If you’ve ever wondered whether houseplants actually do anything for indoor air, you’re in good company. NASA’s Clean Air Study — conducted by Dr. B.C. Wolverton in 1989 (later published in 1999) — found that common plants can remove traces of formaldehyde, benzene, and other toxins from sealed chambers. For homeowners tired of stuffy bedrooms or musty basements, the question isn’t whether plants help, but which ones do the most work.

4 related posts

NASA Tested Plants: 20 · Top Purifier Mentioned: Peace Lily · Mold Reduction Claim: 78% · Common Lists: Top 10 · Beginner-Friendly Options: Spider Plant, Snake Plant

Quick snapshot

1Confirmed facts
2What’s unclear
  • Real-world effectiveness in open, ventilated homes versus sealed test chambers
  • Exact percentage reductions for individual toxins in typical residential conditions
3Timeline signal
  • NASA study originated circa 1989, published 1999 — research is decades old with limited recent replication
4What’s next
  • Growing interest in plant-air quality combos for allergy and asthma management

The table below summarizes the most commonly cited plant rankings from the NASA Clean Air Study research.

Most Cited Top Plant Mold Removal Leader NASA Plants Count Beginner Favorites
Peace Lily English Ivy 78% 20 Spider Plant, Snake Plant

Which indoor plant purifies the air the most?

Two plants consistently outrank the others in the NASA Clean Air Study: the Florist’s Chrysanthemum (Gerbera jamesonii) and the Peace Lily (Spathiphyllum). Both showed broad-spectrum removal of common household toxins in controlled chamber tests.

Peace Lily Benefits

The Peace Lily earns its spot through sheer versatility. According to CO2 Meter, it removes formaldehyde, benzene, trichloroethylene, xylene, and ammonia — five different compounds that off-gas from paints, furniture, and cleaning products. Beyond toxin removal, it absorbs excess moisture from the air, making it useful in bathrooms and kitchens where humidity tends to climb.

Snake Plant Effectiveness

The Snake Plant (Sansevieria trifasciata) takes a different approach. It targets formaldehyde, benzene, xylene, toluene, and nitrogen oxides, covering a slightly different chemical range than the Peace Lily. What sets it apart is its nighttime behavior: it continues releasing oxygen after lights go out, which some indoor gardening enthusiasts find useful for bedrooms.

Spider Plant Results

For beginners, the Spider Plant (Chlorophytum comosum) is nearly impossible to kill. It handles formaldehyde, xylene, and toluene with minimal fuss, and it thrives in temperatures between 55–75°F — typical room conditions in most homes. The trade-off is narrower chemical coverage compared to top-ranked plants.

What this means

If you have room for just one plant and want maximum toxin coverage, Peace Lily delivers the broadest chemical punch. Snake Plant works better for night-time oxygen output, while Spider Plant suits those who travel and forget to water.

What plant removes 78% of airborne mold?

English Ivy (Hedera helix) frequently appears on mold-control plant lists with claimed removal rates reaching into the 70–80% range against airborne spores. Some sources cite figures closer to 94% for mold spore reduction, though that specific percentage comes from limited, non-peer-reviewed reporting. The core mechanism is documented: English Ivy absorbs airborne mold particles and releases oxygen, creating conditions less friendly to mold growth.

English Ivy Capabilities

Unlike toxin-absorbing plants that filter chemicals, English Ivy tackles biological particles floating in the air. The Balcony Garden notes that its dense leaf structure catches mold spores, while root activity helps dry surrounding air. This dual action makes it particularly useful in damp basements, bathrooms, or poorly ventilated laundry rooms.

Specific Mold Studies

Reported mold reduction figures vary. Common claims cite around 78% reduction in airborne mold concentrations, though the exact methodology behind that figure isn’t always clear in garden publications. The underlying principle — that plants actively exchange air and can trap biological particles — has biological plausibility, but residential effectiveness depends heavily on room size, plant count, and ventilation rates.

Other Mold Fighters

Several other plants show similar moisture-control behavior. Boston Fern (Nephrolepis exaltata) absorbs humidity and discourages mold formation, according to The Balcony Garden. Palm varieties — including Areca palms, bamboo palms, and lady palms — also help control humidity levels, creating less hospitable conditions for mold spores.

The pattern shows that humidity-absorbing plants work best as supplements to proper ventilation rather than standalone mold solutions.

What plants detox the air?

The NASA research screened a dozen common houseplants against five target compounds: formaldehyde, benzene, trichloroethylene, xylene, and ammonia. Not every plant tackles all five, but most hit at least two or three.

Aloe Vera Toxin Removal

Aloe Vera (Aloe barbadensis miller) targets formaldehyde and benzene specifically — two common indoor pollutants from adhesives, solvents, and certain cleaning products. Its thick, gel-filled leaves store water, which means it tolerates irregular watering better than more delicate species. Beyond air purification, the gel has documented wound-healing properties, making it a practical addition to kitchens.

Top Detox List

Beyond Peace Lily, Snake Plant, and Aloe Vera, several other plants showed strong detox performance in the NASA research. Golden Pothos (Epipremnum aureum) handles formaldehyde, benzene, xylene, and toluene. Boston Fern targets formaldehyde and xylene. Chinese Evergreen (Aglaonema) removes formaldehyde and benzene. According to CO2 Meter, this breadth of options means most households can find at least one effective species suited to their light and care conditions.

NASA Validated Options

The full NASA list includes Bamboo Palm (Chamaedorea sefritzii) and multiple Dracaena varieties — cornstalk, Janet Craig, Red-edged, and Warneck — all showing measurable improvements in air quality under controlled conditions. University of Connecticut’s extension service documents these as part of the original Wolverton research portfolio.

The implication is that homeowners have diverse options beyond the most-cited top performers, which matters for low-light spaces where Peace Lily struggles.

What are NASA top 10 air purifying plants?

The “top 10” designation is partly editorial shorthand — the original Wolverton study tested roughly a dozen species, not exactly ten. The list typically prioritizes plants that removed multiple toxins efficiently in sealed chambers, with rankings varying slightly depending on which toxins researchers weighted most heavily.

NASA Study Overview

NASA scientists became interested in houseplant effects on indoor air quality because they needed ways to purify air in space stations — a closed system where even trace chemical buildup matters. Dr. Wolverton screened common houseplants from gerbera daisy to bamboo palm and tested their ability to remove household toxins. According to NASA Spinoff, the agency was looking for biological filtration solutions that could supplement mechanical air cleaners in confined environments.

Ranked Plant List

While no single canonical “top 10” list exists in the original study, garden publications commonly cite these plants: Peace Lily, Snake Plant, Spider Plant, English Ivy, Boston Fern, Aloe Vera, Golden Pothos, Chinese Evergreen, Bamboo Palm, and Dracaena. Chrysanthemum often tops individual toxin-removal rankings, while Peace Lily tends to rank highest for breadth of coverage.

Key Findings

One practical finding from the research: density matters. NASA recommended roughly one plant per 100 square feet of living space to achieve measurable air quality improvements — a ratio most single-plant owners don’t meet. University of Connecticut notes this suggests that casual plant ownership probably offers modest benefits, while serious air-purification goals require multiple specimens.

The NASA Spinoff publication also documents the BioHome at Stennis Space Center — an experimental 45-foot-long, 16-foot-wide structure that used common indoor houseplants as living air purifiers, demonstrating real-world application of the research principles.

What this means is that achieving meaningful air quality improvements requires a density of plants that most homeowners don’t maintain in typical living spaces.

What are low-maintenance indoor plants for clean air?

For plant beginners or frequent travelers, low-maintenance species reduce the risk of dead plants and failed air quality experiments. The two most frequently recommended options both appear on the NASA list while requiring minimal intervention.

Beginner Picks

Spider Plant tops most beginner-friendly air purifier lists because it tolerates inconsistent watering, survives in temperatures between 55–75°F, and adapts to both bright and low-light conditions. According to Ideal Home UK, it also absorbs excess moisture, which helps with condensation control in poorly ventilated spaces.

Snake Plant requires watering roughly every two to three weeks — far less than most houseplants — and tolerates low light without losing its air-purifying capabilities. Its vertical growth habit means it takes up minimal floor space while providing substantial leaf surface area for air exchange.

Care Tips

English Ivy, while not the lowest-maintenance option overall, requires watering only when the top inch of soil is dry, according to Gardening Know How. This makes it manageable for people who neglect their plants occasionally. The tradeoff is its climbing growth habit, which may require pot support or hanging arrangements.

Air Quality Impact

Low-maintenance doesn’t mean low-impact. Spider Plant removes formaldehyde, xylene, and toluene. Snake Plant handles formaldehyde, benzene, xylene, toluene, and nitrogen oxides. Both deliver meaningful toxin coverage without demanding daily attention.

Bottom line: Peace Lily delivers the broadest toxin coverage, but Snake Plant and Spider Plant give beginners reliable air-quality benefits without demanding green thumbs. English Ivy targets mold specifically, making it the choice for damp-basement dwellers or allergy sufferers.

Clarity section

What the research confirms

  • NASA’s 1989 study (published 1999) screened houseplants for toxin removal in sealed chambers
  • Peace Lily and Chrysanthemum ranked as top performers for broad-spectrum air purification
  • NASA recommended approximately 1 plant per 100 square feet for measurable effects
  • Common houseplants remove formaldehyde and benzene under controlled conditions
  • Several plant species emit oxygen at night, useful for bedroom placement

What remains uncertain

  • Exact percentage reductions in open, ventilated homes versus sealed test chambers
  • How plant count, room size, and air exchange rates interact in real residential settings
  • Whether specific mold removal percentages (78–94%) hold under varied conditions
  • Long-term effectiveness compared to mechanical air purifiers

Dr. Wolverton’s team was looking for biological filtration solutions that could work alongside mechanical air cleaners in confined spaces.

NASA recommended roughly one plant per 100 square feet of living space to achieve measurable air quality improvements.

The catch

The original NASA research was conducted in airtight chambers — not typical homes with opening doors, windows, and active air exchange. A single Peace Lily on a coffee table won’t replicate those results in a real living room.

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Additional sources

boredpanda.com, restopros.com, aquaconsult.be, youtube.com, housebeautiful.com

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Frequently asked questions

Do indoor plants really improve air quality?

Yes, but with caveats. The NASA Clean Air Study demonstrated measurable toxin removal in sealed chambers. Real-world effectiveness depends on plant count, room ventilation, and the specific chemicals present. Multiple plants (roughly 1 per 100 sq ft) are needed for noticeable effects in typical homes.

How many air purifying plants do I need?

NASA’s guideline suggests approximately one plant per 100 square feet of living space. A 300 sq ft apartment would need three or four well-placed specimens for equivalent coverage to the study conditions.

Can air purifying plants help with allergies?

Some plants — particularly English Ivy and Boston Fern — reduce airborne mold spores and control humidity, both common allergy triggers. However, plants are not substitutes for HEPA filtration or medical treatment for severe allergic conditions.

Are there air purifying plants for low light?

Snake Plant and ZZ Plant are among the lowest-light-tolerant air-purifying options, surviving in dim corners where other species would struggle. Both appear on NASA-adjacent plant lists for formaldehyde removal.

What toxins do common houseplants remove?

The most commonly removed compounds include formaldehyde (from adhesives, paints), benzene (from plastics, solvents), xylene and toluene (from inks, paints), trichloroethylene (from industrial solvents), and ammonia (from cleaning products). Coverage varies by species.

How often to water air purifying plants?

Spider Plant: every 7–10 days. Snake Plant: every 2–3 weeks. Peace Lily: when leaves start drooping slightly. English Ivy: when top inch of soil is dry. Overwatering causes more plant deaths than underwatering in most species.

Are peace lilies safe for pets?

No — Peace Lilies contain calcium oxalate crystals that can cause oral irritation, drooling, and difficulty swallowing in cats and dogs if ingested. Pet owners should choose pet-safe alternatives like Spider Plant or Boston Fern instead.

For homeowners choosing between mechanical purifiers and houseplants, the calculus is straightforward: mechanical units process large air volumes quickly and specifically target particles and gases. Plants offer slower, complementary benefits — toxin absorption, humidity control, and oxygen generation — that work best alongside, not instead of, proper ventilation. A well-placed collection of Peace Lilies and Snake Plants won’t replace an air purifier, but it won’t hurt either.