In 1989, NASA conducted its famous Clean Air Study to see whether common houseplants might purify indoor air by removing toxins in addition to absorbing carbon dioxide and releasing oxygen. It worked, and while plants are still capable of absorbing harmful toxins in the air, new research suggests that potted plants’ ability to improve air quality in the home or office is largely overstated and buries a more effective solution to keeping the air clean.

1989年，美国国家航空航天局进行了著名的清洁空气研究，以观察普通室内植物除了吸收二氧化碳和释放氧气之外，是否还能通过排除毒素来净化室内空气。当时的研究证明这种方法起到了作用。但尽管植物能够吸收空气中的有害物质，新研究却表明，盆栽植物改善家庭或办公室空气质量的能力在很大程度上被夸大了，使我们忽视了一个保持空气清洁的更有效的办法。

Writing in the Journal of Exposure Science and Environmental Epidemiology, researchers found that natural ventilation of indoor environments dilutes concentrations of potentially harmful air pollutants much faster than a plant is capable of extracting them.

"The best way to have a healthy home is to try to reduce indoor emissions, ventilate well (especially when doing high impact emissions like cooking), and using filtration for certain pollutants (e.g. particulate matter),” study author Michael Waring of Drexel University told IFLScience.

Where NASA and similar studies went wrong is that they conducted their experiments in sealed chambers in laboratories, which do not accurately mimic the many factors that influence our indoor environments.

"In a small office, you would have to have somewhere between 100 to 1,000 plants to have the same air cleaning impact of ventilation at 1 air change per hour," said Waring.

That doesn't mean you should chuck out your plants just yet. Waring says that although houseplants do not clean the air under typical settings, houseplants have many benefits, most of which are psychological.