There are two rooms whose interior is lined with a non-adsorbent greenish material (meaning that organic compounds do not adhere). In the coming months, they will be used to mimic bedrooms, for a more precise measurement of how well the Neo P1 removes toxins from the air.
Neoplants’ proposition is appealing: perfectly pairing something that looks good in people’s homes and brings them joy (houseplants) with one of the biggest existential challenges facing humanity in general (slowly suffocating from pollutants). But proving that it really works is where things get tricky.
Browse most plant stores and you’ll be met with the promise of purified air: peace lilies and snake plants and ivy with little labels, pale blue or white, or some other color suggestive of purity, declaring that “this plant clean Air”. Patch, a popular online retailer, reserves an entire section of his website for “air-purifying houseplants.” Another vendor, Plantler, offers an Air So Pure bundle of spider plants, palms, and ferns.
Much of the support for these marketing efforts stems from 1989, when NASA worked with the Associated Landscape Contractors of America to test the ability of houseplants to remove toxins from the air. The resulting Clean Air Study suggested that, yes, houseplants could absorb certain pollutants, including VOCs like benzene, formaldehyde, and trichlorethylene. Less touted was the fact that these results were mostly not applicable to homes where these plants are often placed. Putting a plant in a sealed chamber, blowing pollutants on it for several hours (or days) and then recording the results, the researchers conceded, was not an accurate replica of normal houseplant conditions. This hasn’t stopped many researchers from running almost exactly the same experiment.
In 2019, however, researchers at Drexel University concluded thatfor the effects measured in these chamber experiments to be reproduced at any habitable scale, and even to match the rate of toxin removal already achieved by just opening a window, you would need between 10 and 1000 plants per square meter.
Richard Corsi, dean of the UC Davis College of Engineering, also takes offense at what he calls these “little glass chamber studies.” The problem, he says, is that to get their results, the researchers exaggerate the amount of air that would ever flow over a plant under normal conditions. The industry standard metric for the effectiveness of air filters is Clean Air Delivery Rate, or CADR, which combines separate measurements for airflow and the efficiency with which particulates are removed. The idea is that by combining these measures into a single metric, consumers are less likely to be fooled by, say, an air filter that is incredibly efficient at removing toxins, but only for a small amount of air.
Using data from previous plant studies and best-case calculations for CADR, Corsi says a roughly 200-square-foot bedroom would need up to 315 individual plants to reduce formaldehyde (and other VOC) levels by 50%. percent. More than 2,800 plants would be needed to obtain a 90 percent reduction. Expand that to an entire floor or house, and you’re feeding a dense jungle.