Debunking the Myths About Plants and Air Purification.
For years, it was widely believed that keeping plants in the bedroom was unwise due to concerns that they might deplete oxygen levels. The idea was that plants, by their natural processes, would consume oxygen, potentially leading to lower levels in the room. However, this notion ignored a simple fact: a person consumes far more oxygen than a plant. People don’t worry about oxygen depletion when sharing a bed with another person, so there’s no reason to be concerned about a plant. In fact, some plants, like aloe vera and certain orchids, engage in a unique process known as CAM (Crassulacean Acid Metabolism), where they absorb carbon dioxide and release oxygen during the night.
Another common belief is that plants can purify the air. This idea gained popularity after a NASA study in 1989 suggested that certain plants were effective at filtering volatile organic compounds (VOCs) like benzene, trichloroethylene, and formaldehyde. These substances, which can be found in tobacco smoke, paint fumes, lacquers, solvents, and some wood products, were found to be efficiently captured and eliminated by plants like gerbera, peace lily, sansevieria, bamboo palm, and ficus. For instance, the study highlighted gerbera as particularly effective at removing benzene and trichloroethylene, while bamboo palm was noted for its ability to remove formaldehyde.
For the past 30 years, this NASA study has often been cited as evidence that plants can purify indoor air. However, what is often overlooked is the specific conditions under which the NASA experiments were conducted. Since the study was designed to simulate conditions on space stations, the tests were carried out in tightly sealed, confined spaces.
Re-evaluating the Evidence
In late 2019, a study published in the journal Nature revisited the findings of NASA’s research from 30 years earlier. The authors clarified that while potted plants do have the ability to remove airborne VOCs, this effect is only significant in small, sealed environments over extended periods.
The Nature study, which reviewed 12 studies and nearly 200 previous experiments, concluded that in a typical indoor setting, between 10 and 1,000 plants per square meter would be required to achieve the same level of VOC removal as simply ventilating the room for an hour. Furthermore, the NASA study had only tested 12 plant species, including aglaonema, common ivy, Brazilian trunk, chrysanthemum, and various types of dracaena, alongside the five previously mentioned.
In 2018, researchers from the University of Washington made a breakthrough by genetically modifying a pothos ivy (Epipremnum aureum), a common and easy-to-care-for plant, to remove chloroform and benzene from the air more efficiently than other species. They introduced a protein called cytochrome P450 2E1, found in the human liver, which can transform these harmful compounds.
To test the effectiveness of this modification, the genetically engineered plants were placed in glass tubes filled with benzene and chloroform. After three days, the concentration of chloroform was reduced by 82%, and after eight days, benzene levels dropped by 75%, as reported by the university.
Conclusion
In conclusion, while it is true that some plants can remove certain chemical compounds from the air, their effectiveness is limited under typical indoor conditions. To achieve significant air purification, either a large number of plants would be required, or the plants themselves would need to be genetically modified. Therefore, while plants offer various benefits, their ability to purify air in a meaningful way is not as potent as once believed.