Best Indoor Plants for Air Quality

What NASA actually found about plants and air quality

Peace lily, snake plant, pothos, and spider plant remove measurable levels of VOCs from indoor air — benzene, formaldehyde, and trichloroethylene among them. The catch: NASA’s 1989 Clean Air Study tested plants in sealed chambers, not typical US homes.

The Clean Air Study is real science. NASA researcher B.C. Wolverton tested 19 common houseplants by exposing them in sealed chambers to known concentrations of specific volatile organic compounds and measuring removal rates over 24-hour periods. The results were genuine and peer-reviewed. Peace lily, English ivy, and Gerbera daisy performed best overall.

Where the popular claims get oversimplified: homes aren’t sealed chambers. Normal air exchange rates in US houses mean VOCs dilute faster than plants can remove them. A 2019 analysis by researchers at Drexel University calculated that you’d need roughly 10–100 plants per square foot of floor space for indoor plants to meaningfully compete with a home’s baseline air exchange rate.

That’s not a reason to skip air-purifying plants. It’s a reason to set accurate expectations. Six to eight plants in a 100-square-foot room will make a measurable difference, especially in a closed room in winter when windows stay shut. One or two plants on a shelf is more about aesthetics than filtration.

The top air-purifying plants for US homes

Peace lily: the top VOC performer

Peace lily (Spathiphyllum) removes more types of VOCs than any other plant in NASA’s Clean Air Study, including ammonia — which most other plants don’t filter.

Ammonia removal matters in US homes because ammonia is a common indoor pollutant from cleaning products, particularly floor cleaners and glass cleaners. Peace lily is the only commonly available houseplant that removes it in significant quantities.

Care requirements:

• Light: Tolerates low light but blooms better in medium indirect light. A north-facing window works. Direct sun burns the leaves.
• Water: Weekly during growing season (spring–fall), every 10–14 days in winter. Peace lily communicates clearly — it wilts dramatically when dry. Water when you see the droop.
• Temperature: Prefers 65–85°F. Cold drafts from AC vents damage leaves. Keep at least 2 feet from any AC vent.
• Humidity: Higher humidity improves performance and leaf health. Group plants together or use a pebble tray with water underneath the pot to increase local humidity.

Toxicity warning: Peace lily is toxic to cats and dogs. The calcium oxalate crystals cause oral irritation, drooling, and difficulty swallowing. Keep out of reach of pets. For pet-safe alternatives, spider plant and Boston fern remove formaldehyde without toxicity risk.

Snake plant: the most practical choice

Snake plant (Sansevieria, now reclassified as Dracaena trifasciata) combines meaningful air-purifying ability with near-indestructible care requirements — it thrives on neglect in a way no other air-purifying plant can match.

Snake plant is unique among air-purifying plants because it performs Crassulacean Acid Metabolism (CAM) photosynthesis: it absorbs CO2 and releases oxygen at night rather than during the day. This makes it a better bedroom plant than most others that absorb CO2 at night when you’re sleeping.

NASA recorded it removing benzene (28% removal in 24 hours in sealed chamber tests), formaldehyde, trichloroethylene, and xylene.

Care:

• Light: Tolerates very low light — 25 foot-candles, the equivalent of a room with no windows. Grows fastest in medium to bright indirect light.
• Water: Water once a month in winter, every 2–3 weeks in summer. The most common way to kill a snake plant is overwatering. The leaves show the problem clearly: soft, yellow, or mushy leaves at the base indicate root rot from excess moisture.
• Soil: Well-draining cactus or succulent mix. Standard potting soil retains too much moisture. Add 30% perlite if using standard mix.
• Repotting: Every 2–3 years, or when roots circle the pot. Snake plants actually perform well when slightly rootbound.

For more on snake plant care specifics, see container gardening for small spaces for pot selection and positioning tips.

Pothos: easiest to keep alive

Pothos (Epipremnum aureum) removes benzene, formaldehyde, and xylene from indoor air and is the most forgiving air-purifying plant for beginners — it survives inconsistent watering, low light, and neglect better than any other option.

NASA tested pothos extensively and found it effective at removing formaldehyde at low concentrations particularly relevant to household product off-gassing. It’s also one of the fastest-growing houseplants, which means it produces more leaf surface area — the mechanism by which plants actually filter air — faster than slower-growing plants.

Care:

• Light: Grows in anything from near darkness to bright indirect light. In low light, the variegation fades to solid green — the plant survives but looks less interesting.
• Water: Let the top inch of soil dry between watering. In a typical US home in summer, that’s about weekly. In winter, every 10–14 days.
• Growing options: Trailing down a shelf, climbing a moss pole, or growing in water only (it roots and grows indefinitely in a glass vase). Growing in water is the ultimate low-maintenance setup — change the water weekly.

Propagation: Pothos propagates from stem cuttings in water in about 2 weeks. One 6-inch stem cutting dropped in a glass of water produces roots within 14 days. This makes it easy to multiply — start with one plant and have 8–10 cuttings distributed around the house within a year for broader air filtration.

Spider plant: best for pet households

Spider plant (Chlorophytum comosum) is non-toxic to cats and dogs, tolerates indirect light and variable watering, and removes formaldehyde and xylene from indoor air — making it the safest choice for US households with pets.

ASPCA confirms spider plant as non-toxic to both cats and dogs. It’s the top pick for any home where plants are within reach of animals. Mild hallucinogenic effects have been anecdotally reported in cats that chew the leaves, but no toxicity.

NASA’s testing found spider plant removed 95% of formaldehyde from a sealed chamber over 24 hours — one of the highest single-pollutant removal rates in the study.

Care:

• Light: Bright to medium indirect light. Tolerates low light but grows slowly and produces fewer “babies” (plantlets).
• Water: Weekly in summer, every 10–14 days in winter. More drought-tolerant than peace lily.
• Babies: Spider plants produce hanging plantlets called “spiders” on long stems. Pin a spider into a separate pot of moist soil or drop it in water to root. Free new plants in 3–4 weeks.
• Tip burn: Brown leaf tips are the most common issue. Caused by fluoride in tap water or low humidity. Use filtered water or let tap water sit overnight before using. Misting occasionally helps.

Bamboo palm and rubber plant: larger options

Bamboo palm (Chamaedorea seifrizii) removed the highest volumes of formaldehyde and benzene per plant in NASA’s study — because it’s large. More leaf surface area equals more filtration.

For a living room or open-plan US home where a 4–6-foot plant fits, bamboo palm is the highest-performing choice. It needs more light than snake plant or pothos (bright indirect, ideally near a south or east window) and more consistent watering. But for sheer filtration capacity, large plants outperform small ones because they have more leaf area.

Rubber plant (Ficus elastica) removes formaldehyde effectively and grows into a striking tree-form plant at 4–8 feet. It needs medium to bright indirect light and watering every 1–2 weeks when soil is nearly dry. Its large, glossy leaves have more surface area per plant than most small houseplants.

How many plants do you actually need?

The Drexel University 2019 analysis estimated 6–8 medium-to-large plants per 100 square feet for measurable air quality improvement in a room with normal air exchange.

For a 12×12-foot bedroom (144 square feet): 8–12 plants of medium size (6-inch pot and larger). This is more than most people keep, but achievable if you mix several plant types.

Practical approach for a US home:

• Prioritize rooms where you spend the most time: bedroom, home office, main living area
• Use larger plants where space allows — one 4-foot bamboo palm does more than four 4-inch snake plants
• Mix plants: one peace lily (broadest VOC spectrum), two snake plants (continuous night-time oxygen), and two pothos (fastest VOC removal per dollar) gives you a functional starting combination for a 120-square-foot room

The Drexel University analysis of NASA clean air data puts the scale requirement in clear terms for US home conditions.

Positioning and care for maximum filtration

Place air-purifying plants where VOCs are most concentrated: near new furniture, fresh paint, carpeting, and cleaning product storage areas.

VOC hotspots in US homes:

• New furniture and flooring: Formaldehyde and xylene off-gas most heavily in the first 6–12 months. A few plants near a new couch or freshly painted wall where air exchange is lower makes practical sense.
• Home office: Printers, electronics, and synthetic materials off-gas VOCs. Snake plants and pothos are the practical choices because they tolerate the lower light conditions common in offices.
• Kitchen: Cleaning products and cooking off-gas ammonia and other compounds. Peace lily is the best choice here if you have pets outside the kitchen.
• Bedroom: Snake plant’s nighttime oxygen conversion makes it the logical bedroom choice. Two medium snake plants in a typical US bedroom (150 square feet) represent a meaningful and practical setup.

For guidance on how to start composting and using organic matter to support healthy indoor potting mixes, or on how to start a garden if you’re ready to expand from indoor to outdoor plants.

Common problems with air-purifying plants

Yellowing leaves on peace lily or snake plant almost always mean overwatering. Let the soil dry more between waterings. For peace lily, the soil should be barely moist; for snake plant, completely dry to 2 inches depth.

Brown leaf tips on spider plants or peace lily typically indicate fluoride toxicity or low humidity. Switch to filtered or rain water. A humidity tray under the pot helps in dry US climates (Denver, Phoenix, any zone with low winter indoor humidity).

Leggy, pale pothos means insufficient light. Move closer to a window or add a grow light. Pothos tolerates low light but doesn’t thrive in it — leaves become smaller and more widely spaced.

Scale insects attack rubber plants and dracaena most commonly. They appear as small brown bumps on stems. Wipe with a cotton ball dipped in 70% isopropyl alcohol, or spray with insecticidal soap. Repeat every 7 days for 3–4 treatments.

Root rot from overwatering is the top killer of all houseplants. Prevention: use pots with drainage holes (always), allow appropriate drying time between waterings, and use well-draining potting mix. If root rot is suspected, unpot the plant, cut away all brown or mushy roots, dust with sulfur or cinnamon (antifungal), and repot in fresh dry mix. See how to get rid of gnats in plants — fungus gnats indicate consistently wet soil, which leads to root rot.