What was the NASA Clean Air Study?

The NASA Clean Air Study was a project in 1989 that researched methods to purify air in sealed environments, like space stations. It investigated the ability of certain plants to remove volatile organic compounds (VOCs) from the air.

Did the NASA Clean Air Study prove that houseplants effectively purify air in homes?

While the NASA study showed plants could remove VOCs in sealed chambers, more recent research suggests that houseplants don't purify air effectively in real-world home conditions. You would need an impractical number of plants to achieve a noticeable effect, and ventilation systems in buildings remove VOCs more effectively.

Which plants were tested in the NASA Clean Air Study?

The NASA Clean Air Study tested a variety of common houseplants, including the Variegated snake plant, English ivy, Peace lily, Chinese evergreen, Bamboo palm, Red-edged dracaena, Cornstalk dracaena, Weeping fig, Barberton daisy, Florist's chrysanthemum, and Janet Craig.

Are there any benefits to having houseplants if they don't significantly purify the air?

Yes, houseplants can still offer benefits! They can improve the aesthetic appeal of a space, potentially reduce stress, and may help to regulate humidity. Some studies also suggest plants can reduce bacteria and mold spores in their immediate surroundings.

Is the claim that snake plants can generate enough oxygen for a single human's survival true?

No, this claim, which went viral in 2023, is false. There is no evidence in the NASA report or elsewhere to support the idea that a few snake plants can generate enough oxygen for a person's survival.

NASA Plant Study: Fact vs. Myth

By Home Sidekick Team May 24, 2025 7 min read 1314 words

NASAClean Air StudyPlantsAir PurificationMythsHomeGarden

Indoor plants are often touted as natural air purifiers, capable of transforming our homes and offices into havens of fresh, clean air. This belief is largely fueled by the famous NASA Clean Air Study, conducted in 1989. But how much of what we know about the air-purifying power of houseplants is fact, and how much is myth? Let's delve into the details of the NASA study, separate the scientific findings from popular misconceptions, and explore practical ways to improve indoor air quality with plants.

The NASA Clean Air Study: Unveiling the Truth

The NASA Clean Air Study, officially titled "Interior Landscape Plants for Indoor Air Pollution Abatement," was a collaborative effort between NASA and the Associated Landscape Contractors of America (ALCA). The primary goal was to identify plants that could remove volatile organic compounds (VOCs) from the air in sealed environments, specifically for use in space stations. VOCs are emitted from common household items like paints, furniture, and cleaning products, and can contribute to "sick building syndrome," causing symptoms like headaches, fatigue, and respiratory irritation. (Wolverton, B. C., et al., 1989)

Key Findings of the NASA Study

Plant Effectiveness: The study identified several houseplants that effectively removed specific VOCs from the air. Notable examples included the Peace Lily (Spathiphyllum), Snake Plant (Sansevieria trifasciata), and Golden Pothos (Epipremnum aureum).
VOC Removal: The plants demonstrated the ability to remove chemicals like formaldehyde, benzene, trichloroethylene, xylene, and toluene.
Sealed Chamber Environment: It's crucial to note that the research was conducted in small, sealed chambers. Plants were placed in these chambers with specific VOCs, and the air was analyzed over time to measure the reduction in pollutant levels.

These findings were groundbreaking and ignited public interest in the air-purifying potential of houseplants. However, the context of the study is essential for understanding the true impact of plants on indoor air quality in real-world settings.

Myth vs. Reality: Separating Fact from Fiction

While the NASA study provided valuable insights, it's crucial to understand the limitations and how its findings translate to our homes and offices. The biggest misconception is that a few houseplants can dramatically improve air quality in a typical indoor environment. Let's break down the key myths and realities:

Myth 1: A Few Plants Can Purify an Entire Room

Reality: The NASA study was conducted in highly controlled, sealed environments. The air volume in these chambers was significantly smaller than in a typical room. To achieve comparable air purification in a home or office, you would need a staggering number of plants – far more than most people could reasonably accommodate. One study estimates that you would need approximately 10 plants per square foot of floor space to achieve the same air purification levels as in the NASA experiments. (Ohio State University Extension, 2024) That's more of a jungle than a living room!

Myth 2: Plants are the Only Solution for Indoor Air Pollution

Reality: Plants can contribute to improved air quality, but they are not a substitute for proper ventilation and other measures. Opening windows regularly, using air purifiers with HEPA filters, and avoiding sources of VOCs are all essential steps in creating a healthy indoor environment. Plants should be considered part of a holistic approach, not a standalone solution.

Myth 3: All Plants are Equally Effective at Air Purification

Reality: The NASA study highlighted specific plants that were particularly effective at removing certain VOCs. While most plants contribute to air quality by absorbing carbon dioxide and releasing oxygen, their ability to remove VOCs varies significantly. Choose plants known for their air-purifying properties to maximize their impact.

Top Air-Purifying Plants (According to Research)

Based on the NASA Clean Air Study and subsequent research, here are some of the most effective air-purifying plants:

Snake Plant (Sansevieria trifasciata): Also known as Mother-in-Law's Tongue, this plant is incredibly low-maintenance and effective at removing formaldehyde, xylene, toluene, and nitrogen oxides. It also converts carbon dioxide to oxygen at night, making it a great addition to bedrooms.
Peace Lily (Spathiphyllum): This elegant plant is excellent at removing formaldehyde, benzene, trichloroethylene, xylene, and ammonia. It thrives in shade and requires moist soil. Note that Peace Lilies are toxic to pets, so keep them out of reach.
Golden Pothos (Epipremnum aureum): One of the easiest houseplants to grow, the Golden Pothos is highly effective at removing formaldehyde, xylene, and toluene. It can be grown in hanging baskets or trained to climb. Like Peace Lilies, it is toxic to pets.
Spider Plant (Chlorophytum comosum): This plant is easy to propagate and effective at removing formaldehyde and xylene. It is also safe for pets.
English Ivy (Hedera helix): While it can be invasive outdoors, English Ivy is an excellent indoor air purifier, particularly for removing mold and formaldehyde. It prefers cooler temperatures and bright, indirect light. Toxic to pets.
Aloe Vera (Aloe barbadensis miller): Besides its air-purifying qualities (particularly formaldehyde), Aloe Vera is also a useful plant to have on hand for treating minor burns and cuts.
Chinese Evergreen (Aglaonema): This low-maintenance plant is effective at removing formaldehyde, benzene, and other toxins.

Optimizing Plant Power: Practical Tips for Cleaner Air

To maximize the air-purifying benefits of houseplants, consider these practical tips:

Choose the Right Plants: Focus on plants that have been scientifically proven to remove VOCs, as listed above.
Increase Plant Density: While you don't need a jungle, having several plants in a room will be more effective than just one or two. Aim for a variety of plants to target a wider range of pollutants.
Maintain Plant Health: Healthy plants are more effective at air purification. Provide adequate light, water, and nutrients to keep your plants thriving.
Clean Plant Leaves: Dust can accumulate on plant leaves, hindering their ability to absorb pollutants. Wipe the leaves regularly with a damp cloth.
Consider Soil Microbes: The NASA study found that microorganisms in the soil also play a role in air purification. Ensure proper soil drainage to prevent the growth of harmful bacteria.
Supplement with Other Air Purification Methods: Use plants in conjunction with air purifiers, proper ventilation, and strategies to reduce VOC sources.

Beyond Air Purification: Additional Benefits of Houseplants

Even if their air-purifying abilities are somewhat overstated, houseplants offer numerous other benefits that make them a worthwhile addition to any home or office:

Improved Mood and Reduced Stress: Studies have shown that being around plants can reduce stress, improve mood, and increase feelings of well-being. (Ulrich, R. S., 1984)
Increased Productivity and Focus: Plants can create a more calming and productive work environment.
Aesthetic Appeal: Plants add beauty and visual interest to any space, making it more inviting and enjoyable.
Humidity Regulation: Plants release water vapor into the air, which can help to increase humidity levels, especially during dry winter months.

Conclusion: Embracing a Holistic Approach to Indoor Air Quality

The NASA Clean Air Study was a valuable piece of research that sparked interest in the air-purifying potential of houseplants. While the study's findings may not directly translate to the real-world environment without a significant number of plants, houseplants can still play a role in creating a healthier and more pleasant indoor space. By understanding the science behind air purification, choosing the right plants, and supplementing with other air quality measures, you can create a home or office that is both beautiful and beneficial to your well-being.

Next Steps:

Assess the air quality in your home or office by identifying potential sources of VOCs.
Choose a selection of air-purifying plants based on your needs and preferences.
Implement other air purification strategies, such as using air purifiers and improving ventilation.
Monitor your indoor air quality and make adjustments as needed.

References

Wolverton, B. C., Johnson, A., & Bounds, K. (1989). Interior landscape plants for indoor air pollution abatement. NASA.
Ohio State University Extension. (2024). Houseplants and indoor air pollution. https://ohioline.osu.edu/factsheet/HYG-1430
Ulrich, R. S. (1984). View through a window may influence recovery from surgery. Science, 224(4647), 420-421.