Do indoor plants really purify air?

While plants can remove some pollutants in controlled experiments, research suggests their impact on air quality in typical homes is often minimal due to the scale needed to make a noticeable difference.

How many plants do I need to actually purify the air in my home?

Studies suggest you'd need a very high density of plants – potentially hundreds or even thousands per square meter – to achieve significant air purification, far exceeding what's practical for most homes.

What factors affect how well plants can purify air?

A plant's efficiency is influenced by factors like the specific pollutants present, the plant species, the size and surface area of its leaves, light exposure, humidity, and the activity of microorganisms in the soil.

If plants aren't enough, what are some practical alternatives for improving indoor air quality?

Effective alternatives include using air purifiers with HEPA filters, ensuring adequate ventilation by opening windows, reducing sources of indoor pollution (like VOC-containing cleaning products), and regularly cleaning to reduce dust and allergens.

Are there any plants that are better than others at purifying air?

NASA research indicates some plants like spider plants, snake plants, peace lilies, and English ivy may be more effective at removing certain pollutants like formaldehyde, xylene, and toluene, though the overall impact in a real-world setting may still be limited.

Indoor Plant Truth: Air Quality?

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

indoor plantsair qualityhome improvementhealthgardeningplants

Are you looking to improve the air quality in your home? Maybe you've heard that indoor plants are a natural way to purify the air and rid your home of harmful toxins. The idea of turning your living space into a lush, green oasis while simultaneously breathing cleaner air is definitely appealing. But does this claim really hold up under scientific scrutiny? Let's dig into the truth about indoor plants and their impact on air quality.

The NASA Clean Air Study: A Seed of an Idea

In 1989, NASA, in collaboration with the Associated Landscape Contractors of America (ALCA), published the NASA Clean Air Study. This research explored the potential of houseplants to remove volatile organic compounds (VOCs) from the air in sealed environments. VOCs, such as formaldehyde, benzene, xylene, and trichloroethylene, are emitted by common household items like furniture, paints, cleaning products, and even clothing. Exposure to these chemicals can cause a range of health issues, from headaches and eye irritation to more serious long-term effects.

The NASA study identified several plants that were particularly effective at removing specific VOCs. Some of the top performers included:

Snake Plant (Sansevieria trifasciata): Excellent at removing formaldehyde, xylene, toluene, and nitrogen oxides.
Spider Plant (Chlorophytum comosum): Effective against formaldehyde, xylene, and carbon monoxide.
Peace Lily (Spathiphyllum wallisii): Removes formaldehyde, benzene, trichloroethylene, xylene, toluene, and ammonia.
English Ivy (Hedera helix): Good at absorbing formaldehyde, benzene, xylene, toluene, and trichloroethylene.
Golden Pothos (Epipremnum aureum): Effective against formaldehyde, xylene, and benzene.

The results of the NASA study sparked widespread interest in using houseplants as a natural way to improve indoor air quality. The image of a few strategically placed plants transforming a stuffy room into a haven of fresh air quickly took root in popular culture. But let's examine a more complete picture of the science behind this idea.

Beyond the Lab: Real-World Considerations

While the NASA Clean Air Study provided valuable insights, it's important to consider the limitations of the research and how the findings translate to real-world conditions. The study was conducted in small, sealed chambers, which are very different from the typical home or office environment. The air exchange rates, the concentration of VOCs, and the number of plants used were carefully controlled in the laboratory setting.

In a typical home, the air is constantly being exchanged with the outside environment through ventilation systems, open windows and doors, and even small cracks and gaps in the building's structure. This means that the concentration of VOCs in the air is constantly fluctuating, and the ability of a few houseplants to make a significant impact is greatly reduced.

Research suggests that to achieve the same level of air purification observed in the NASA study, you would need a staggering number of plants – potentially hundreds – in a typical-sized room. A study by Purdue University, for example, indicated that you would need about 10 plants per square foot of floor space to achieve a noticeable effect on air quality, effectively turning your home into a jungle. While this may appeal to some plant enthusiasts, it's hardly a practical solution for most people.

Factors Affecting Plant Effectiveness

Even if you were to fill your home with a large number of plants, several factors can influence their effectiveness in removing VOCs:

Plant Species and Variety

As the NASA study showed, different plant species have varying abilities to remove specific VOCs. Some plants are more effective at removing formaldehyde, while others excel at absorbing benzene or xylene. Choosing the right plants for the specific VOCs present in your home is crucial.

Plant Size and Health

Larger, healthier plants are generally more effective at removing VOCs than smaller, less vigorous plants. A plant's ability to absorb pollutants is directly related to its surface area and its overall health. Ensure your plants are well-cared for and receive adequate light, water, and nutrients to maximize their air-purifying potential.

Soil Microorganisms

The soil in which plants grow also plays a role in air purification. Microorganisms in the soil can break down VOCs, further contributing to the removal of pollutants from the air. The type and abundance of these microorganisms can vary depending on the soil composition and moisture levels. Using high-quality potting mix and maintaining proper soil moisture can help promote the growth of beneficial microorganisms.

Airflow

Airflow is also an important factor. Plants need to be exposed to the air containing VOCs to effectively absorb and process them. If plants are placed in areas with poor airflow, their ability to purify the air will be limited. Consider using fans or opening windows to improve air circulation around your plants.

Other Benefits of Indoor Plants

While the air-purifying capabilities of houseplants may be overstated, they do offer a range of other benefits that can enhance your living environment and well-being:

Increased Humidity: Plants release moisture into the air through transpiration, which can help increase humidity levels, especially during dry winter months. This can alleviate dry skin, soothe irritated sinuses, and reduce the risk of respiratory infections.
Reduced Stress and Improved Mood: Studies have shown that being around plants can lower stress levels, improve mood, and boost creativity. The presence of plants in your home or office can create a more calming and relaxing atmosphere.
Aesthetic Appeal: Plants add beauty and visual interest to any space. They can soften harsh lines, bring a touch of nature indoors, and create a more inviting and welcoming environment.
Noise Reduction: Plants can absorb and deflect sound waves, helping to reduce noise levels in your home or office. This can be particularly beneficial in urban areas or noisy environments.

Practical Tips for Improving Indoor Air Quality

While relying solely on houseplants for air purification may not be the most effective strategy, there are several other steps you can take to improve the air quality in your home:

Ventilate Regularly: Open windows and doors to allow fresh air to circulate. Even a few minutes of ventilation each day can significantly reduce the concentration of VOCs and other pollutants.
Use Air Purifiers: Consider using an air purifier with a HEPA filter to remove particulate matter, allergens, and other pollutants from the air. Look for models that also have activated carbon filters to absorb VOCs.
Choose Low-VOC Products: When purchasing furniture, paints, cleaning products, and other household items, opt for low-VOC or VOC-free options. These products release fewer harmful chemicals into the air.
Control Humidity: Maintain proper humidity levels in your home to prevent the growth of mold and mildew, which can release spores and other allergens into the air. Use a humidifier or dehumidifier as needed.
Clean Regularly: Dust and vacuum regularly to remove allergens and particulate matter from your home. Pay attention to areas where dust tends to accumulate, such as carpets, rugs, and upholstered furniture.
Avoid Smoking Indoors: Smoking indoors releases a cocktail of harmful chemicals into the air, which can significantly degrade air quality and pose serious health risks.

Conclusion: A Breath of Fresh Air

While indoor plants may not be the miracle air purifiers we once thought them to be, they still offer a multitude of benefits that can enhance our living spaces and improve our well-being. Their ability to remove VOCs from the air is limited in real-world conditions, but their other positive attributes, such as increasing humidity, reducing stress, and adding aesthetic appeal, make them a valuable addition to any home or office. Don't hesitate to embrace the joys of indoor gardening. Just recognize that achieving optimal air quality requires a multifaceted approach, combining the charm of plants with other proven methods like ventilation, air purifiers, and the use of low-VOC products.

Next Steps:

Research the best air purifier for your specific needs and budget.
Identify potential sources of VOCs in your home and take steps to reduce their emissions.
Experiment with different plant varieties and arrangements to create a visually appealing and healthy indoor environment.