Indoor air quality is a growing concern, and mold is a common household issue linked to excess moisture and poor air circulation. Beyond mechanical solutions, many people seek natural methods for improving their indoor environment. Incorporating common houseplants represents a simple approach to maintaining cleaner air and mitigating the conditions that allow mold to thrive. This strategy harnesses the natural biological processes of plants to manage airborne pollutants and ambient moisture levels.
How Plants Interact with Indoor Air Quality
Houseplants contribute to cleaner air through phytoremediation, which involves absorbing gaseous pollutants from the atmosphere. While photosynthesis primarily involves taking in carbon dioxide and releasing oxygen, plants are also capable of absorbing other airborne chemicals through the stomata on their leaves. These compounds are then transported down to the root system.
The most significant air-cleaning action often occurs within the potting mix itself. The soil is home to a robust community of microorganisms that use contaminants as a food source. As air circulates around the pot, these microbes break down volatile organic compounds (VOCs) into harmless substances, such as carbon dioxide and water.
Specific Varieties Known for Air Filtration
Several common indoor plant species have been studied for their ability to filter specific chemical pollutants found in household air. Research, including work initially conducted by NASA, identified plants capable of removing VOCs that off-gas from paints, furniture, and cleaning products. Benzene, formaldehyde, and trichloroethylene are common VOCs targeted.
The Snake Plant, or Sansevieria trifasciata, is valued for its capacity to remove benzene, formaldehyde, and xylene. The Spider Plant, or Chlorophytum comosum, is known for its effectiveness against formaldehyde and xylene. Peace Lilies (Spathiphyllum) filter multiple pollutants, including formaldehyde, benzene, trichloroethylene, and ammonia.
Different species of Dracaena, such as the Dracaena marginata (Red-edged Dracaena), also show strong filtration properties against chemicals like formaldehyde and xylene. Focusing on varieties with large leaf surface areas generally increases the potential for pollutant absorption.
Using Plants to Manage Indoor Humidity
Mold requires a moisture-rich environment, thriving when relative humidity levels exceed 60%. Plants influence ambient moisture through transpiration, a process where water is drawn up from the roots and released as vapor through the leaves. This action adds moisture to the air, which can be beneficial in overly dry environments, helping to maintain the optimal range of 40% to 60% relative humidity for human comfort and health.
Strategically placed plants can help stabilize moisture levels, but their placement and care require careful attention. Placing plants in well-lit areas with good air circulation helps ensure efficient transpiration without creating stagnant, overly humid pockets. It is important to avoid overwatering, as saturated soil can raise the humidity around the pot and encourage mold growth directly in the potting mix.
Realistic Expectations and Limitations
While plants offer a natural way to improve air quality and manage humidity, they are a supplemental tool, not a complete solution for established problems. The high rates of VOC removal observed in laboratory studies, like the NASA Clean Air Study, were conducted in sealed chambers. These results do not translate directly to real-world homes with constant air exchange and new sources of pollution.
To achieve comparable air cleaning performance in a typical building, one would need a significantly higher number of plants than is practical for most residential spaces. Plants cannot eliminate existing, widespread mold colonies; severe mold issues require professional remediation and structural repairs.
For plants to be effective, their leaves must be kept clean to maximize absorption. Owners must carefully monitor soil moisture to prevent the plants themselves from becoming a source of mold. Used correctly, plants are a valuable part of maintaining healthy, clean air post-remediation, but they are not a substitute for addressing the root causes of moisture problems.