How do house plants actually purify the air?

How do house plants actually purify the air?

Houseplants are like little magicians, quietly working their wonders in the background. They don't just add a pop of green to your decor; they perform the extraordinary feat of transforming polluted indoor air into fresh, breathable bliss. But how exactly do these green alchemists achieve this? Let’s explore the fascinating science behind how plants purify the air.

The Basics of Photosynthesis: Nature’s Air Filter

At the heart of a plant’s air-purifying ability lies the magical process of photosynthesis. Think of photosynthesis as a plant’s way of breathing. During this process, plants absorb carbon dioxide (CO₂) from the air and, with the help of sunlight and water, convert it into oxygen (O₂) and glucose. This not only supplies us with the oxygen we breathe but also reduces the amount of CO₂, a common indoor pollutant.

Stomata: Tiny Doorways to Clean Air

Plants have microscopic pores on their leaves called stomata, which open and close to regulate gas exchange. These tiny doorways allow plants to inhale CO₂ and exhale O₂. But that’s not all – they also act as gateways for other air pollutants, pulling them into the plant's system for a thorough clean-up.

Absorbing and Breaking Down VOCs

Volatile organic compounds (VOCs) are nasty chemicals found in many household products like paints, cleaning supplies, and furniture. VOCs can wreak havoc on indoor air quality and pose health risks. Fortunately, plants are natural VOC busters. They absorb these harmful compounds through their stomata and sometimes through their roots. Once inside, the magic happens.

Studies have shown that certain houseplants can significantly reduce levels of VOCs such as formaldehyde, benzene, and trichloroethylene. The absorbed VOCs are either stored in the plant’s tissues or metabolized into less harmful substances.

The Rhizosphere: Underground Allies

Below the surface, the plant roots are not working alone. They interact with a vibrant community of microorganisms in a region known as the rhizosphere. These underground allies, including bacteria and fungi, play a crucial role in the breakdown of pollutants. When a plant absorbs VOCs, these pollutants are transported to the roots, where soil microorganisms step in to degrade them into harmless byproducts. This symbiotic relationship enhances the plant's air-purifying power.

The Science of VOC Breakdown

The process of breaking down VOCs into safer compounds involves several fascinating steps:

  1. Absorption: VOCs enter the plant through the stomata on the leaves. Once inside, they travel through the plant’s vascular system to various tissues, including the roots.

  2. Translocation: The absorbed VOCs are transported to the roots, where the real magic begins.

  3. Microbial Degradation: Soil microorganisms in the rhizosphere use enzymes to break down VOCs. For example:

    • Formaldehyde is converted into formic acid and eventually into carbon dioxide and water.
    • Benzene is broken down into phenol, which is further metabolized into simpler compounds.
    • Trichloroethylene (TCE) is transformed into chloride ions, water, and carbon dioxide.
  4. Plant Metabolism: Some VOCs are directly metabolized by the plant. Through metabolic processes involving oxidation, reduction, and conjugation, plants transform these harmful compounds into non-toxic metabolites.

Boosting Airflow for Maximum Filtration

To enhance the air-purifying efficiency of plants, optimal airflow around the roots and leaves is essential. This is why planter designs that promote better aeration are so effective. Increased airflow allows plants to absorb more pollutants and supports the microorganisms in the rhizosphere, ensuring continuous and efficient filtration.

Super Plants: Nature’s Top Performers

Not all plants are created equal when it comes to air purification. Some species are particularly adept at filtering specific pollutants. For instance, spider plants (Chlorophytum comosum) excel at removing formaldehyde, while peace lilies (Spathiphyllum) are champions at filtering out benzene and trichloroethylene.

NASA’s Clean Air Study identified several superstar houseplants for air purification, including:

  • English Ivy (Hedera helix)
  • Snake Plant (Sansevieria trifasciata)
  • Aloe Vera (Aloe barbadensis)
  • Boston Fern (Nephrolepis exaltata)
  • Areca Palm (Dypsis lutescens)

More Than Just Air Purification

The benefits of houseplants go beyond just cleaning the air. They also help regulate humidity levels, which can prevent various health issues and inhibit the growth of mold and dust mites. Additionally, the presence of plants has been shown to improve mental well-being, reduce stress, and boost productivity.


Houseplants are not just pretty decorations; they are vital components of a healthy indoor environment. Through photosynthesis, absorption of VOCs, and the symbiotic relationships in the rhizosphere, plants naturally filter the air, making our homes cleaner and healthier. Integrating plants into our living spaces is one of the simplest and most effective ways to enhance our well-being.

By understanding the science behind how plants filter the air, we can better appreciate these green guardians and make informed choices about incorporating them into our homes. This intricate balance of biology and ecology not only beautifies our living spaces but also fosters a healthier and more sustainable environment.