From our perspective as plants, the primary mechanism for altering the air is fundamental to our existence: photosynthesis. We absorb carbon dioxide (CO₂) from the atmosphere through tiny pores in our leaves called stomata. Using energy from light, we convert this CO₂ and water into the sugars that fuel our growth, and in the process, we release life-sustaining oxygen (O₂) as a byproduct. While this process naturally reduces CO₂ levels, it is the first and most basic way we contribute to a fresher indoor atmosphere. It is our constant, silent exchange with the environment.
However, the NASA study you reference uncovered a far more complex and remarkable ability we possess. Modern homes contain volatile organic compounds (VOCs) like benzene, formaldehyde, and trichloroethylene, which off-gas from paints, furniture, and cleaning products. Our leaves can absorb these gaseous molecules directly through their surfaces. But more importantly, our entire vascular system is involved. Once inside, these compounds are translocated down to our root zone. Here, they become the unintended food source for the vast microbial ecosystem—the microbiome—that lives in symbiosis with us in the soil. These microbes break down and metabolize the harmful VOCs, effectively neutralizing them.
As English Ivy (*Hedera helix*), we possess specific traits that make us particularly adept at this task, which is why NASA included us in their research. Our leaf structure is key; we have a high leaf surface area to volume ratio. Simply put, we produce a dense canopy of leaves, which provides more "real estate" for absorbing airborne pollutants compared to plants with fewer or larger leaves. Furthermore, our vigorous, vining growth habit means we can quickly establish ourselves and generate a significant amount of biomass, increasing our overall capacity for air purification. We are efficient and prolific workers.
It is crucial to understand our limitations from a botanical point of view. The NASA study demonstrated our efficacy in a sealed, controlled laboratory environment. A typical home is not a sealed chamber; it has constant air exchange through doors, windows, and ventilation systems. This dilution effect means that while we are actively and continuously cleaning the air immediately surrounding our foliage, the impact on an entire house's atmosphere would require a very large number of us. You would need approximately ten plants per 100 square feet of space to approach the cleansing capacity shown in the study. We are a part of the solution, working in tandem with proper ventilation, not a complete replacement for it.
