The idea that houseplants can purify indoor air has led to a significant increase in indoor gardening. Indoor air pollution is often caused by Volatile Organic Compounds (VOCs), which are gases emitted from household materials like paints, cleaning supplies, furniture, and building materials. Certain plants have demonstrated a capacity to absorb and neutralize these VOCs. This article explores the scientific process behind this air cleaning and identifies the most effective plants.
How Plants Interact with Indoor Air Toxins
The mechanism by which plants clean the air is called phytoremediation. Plants absorb airborne pollutants through their leaves, primarily via the stomata (small pores used for gas exchange), and transfer them down to their root systems.
The plant itself is not the sole agent of purification; the soil is the most active part of the system. The potting mix contains a complex community of microorganisms, including bacteria and fungi, which thrive around the roots. These microbes use the absorbed VOCs as a food source, breaking the toxic compounds down into harmless substances such as carbon dioxide and water.
This microbial degradation permanently removes gaseous pollutants from the air. The combined action of the plant’s foliage and the root-zone microbes creates a biofiltration system that continuously processes airborne contaminants.
Specific High-Performing Air-Purifying Plants
Certain species are known for their superior ability to process indoor air pollutants.
Peace Lily (Spathiphyllum)
The Peace Lily is recognized for processing a wide range of toxins. It is effective against formaldehyde, benzene, and trichloroethylene, which are common chemicals found in glues, plastics, and synthetic fabrics. Peace Lilies can also remove ammonia, a substance often found in cleaning products.
Snake Plant (Sansevieria trifasciata)
Also known as Mother-in-Law’s Tongue, the Snake Plant is a top performer against VOCs. This resilient plant absorbs benzene, formaldehyde, xylene, and trichloroethylene. Snake plants are tolerant of low light conditions and require minimal watering, making them appealing for many homes.
Spider Plant (Chlorophytum comosum)
The Spider Plant is a popular houseplant that demonstrates air-cleaning properties. Studies indicate it is efficient at removing formaldehyde, a pollutant off-gassed from pressed wood products. It also shows efficacy against benzene and toluene.
Understanding Real-World Effectiveness and Limitations
The popular understanding of plants as powerful air purifiers stems from the 1989 NASA Clean Air Study. This research demonstrated that common houseplants could effectively remove VOCs like formaldehyde and benzene from the air. The study’s purpose was to develop a natural air regeneration system for sealed environments, such as future space stations.
The study’s success took place under highly controlled and unventilated conditions. Plants were placed in small, sealed chambers (approximately 0.9 cubic meters) with no air exchange. This specialized environment is not comparable to a typical home or office, which has fluctuating airflow and ventilation.
In a standard residential setting, the natural air exchange rate of a building is usually the dominant factor in pollutant removal. To match the air purification rate of a typical ventilation system, the number of plants required would be impractical. Some analyses estimate that 10 to 1,000 plants per square meter of floor space would be needed to match the efficiency observed in the sealed chambers.
While plants are scientifically proven to process VOCs, their practical impact on air quality in a standard home is minimal compared to mechanical air filtration systems. The value of these plants lies in their ability to process pollutants in a closed system, which remains an area of active research for engineered biofiltration technologies.