NASA Clean Air Study: 10 Best Air-Purifying Plants for Your Home

What Is the NASA Clean Air Study?

In 1989, NASA and the Associated Landscape Contractors of America tested common houseplants in sealed chambers to see how effectively they removed volatile organic compounds (VOCs) — formaldehyde, benzene, trichloroethylene, and others — from the air. The goal was originally to find ways to filter air in sealed space habitats, but the results became one of the most cited (and most oversimplified) pieces of houseplant research ever published.

The honest caveat: the study measured air removal in small, sealed lab chambers over 24 hours per plant. A single houseplant in an average-sized, normally-ventilated room will not measurably change your air quality on its own — you would need an impractical number of plants per square foot to match the lab conditions. That said, the plants below genuinely do process VOCs at the leaf and root level, they are excellent low-maintenance houseplants regardless, and a cluster of several in a room is a reasonable, low-effort complement to normal ventilation.

Quick Comparison

1. Boston Fern (Nephrolepis exaltata)

One of the top performers in the NASA study for removing formaldehyde. Boston ferns also add humidity to a room through transpiration, making them a natural fit for bathrooms and kitchens. See our complete Boston fern growing guide for humidity and misting details.

2. ZZ Plant (Zamioculcas zamiifolia)

Documented for removing xylene and toluene, and famously tolerant of low light and irregular watering — genuinely one of the hardest houseplants to kill. Read the ZZ plant beginner's guide for care basics.

3. Chinese Evergreen (Aglaonema)

Excellent formaldehyde and benzene removal in the original study, and one of the most forgiving low-light houseplants available. Full details in the Chinese evergreen growing guide.

4. Dracaena (multiple species)

Several Dracaena species were tested and performed well against benzene, formaldehyde, and trichloroethylene. Varieties range from the spiky Dragon Tree to the lush Corn Plant. See the Dracaena growing guide for variety-specific care.

5. Spider Plant (Chlorophytum comosum)

A classic NASA-study performer for formaldehyde and carbon monoxide, and one of the easiest plants to propagate — it produces "babies" you can root in water. The spider plant guide covers propagation step by step.

6. Snake Plant (Sansevieria trifasciata)

Notable for continuing to release oxygen at night (unlike most plants, which switch to carbon dioxide release after dark), making it a popular bedroom pick. Removes formaldehyde and benzene. See the snake plant growing guide.

7. Monstera (Monstera deliciosa)

Not part of the original 1989 NASA list but included in later air-quality research for VOC uptake, and one of the most popular statement houseplants today. Full care in the Monstera growing guide.

8. Peace Lily (Spathiphyllum)

Ranked among the most effective plants in the NASA study for removing benzene, formaldehyde, and ammonia, and one of the few flowering plants that tolerates low light. Note: toxic to pets if chewed. See the peace lily growing guide.

9. Rubber Plant (Ficus elastica)

Broad, glossy leaves with a large surface area for VOC absorption, and a fast-growing option for filling a living-room corner. Details in the rubber plant growing guide.

10. Pothos (Epipremnum aureum)

Not part of the original NASA list but one of the most-studied houseplants since for formaldehyde removal, and the easiest plant on this entire list to keep alive. Start with the pothos growing guide.

How Many Plants Do You Actually Need?

The lab conditions behind the NASA study are not realistic for a home. As a practical guideline: aim for one plant per 100 square feet as a reasonable, low-effort addition to normal ventilation — not a replacement for opening windows or using an air purifier for a real air-quality problem (smoke, mold, high VOC off-gassing from new furniture).

FAQ

Do air-purifying plants actually work?

Partially, and the effect is smaller than popular articles suggest. The NASA study measured VOC removal in sealed chambers, not ventilated rooms. The plants above do process some airborne toxins, but you would need dozens per room to match the lab's air-to-plant ratio. Think of them as a genuine, minor contributor alongside — not instead of — normal ventilation.

Which plant purifies the air the best?

Peace lily, Chinese evergreen, and Boston fern consistently rank at the top of published lab studies for VOC removal, but the difference between the top and bottom of this list is smaller in a real room than the lab numbers suggest.

Are air-purifying plants safe for pets?

Not all of them. Peace lily, pothos, and Chinese evergreen are toxic to cats and dogs if chewed. Spider plant, Boston fern, and areca palm are pet-safe alternatives if you have curious animals — see our pet-safe houseplants guide for a full list.

Can houseplants replace an air purifier?

No. For a real air-quality problem — wildfire smoke, mold, high formaldehyde off-gassing from new furniture or flooring — an actual HEPA air purifier is far more effective per square foot than any number of houseplants. Plants are a low-effort complement, not a substitute.