To understand if Haworthia plants purify the air, we must first examine the fundamental processes plants use to interact with their aerial environment. The primary mechanism is photosynthesis. During this process, plants absorb carbon dioxide (CO2) from the air through tiny pores on their leaves called stomata. Inside the leaf, using light energy, they convert CO2 and water into sugars for growth, releasing oxygen (O2) as a by-product. This exchange directly alters the composition of the immediate air. Additionally, plants undergo respiration day and night, a process where they take in O2 and release CO2, though the net effect of photosynthesis far outweighs respiration during daylight hours. A secondary, less visible process is phytoremediation, where plants can absorb certain volatile organic compounds (VOCs) through their leaves and roots, potentially breaking them down or incorporating them into plant tissue.
Haworthia species, like other plants, engage in photosynthesis and respiration and therefore contribute to the cyclical exchange of oxygen and carbon dioxide in a room. However, their unique physiological adaptation, known as Crassulacean Acid Metabolism (CAM), sets them apart from most common houseplants. Most plants open their stomata during the day to take in CO2 for photosynthesis. CAM plants, adapted to arid environments, keep their stomata closed during the hot, dry day to prevent water loss. Instead, they open their stomata at night to absorb CO2, which is stored as an acid and then used for photosynthesis the following day while the stomata remain closed.
This nocturnal gas exchange means that Haworthias release the majority of their oxygen at night. From a human perspective, this is a distinctive feature, as it contrasts with the diurnal cycle of most plants. In terms of purifying the air of VOCs like benzene or formaldehyde, Haworthia possesses the same basic capabilities as other green plants. Its leaves and root-associated microorganisms can absorb trace amounts of these pollutants. However, its slow growth rate and relatively small leaf surface area compared to larger, faster-growing plants like a Peace Lily or Devil's Ivy mean the rate of purification is correspondingly modest.
The famous NASA Clean Air Study of 1989 is often cited as evidence for houseplants purifying air. This study demonstrated that certain plants could remove significant amounts of VOCs from a sealed laboratory chamber. While Haworthia was not specifically tested in that study, other succulents with CAM photosynthesis, like the Snake Plant (Sansevieria), were included and showed positive results. It is reasonable to extrapolate that Haworthia would have a similar, albeit likely smaller due to size, capacity.
The critical point from a plant science viewpoint is the difference between a controlled chamber and a real-world home or office. The NASA experiments were conducted in a static, sealed environment, whereas a typical room has constant air exchange with the outside via doors, windows, and ventilation systems. To meaningfully impact air quality through plants alone, studies suggest one would need a very large number of plants per square foot—an impractical density for most spaces. Therefore, while Haworthia does engage in air-purifying processes, its contribution in a normal, ventilated room is biologically minimal compared to the effect of simply opening a window.
Beyond the direct biochemical exchange of gases, Haworthia contributes to a healthier indoor environment in other significant ways. Like all plants, it undergoes transpiration, the process of releasing water vapor through its leaves. This slightly increases the humidity in its immediate vicinity. In air-conditioned or heated rooms, which often have dry air, this can help alleviate minor respiratory irritations and dry skin. Furthermore, the presence of plants like Haworthia offers documented psychological benefits. The act of caring for a living organism and the visual connection to nature can reduce stress, improve mood, and enhance concentration. For a plant like Haworthia, which is low-maintenance and thrives indoors, it provides these benefits without demanding significant time or expertise, making it an accessible tool for promoting mental well-being.
