air quality is popular in Japan, where hospitals and businesses place foliage groupings called “ecological gardens” in common areas and offices. It’s also trendy in India. A 2008 government study found lower levels of breathing problems and eye irritation in a New Delhi tech company that brought in 1,200 plants to clear the air.

But before you head to the plant store on an environmental clean-up mission, here’s the rest of the story. Truth is, research into the air-clearing power of plants has yielded mixed results, especially under real-world conditions. And if you or a loved one has asthma or another breathing problem, potted plants could make things worse.

What you should know

Plants can clean the air, a little. Some of the most extensive research on plants’ effects on air quality has been funded by the U.S. National Aeronautic and Space Administration (NASA). NASA was looking for ways to remove toxins from the air in long-term space colonies of the future. In one widely cited study, NASA-funded researchers found that plants such as dracaena, Gerber daisy, potted chrysanthemums, mother-in-law’s tongue and Peace lily did, indeed, remove impressive amounts of benzene, formaldehyde and TCE from the air.

yellow chrysanthemumsyellow chrysanthemums (Photo: Maya Kruchankova/Shutterstock) 

But the experiments were run in sealed chambers to mimic conditions on a spacecraft, not in the typical home or office with fresh air circulating through windows, doors and vents. And at least some of the plants were grown over special activated charcoal air filtration systems instead of in conventional containers.

Strategically placed plants might help a bit in an office, or at least make you feel happier and more productive. In an intriguing Pennsylvania State University study, snake plants, spider plants, and golden pothos reduced levels of ozone, a component of lung-harming smog that’s also a surprising indoor pollutant. Ozone is released by copy machines, laser printers and some electrostatic air purification systems, contributing to indoor ozone that can trigger lung inflammation and reduce lung function. But in real-world studies in office buildings in Arlington, Virginia and Perth, Australia, plants didn’t make a difference in levels of benzene, TCE, toluene or xylene.

Research does show, consistently, that green plants in an office can boost your mood. In a 2014 study from the UK’s Cardiff University, productivity increased 15 percent when green leafy plants were added to the décor of a spare, modern office building. Workers felt greater satisfaction and said they could better concentrate, too. In a study from Taiwan, workers in a windowless office felt less anxious and stressed when they shared the space with a houseplant or two.

These plants performed best in research studies. A 2009 review of plant research published in the journal Proceedings of Healthy Buildings concluded that greenery probably won’t have much of an impact in most homes and offices. Opening a window works better. But if you’re still interested in growing plants that demonstrated air-cleaning properties under lab conditions, the journal Environmental Health Perspectives suggests these easy-to-maintain types:

  • areca palm (Chrysalidocarpus lutescens)
  • lady palm (Rhapis excels)
  • bamboo palm (Chamaedorea erumpens)Boston fern
  • rubber plant (Ficus elastica
  • dracaena (Dracaena decremensis, aka Janet Craig)
  • English ivy (Hedera helix)
  • dwarf date palm (Phoenix roebelenii)
  • ficus (Ficus macleilandii aka Alii)
  • Boston fern (Nephrolepis exaltata aka Bostoniensis)

Boston fern (Photo: KPG Payless2/Shutterstock)

  • Peace lily (Spathiphyllum wallisii)

Tend plants with care if someone in your household has asthma or a respiratory allergy. Mold and mildew on the surface of the soil could trigger an allergic reaction, but usually only when the dirt is disturbed, according to the Asthma and Allergy Foundation of America. Mold and mildew in dead foliage can do the same, If allergies or asthma are severe, some experts recommend getting rid of house plants entirely.

Related: Ban These 7 Allergens from Your Home

Sari Harrar is an award-winning health, medicine and science journalist whose work appears in Dr. Oz The Good Life magazine, Good Housekeeping, O--Oprah Magazine, Organic Gardening and other publications.