Air Purifying Indoor Plants: The Science-Backed Guide
Air Purifying Indoor Plants: The Science-Backed Guide
Can houseplants actually clean your indoor air? The short answer is yes — with caveats. NASA's landmark Clean Air Study proved that certain houseplants remove harmful volatile organic compounds (VOCs) from indoor air. Here's what the science says, which plants perform best, and how many you actually need.
The Science: NASA's Clean Air Study
In 1989, NASA and the Associated Landscape Contractors of America published the Clean Air Study — research originally designed to find ways to purify air in sealed space station environments. The study tested common houseplants' ability to remove three major indoor air pollutants:
- Formaldehyde — Off-gassed from furniture, plywood, carpet, and cleaning products
- Benzene — Found in paints, detergents, tobacco smoke, and gasoline
- Trichloroethylene (TCE) — Released from adhesives, paint removers, and dry-cleaned clothing
The results were striking: certain plants removed up to 87% of indoor air toxins within 24 hours in sealed test chambers.
The Caveat
Later research (notably Dr. Michael Waring's 2019 meta-analysis) pointed out that NASA's tests were conducted in small, sealed chambers — not real-world rooms with ventilation. To replicate those results in a typical living room, you'd need an unrealistic number of plants (roughly 10–100 plants per square meter).
The practical takeaway: Houseplants do filter pollutants from indoor air, but they work best as a supplement to proper ventilation, not a replacement. Even so, there are real, measurable benefits: plants increase humidity, reduce stress hormones (cortisol), improve mood and focus, and yes — incrementally improve air quality over time.
The Best Air Purifying Houseplants
1. Peace Lily (Spathiphyllum)
The Peace Lily was the top overall performer in NASA's Clean Air Study, effectively removing formaldehyde, benzene, trichloroethylene, ammonia, and xylene — more pollutants than almost any other plant tested.
Pollutants removed: Formaldehyde, benzene, trichloroethylene, ammonia, xylene, toluene
Care: Low light to medium indirect. Droops dramatically when thirsty, bounces back after watering.
Note: Mildly toxic to pets if ingested.
2. Spider Plant (Chlorophytum comosum)
NASA found that Spider Plants removed 95% of formaldehyde from sealed test chambers within 24 hours. They're also one of the most resilient houseplants on the planet — and completely non-toxic to pets.
Pollutants removed: Formaldehyde, xylene, toluene, carbon monoxide
Care: Adapts to any light condition. Water when top half of soil is dry.
Bonus: Pet-safe — one of the few air-purifying plants that's non-toxic to cats and dogs.
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3. Pothos (Epipremnum aureum)
Pothos was one of the most effective plants in NASA's study for removing formaldehyde — the most common indoor air pollutant. It also tackles benzene and carbon monoxide. The fast-growing vines produce abundant leaf surface area, which is directly related to air-filtering capacity.
Pollutants removed: Formaldehyde, benzene, xylene, toluene, carbon monoxide
Care: Thrives in low to bright indirect light. Water when top inch of soil is dry. Nearly impossible to kill.
Why it's effective: Fast growth = more leaf surface area = more pollutant absorption.
4. Chinese Evergreen (Aglaonema)
Chinese Evergreens were highlighted in NASA's study for their ability to filter formaldehyde and benzene. They're also one of the best low-light plants available, making them perfect for air purification in dimly lit rooms where other plants can't survive.
Pollutants removed: Formaldehyde, benzene
Care: Low to medium indirect light. Water every 1–2 weeks. Extremely low-maintenance.
Best for: Bedrooms and offices with limited natural light.
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5. Philodendron
Philodendrons were included in NASA's study and performed well against formaldehyde — one of the most persistent indoor air pollutants. With their fast growth rate and abundant heart-shaped foliage, they provide significant leaf surface area for air filtration.
Pollutants removed: Formaldehyde
Care: Low to medium indirect light. Water when top 1–2 inches of soil dry. Fast-growing trailer or climber.
Versatile: Trail from shelves, grow in hanging baskets, or train up a moss pole.
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6. Dracaena
Multiple Dracaena species appeared in NASA's Clean Air Study, and they consistently ranked among the top performers. Dracaena Janet Craig was particularly effective at removing trichloroethylene, formaldehyde, and benzene.
Pollutants removed: Formaldehyde, benzene, trichloroethylene, xylene, toluene
Care: Low to medium indirect light. Allow top half of soil to dry between waterings. Sensitive to fluoride — use filtered water if leaf tips brown.
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7. Boston Fern (Nephrolepis)
Boston Ferns were found to be the most effective plant in NASA's study for removing formaldehyde specifically. They also act as natural humidifiers — their high transpiration rate increases indoor humidity, which helps your respiratory system and skin during dry winter months.
Pollutants removed: Formaldehyde, xylene, toluene
Care: Medium indirect light. Keep soil consistently moist. Loves humidity — mist regularly or place in a bathroom.
Bonus: Non-toxic to pets.
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8. Angel Wing Begonia
While Begonias weren't part of NASA's original study, they've been included in subsequent research on indoor air quality. Begonias are effective at absorbing VOCs and increasing indoor humidity through transpiration. Their lush, spotted foliage provides abundant surface area for air filtration.
Pollutants removed: Various VOCs through leaf absorption
Care: Bright indirect light. Water when top inch of soil is dry. 16+ varieties available.
Why we love them: Divine Roots' signature plant — stunning polka-dot leaves AND air-cleaning benefits.
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How Many Plants Do You Actually Need?
This is the question everyone asks — and the answer depends on your expectations:
- For measurable air quality improvement: NASA's recommendation was 1 plant per 100 square feet of living space. For a 1,000 sq ft apartment, that's roughly 10 plants.
- For noticeable humidity increase: A cluster of 5–10 plants in a room will raise humidity by 5–10%, which is meaningful during dry winter months.
- For mental health benefits: Even 2–3 plants in your immediate environment reduce stress hormones and improve focus (multiple studies confirm this).
- For dramatic air filtration: You'd need far more plants than is practical. Use plants as a complement to good ventilation, not a replacement.
Our recommendation: Start with 2–3 air-purifying plants in the rooms where you spend the most time (bedroom, home office, living room). Even a few plants create tangible benefits for mood, humidity, and incremental air quality.
Beyond Air Purification: The Full Health Benefits of Houseplants
Stress Reduction
A 2015 study in the Journal of Physiological Anthropology found that interacting with houseplants reduced physiological stress (measured by blood pressure and heart rate variability) compared to working on a computer. Simply being near plants lowers cortisol levels.
Improved Focus & Productivity
Research published in the Journal of Environmental Psychology found that offices with plants saw a 15% increase in productivity compared to lean, plant-free offices. Plants in your workspace aren't decoration — they're a performance tool.
Better Sleep
Plants in the bedroom can improve sleep quality by increasing oxygen levels and humidity during the night. Peace Lily and Spider Plant are particularly effective bedroom companions.
Natural Humidity
Houseplants release moisture through transpiration, naturally increasing indoor humidity. This is especially beneficial during winter when heating systems dry out indoor air, leading to dry skin, irritated sinuses, and respiratory discomfort.
Where to Place Air-Purifying Plants
- Bedroom: Peace Lily, Spider Plant, Chinese Evergreen — quiet air purification while you sleep
- Home Office: Pothos, Philodendron, Dracaena — boost focus and filter screen-adjacent pollutants
- Living Room: Boston Fern, Angel Wing Begonia — high-traffic rooms benefit most from multiple plants
- Kitchen: Spider Plant, Pothos — filter cooking fumes and formaldehyde from cabinetry
- Bathroom: Ferns, Fittonia — humidity-loving plants thrive here and filter bathroom chemicals
Frequently Asked Questions
Do indoor plants really purify air?
Yes. NASA's Clean Air Study confirmed that certain houseplants remove VOCs like formaldehyde, benzene, and trichloroethylene from indoor air. However, the effect is supplemental — plants improve air quality incrementally but shouldn't replace proper ventilation.
Which plant purifies air the most?
In NASA's study, Peace Lily (Spathiphyllum) removed the widest range of pollutants. For formaldehyde specifically, Boston Fern was the top performer. Spider Plant also ranked highly across multiple pollutant categories.
How many plants do I need to purify a room?
NASA's guideline is 1 plant per 100 square feet. For a typical bedroom (150 sq ft), 2–3 air-purifying plants provide measurable benefits. For maximum impact, choose plants with abundant foliage (like Pothos, Philodendron, and Ferns) since more leaf surface area means more filtration.
Are air-purifying plants safe for pets?
Some are, some aren't. Spider Plant, Boston Fern, Calathea, and Parlor Palm are both excellent air purifiers AND non-toxic to pets. Pothos, Peace Lily, and Philodendron are effective air purifiers but mildly toxic — keep them out of reach of curious cats and dogs.
Do plants produce oxygen at night?
Most plants stop producing oxygen at night (they switch to respiration, consuming small amounts of oxygen). However, some plants — including certain succulents that use CAM photosynthesis — do release oxygen at night. The amounts involved are too small to meaningfully affect a room's oxygen levels either way.
Can air-purifying plants help with allergies?
Plants can help with some indoor allergens by increasing humidity (which reduces airborne dust) and filtering certain chemical irritants. However, some plants may worsen allergies if they develop mold in the soil or release pollen. Keep soil surfaces clean and avoid overwatering to minimize mold growth.
Ready to breathe easier? Browse our full Air Purifying Plants collection — every plant hand-selected for indoor air quality benefits.