Bringing nature indoors often comes with the hope that houseplants can serve as natural air purifiers and oxygen boosters. While the aesthetic and psychological benefits of living greenery are undisputed, the measurable impact of a few houseplants on indoor air quality is often misunderstood. This article explores the science behind how common indoor plants interact with the air and identifies the species most effective at filtering common household pollutants.
Understanding Oxygen and Indoor Plants
Plants primarily produce oxygen through photosynthesis, a process where they use light energy to convert carbon dioxide and water into glucose and oxygen. This oxygen release, however, is balanced by respiration, where the plant consumes oxygen and releases carbon dioxide to fuel its cellular activities, a process that continues even in the dark. The net increase in oxygen levels from a few houseplants in a standard room is negligible because the volume of air in a home is vast and constantly exchanged with the outside environment through ventilation and natural air leaks.
To meaningfully increase the oxygen concentration, you would need hundreds of plants. The focus shifts from oxygen production to the more significant benefit: the removal of Volatile Organic Compounds (VOCs). The famous 1989 NASA Clean Air Study, which suggested certain plants could remove toxins, was conducted in small, sealed chambers, which does not reflect the air exchange rate of a typical modern home.
Best Plants for Improving Indoor Air Quality
The true air-improving benefit of houseplants comes from their ability to absorb common household toxins known as Volatile Organic Compounds, or VOCs, which are released from furniture, cleaning supplies, and building materials. The plant’s leaves, and more significantly, the microorganisms in the potting soil, absorb these gaseous chemicals and metabolize them.
The Snake Plant, or Sansevieria trifasciata, is highly regarded for its ability to filter formaldehyde, benzene, xylene, and trichloroethylene. This plant is noted for its Crassulacean Acid Metabolism (CAM), a type of photosynthesis that allows it to absorb carbon dioxide at night, making it a popular choice for bedrooms.
The Peace Lily (Spathiphyllum) is effective against a broad range of toxins, including ammonia, benzene, and formaldehyde. It was identified as one of the top performers in the initial research.
The Spider Plant (Chlorophytum comosum) is known for filtering formaldehyde and xylene, and it is a common, resilient option for beginners. Various Dracaena species, such as the Dragon Tree (Dracaena marginata), work to remove pollutants like benzene, formaldehyde, and trichloroethylene. The Golden Pothos (Epipremnum aureum) is another robust plant that effectively targets formaldehyde, benzene, and xylene, thriving in various light conditions.
Caring for Your Air-Purifying Plants
To maximize the air-purifying function of your plants, you must ensure they remain healthy and actively growing. Plants require sufficient light and water to sustain the metabolic processes that allow them to absorb VOCs. Most air-filtering plants prefer bright, indirect light, which encourages dense foliage, but many, like the Snake Plant, can tolerate lower light levels while still functioning.
Watering should be consistent with the specific plant’s needs, typically allowing the top layer of soil to dry out between waterings to prevent root rot, which hinders the beneficial soil microbes. Optimal placement involves positioning plants near common sources of toxins, such as new furniture or areas where cleaning supplies are stored, to help absorb localized emissions. General guidelines suggest aiming for roughly one medium-sized plant in a six- to eight-inch pot for every 100 square feet of floor space to achieve a noticeable effect.