The Pachira aquatica, commonly known as the Money Tree, is a popular houseplant often recognized by its signature braided trunk and glossy, palmate leaves. This tropical tree has become widely associated with good fortune and prosperity, making it a frequent housewarming gift. Beyond its symbolic meaning, the Money Tree is frequently marketed as a natural air purifier, capable of cleansing the air inside homes. This claim suggests that the plant actively removes harmful compounds from indoor environments, contributing to a healthier living space.
The Mechanism of Plant Air Filtration
The biological ability of plants to remove airborne contaminants is a process called phytoremediation, a natural system shared by nearly all flora. This mechanism involves two main steps for the removal of gaseous pollutants, known as Volatile Organic Compounds (VOCs). The first step occurs when a plant’s leaves absorb these gaseous chemicals from the surrounding air through tiny pores called stomata. Inside the plant, these compounds are metabolized and broken down into less harmful substances.
The second, and often more significant, step involves the root zone and the potting medium. The soil and roots contain a rich community of microorganisms, including bacteria and fungi. As VOCs diffuse downward, these microbes actively consume the pollutants, breaking them down into harmless byproducts that the plant or soil can use. This microbial activity in the root zone, often called the rhizosphere, is considered the primary engine for pollutant degradation in potted plant systems.
The Origin of Houseplant Purification Claims
The widespread association of common houseplants with air purification stems directly from a 1989 investigation known as the NASA Clean Air Study. This research was conducted to explore methods for improving air quality in sealed environments, such as future space stations. Scientists placed various common foliage plants into small, sealed plexiglass chambers.
Specific Volatile Organic Compounds (VOCs), including formaldehyde, benzene, and trichloroethylene, were injected into these chambers at high concentrations. The study then measured the rate at which the plants and their soil systems removed these toxins over a period of hours. Under these highly controlled laboratory conditions, the plants exhibited a substantial capacity to reduce the concentration of the tested pollutants. This experimental evidence formed the basis for the popular belief that houseplants are effective air purifiers in any setting.
Practical Air Quality Impact in Home Environments
While the Money Tree possesses the same natural biological mechanisms as the plants tested by NASA, its practical effect on air quality in a typical home setting is minimal. The main factor limiting the plant’s efficacy is the high rate of air exchange, or ventilation, that occurs in modern buildings. Even in a tightly sealed contemporary home, outdoor-to-indoor air movement constantly refreshes the air at a rate that far exceeds the filtering capacity of a few potted plants.
Translating the original laboratory results to real-world impact revealed significant limitations. Researchers have calculated the Clean Air Delivery Rate (CADR), a metric used for mechanical air purifiers, for individual plants. The CADR of a single houseplant is extremely low, often filtering less than one cubic meter of air per hour. To equal the air-cleaning effect of a standard mechanical air filter, a person would need to place between 10 and 1,000 plants per square meter of floor space.
This required density is physically unrealistic for a home environment. Most indoor air pollution sources, such as furniture or cleaning products, release contaminants continuously. Consequently, the amount of air purification a single Money Tree provides is negligible when compared to the volume of air and the constant introduction of new pollutants. Its contribution to overall home air quality is insignificant compared to opening a window or using a dedicated air filtration system.