Genetically Modified Houseplants Are Coming to Clean Your Air

Neoplants says its pothos has superior purification properties—but you’ll still need a lot of them to get the job done.

At an old shoe factory on the outskirts of Paris, new life is taking shape. Behind a heavy door, a bank of PCR machines multiplies plant DNA molecules by hundreds of billions every few hours. Inside a gleaming white chamber, tiny emerald shoots are coaxed from single cells, unfurling in millimeters over a period of months.

“It’s like a biologist’s wet dream,” says Patrick Torbey, chief technology officer of Neoplants, a Parisian startup taking a multimillion-dollar punt on the air we breathe. Torbey grabs one of the small, plastic receptacles from inside the chamber and squints at his verdant creation: Nestled in a jelly-like growing medium, it looks like a canapé—or, possibly, the future.

This is the Neo P1—a genetically modified houseplant that the company claims could help combat indoor air pollution. P1 is a modified form of golden pothos—more commonly known as devil’s ivy—one of the world’s most ubiquitous and easy-going houseplants. Although its yellow-green hues appear familiar, P1’s DNA has been tweaked to enhance its ability to extract volatile organic compounds (VOCs) from the air, including formaldehyde, benzene, toluene, ethylbenzene, and xylene, which are prevalent in indoor spaces.

These genetic adjustments also—crucially in the case of the P1—allow the plant to convert the VOCs it absorbs into substances like sugar and CO2 that it can use to carry on growing. Once it’s outgrown the agar, P1 will be planted in soil enriched with biochar (a common gardening additive) in a pot designed to maximize airflow, and sold with a pack of three Power Drops (bacteria, to be added to the soil each month to help the plant metabolize the VOCs it absorbs). Due on shelves later this year, P1 will retail for $179, or around £145—roughly 10 times the cost of an ordinary golden pothos plant, or comparable to that of a keenly priced Honeywell HEPA purifier.

So far, Torbey, who has a PhD in genome editing, and his cofounder Lionel Mora, an ex-Google product marketer, have collected $20 million in venture funding from firms including True Ventures and Collaborative Fund.

Much of the money has gone toward fitting out Neoplants’ new space on the north side of the French capital. Over the past two years, it’s been stripped and gutted, whitewashed, and then refitted to spec with every gadget Torbey could tick off his wishlist. There are mass spectrometers, fume cupboards, and growth chambers. Magnetic stirrers fidget next to cabinets stocked with glass flasks and petri dishes.

There are two rooms whose insides are coated in a greenish non-adsorbent material (meaning organic compounds won’t stick to it). In the months to come, they’ll be used to mimic bedrooms, for a more accurate measurement of how well Neo P1 strips toxins from the air. 
Neoplants’ proposition is an attractive one: neatly pairing something that looks nice in people’s homes and brings them joy (houseplants) with one of the biggest existential challenges facing humanity at large (slowly choking to death from pollutants). But proving that it actually works is where things get thorny.

Browse most plant shops and you’ll be met with the promise of purified air: peace lilies and snake plants and ivy with little tags—pale blue or white, or some other colour suggestive of purity—declaring that “this plant cleans air.” Patch, a popular online retailer, reserves an entire section of its website for “air-purifying indoor plants.” Another vendor, Plantler, offers an Air So Pure package 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 assess 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 trichloroethylene. Less touted was the fact that these results mostly could not be applied to the houses these plants are often placed in. Putting a plant in a sealed chamber, blowing pollutants over it for multiple hours (or days), and then recording the results, the researchers admitted, was not an accurate replication of normal houseplant conditions. This has not stopped many researchers since from conducting almost exactly the same experiment. 

In 2019, however, researchers at Drexel University concluded that, in order for the effects measured in these chamber experiments to be reproduced at any livable scale, and to even match the rate of toxin removal already achieved by just opening a window, you’d need anywhere between 10 and 1,000 plants per square meter. 

Richard Corsi, dean of the College of Engineering at UC Davis, also takes umbrage with what he calls these “little glass chamber studies.” The issue, he says, is that to get their results, researchers exaggerate the amount of air that would ever flow over a plant in normal conditions. The industry’s standard metric for the effectiveness of air filters is clean air delivery rate, or CADR, which combines separate measures for airflow and how efficiently particles are removed. The idea is that, by combining these measurements into a single metric, consumers are less likely to be misled by, for instance, an air filter that is incredibly efficient at removing toxins, but only for a small amount of air.

Using data from past plant studies and calculations based on the best case scenario for CADR, Corsi says that a bedroom of approximately 200 square feet would need as many as 315 individual plants to bring formaldehyde (and other VOC) levels down by 50 percent. To get a 90 percent reduction would require more like 2,800 plants. Scale that up to a whole flat or house, and you’re nurturing a dense jungle.

So is Neoplants’ genetically modified houseplant any better? The company’s sales materials reference the 1989 study, and claim the P1 is “30 times better than top NASA plants” when it comes to removing VOCs. But this was a lab-based study: Neoplants pumped formaldehyde, benzene, toluene, and xylene over a P1 sample contained inside a 35-liter glass chamber, and then compared the outputs. Field tests are yet to yield reliable results, but the hope is that the new lab, with its specially designed non-adsorbent rooms, will allow more true-to-life testing in the future.

There’s no CADR measurement to compare the P1 with mechanical air purifiers either. Instead, Neoplants offers a “CADR by weight” to reflect the varying sizes of different plants. Even if the P1 is 30 times better than a traditional houseplant, you would still need a lot of them to clean the dirtiest air. 

A new metric might be required for this product category, Mora argues, because plants—unlike traditional air purifiers—don’t get switched on and off (although they do have extended dormant periods in most years). Neoplants has hired two people to devise a measurement that better suits its purposes.

Right now, P1 amounts to trays of tiny shoots stored in growth chambers. It takes six months to take each plant from a single cell to a shoot of a few inches in height. More than 30,000 people have signed up for a waiting list via the Neoplants website; interested parties include hoteliers and real estate developers. Mora is cutting deals with growers in Florida who’ll be able to reproduce their plants at scale. (The US, where the regulatory process for clearing genetically modified products is more straightforward, will be Neoplants’ launch market).

The lab move-in isn’t quite complete—a workman’s brush props open the front door, fresh tarmac is being flattened into potholes in the courtyard—but the new facilities will enable Mora and Torbey to run more rigorous, realistic tests. P2 is already in the works, and the business is already exploring how its gene-editing technology could be deployed in carbon capture or phytoremediation, through which plants are used to absorb toxins from contaminated environments.

The company is banking on a bit of patience and a dose of belief—green shoots need time to grow. “It will be the first time in history that such a product exists,” says Mora. “The first computers, they weren’t so great. But they were revolutionary.”

Genetically Modified Houseplants Are Coming to Clean Your Air

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