Aloe vera, a succulent known for its spiky, fleshy leaves, has been a fixture in homes for generations, primarily valued for the soothing gel found inside its leaves. It is often considered a natural remedy for minor burns and skin irritations. Over time, a widespread belief has emerged that the Aloe plant also cleans indoor air by significantly reducing common airborne contaminants. This article will examine the scientific basis for this claim and determine how accurately it reflects the reality of indoor air quality.
The Origin of the Air Purification Idea
The idea that common houseplants, including Aloe, can purify the air largely stems from the 1989 NASA Clean Air Study. This project was designed to explore methods for detoxifying the air in sealed environments, such as future space stations. Researchers placed various plants, including Aloe vera, into small, sealed glass chambers and introduced specific gaseous chemicals. The study documented the plants’ ability to remove these contaminants over a 24-hour period under those specific, isolated conditions. While the promising results were significant for developing closed-loop life support systems, the original context of the experiment is often overlooked today.
The Science Behind Plant Air Filtration
Plants like Aloe interact with indoor air pollutants through two distinct mechanisms, primarily targeting volatile organic compounds (VOCs). These VOCs, which include substances like formaldehyde and benzene, are commonly emitted from household items such as cleaning supplies, furniture, and building materials. The first mechanism involves the leaves, which possess tiny pores called stomata used for gas exchange, through which the plant absorbs a portion of the airborne chemicals.
The second, and often more effective, mechanism involves the root system and the potting soil. Pollutants absorbed by the leaves are sometimes translocated to the roots, while many airborne chemicals are drawn directly into the soil. The microorganisms and bacteria living within the soil are responsible for the majority of the detoxification process. These microbes break down the VOCs, metabolizing them into less harmful substances. The overall efficiency of this biological process depends heavily on the health and size of both the plant and the microbial community in its soil.
Real-World Effectiveness and Practical Needs
While the mechanisms of purification are scientifically sound, translating laboratory results to an average home environment reveals significant limitations. The NASA study used sealed chambers where pollutants remained trapped, allowing the plant system maximum time to work. In contrast, a typical home is an open system with constant air exchange through windows, doors, and ventilation systems.
This natural airflow rate, often measured in air changes per hour, vastly outpaces the slow rate at which a single houseplant can remove pollutants. Air purification effectiveness is measured by the Clean Air Delivery Rate (CADR). Mechanical air purifiers typically range from 100 to 400 cubic meters per hour, while a single houseplant has a CADR between 0.02 and 0.1 cubic meters per hour. To achieve a measurable reduction in VOCs, one would need an impractical concentration of plants, estimated at 10 to 100 medium-sized plants per 100 square feet. Additionally, Aloe requires adequate light to function optimally, diminishing its air-cleaning capacity in low-light areas.
Beyond Air Purification: Other Benefits of Aloe
The value of keeping an Aloe vera plant extends beyond air purification. The primary and most well-established benefit is the clear gel found inside its leaves. This gel is used topically to soothe minor skin irritations, small cuts, and superficial burns, offering a readily available remedy in the home.
The psychological benefits of incorporating greenery are also notable. Studies suggest that the presence of houseplants can contribute to a reduction in stress levels and an improvement in mood and concentration. Plants also release moisture into the air through transpiration. While not a substitute for a humidifier, a collection of indoor plants can contribute to a slight increase in ambient humidity, which is beneficial in dry environments.