You know that rumor that plants can improve your air quality? Turns out it’s totally true.

A 1989 study by NASA tested common house plants to see if they could remove harmful chemicals from the air. Scientists put plants in sealed chambers and pumped in benzene, formaldehyde, and trichloroethylene–chemicals that are known carcinogens. Some of the plants that NASA used were able to remove up to 90% of the chemicals within 24 hours.

Plants take harmful chemicals out of the air and sequester them in their cells and roots. The lead scientist from this study, Dr. B.C. Wolverton, also released a follow up study where he added ammonia and xylene to the chemical mix, to similar effect.

But what about smoke from weed and cigarettes, some of the most common contaminants in homes? Cigarettes have formaldehyde in them, and it’s proven that plants can remove that, but the rest is theoretical—NASA did not explicitly prove that plants remove smoke from the air.

Here is a full list of the plants that NASA used. They are all common house plants, easy to find in your local nursery. Most are low-light and easy to take care of.

  • Bamboo palm
  • Chinese evergreen
  • English ivy
  • Ficus
  • Gerbera daisy
  • Janet Craig
  • Marginata
  • Mass cane/Corn cane
  • Mother-in-law’s tongue/Snake Plant
  • Peace lily
  • Pot mum
  • Warneckei