As a plant, our primary interaction with the air is through tiny pores on the undersides of our leaves, called stomata. These are the gateways for the essential processes of photosynthesis and respiration. We open our stomata to take in carbon dioxide (CO2) and, in a process known as transpiration, release water vapor and oxygen back into the atmosphere. This constant gas exchange is the fundamental engine of air purification. When volatile organic compounds (VOCs) like benzene, formaldehyde, or trichloroethylene are present in the air, they can be absorbed into our leaf tissues through these same stomatal openings along with the CO2.
The story continues below the soil line. Our root system does not work in isolation; it forms a symbiotic relationship with a vast community of microorganisms in the rhizosphere—the zone of soil surrounding our roots. The 1989 NASA Clean Air Study, which brought us Peace Lilies (Spathiphyllum) into the spotlight, highlighted a crucial fact: the potted plant's system is a holistic air filtration unit. The VOCs absorbed through our leaves are transported down to our roots. Here, they serve as a food source for the beneficial microbes that live in symbiosis with us. These microbes break down the harmful chemicals into harmless byproducts, which we can then use as nutrients. Therefore, the purification process is a partnership between our plant tissues and our root microbiome.
From our perspective, the NASA study demonstrated our proven capability to remove trace levels of VOCs from a sealed, controlled laboratory environment. In such conditions, with contaminants introduced at specific concentrations, we performed remarkably well. However, the environment inside a typical home or office is vastly different. It is not a sealed chamber; doors open, windows open, and outdoor air exchanges with indoor air constantly. The scale of purification required is also immense. To replicate the air-cleaning effect observed in the NASA study in a large living space, you would need a very high density of our foliage—potentially covering a significant portion of the room's floor space.
It is also vital to understand what we, as plants, cannot do. We are not designed to be the primary solution for particulate matter like dust, allergens, or smoke. These are physical particles that may settle on our broad leaves (and can be wiped off), but they are not processed through our stomata and root systems. Furthermore, our photosynthetic process, which absorbs CO2 and releases oxygen, occurs only during daylight hours. At night, we respire like animals, taking in oxygen and releasing CO2, though the net effect on oxygen in a room is negligible. Placing a great number of us in a small, completely sealed bedroom is therefore not advisable from an air quality perspective.
