Indoor pollutants have been ranked among the top five environmental risks to public health: Stagnant indoor environments allow pollutants to build up and linger in greater amounts than we humans should be breathing in. Living and working in places rife with air contaminants and lacking decent ventilation can cause “sick building syndrome,” which can cause headaches, dizziness, nausea, and eye, ear, and nose irritation. Lucky for us, NASA scientists have been working to understand this problem and find solutions. Their space-age solution was an easy one that anyone can use: Use plants to clean the air.

So, how do plants clean the air? Plants absorb some of the particles from the air at the same time that they take in carbon dioxide, which is then processed into oxygen through photosynthesis. But that’s not all—microorganisms associated with the plants are present in the potting soil, and these microbes are also responsible for much of the cleaning effect .

Beyond air quality, plants just make people feel better and may make people smarter by allowing them to stay alert and reducing mental fatigue.

1. Garden Mum

In the NASA research, this plant was an air-purifying champion, removing ammonia, benzene, formaldehyde, and xylene from indoor air. Popular and inexpensive at garden stores, they can be planted outside after they’re finished blooming.

Pollutants removed: ammonia, benzene, formaldehyde, and xylene

2. Spider Plant

Spider plants are among the easiest houseplants to grow, making them a great choice for beginners or forgetful owners. A fan of bright, indirect sunlight, spider plants will send out shoots with flowers that eventually grow into baby spider plants or spiderettes.

Pollutants removed: formaldehyde and xylene

3. Dracaena

There are more than 40 different kinds of Dracaena plants, making it easy to find one that’s a perfect fit for your home or office. They’re common foliage plants with long, wide leaves that are often variegated with lines of white, cream, or red. Pet owners might want to select a different plant, however, as these are toxic to cats and dogs.

Pollutants removed: benzene, formaldehyde, trichloroethylene, and xylene

4. Ficus/Weeping Fig

Though the ficus is a tree in its native home of southeast Asia, when it grows indoors, it’s a hardy plant that ends up being between two and 10 feet tall. So why not get figgy with it? Grow this low-maintenance houseplant in bright, indirect light and allow the soil to dry out between waterings. Although this plant has some serious air-cleaning abilities, it can also be taken outside in late spring and brought back indoors when temperatures are warm and well above freezing.

Pollutants removed: benzene, formaldehyde, and trichloroethylene

5. Peace Lily

Peace lily plants are relatively small compared to many of the plants on this list, but they still pack some major air-cleaning abilities. Easy to grow, these plants will flower for much of the summer. Just be aware that those flowers (like all flowers) do contribute some pollen and floral scents to the air, so you may want to avoid having a room full of them. Put peace lilies in a shady spot and keep the soil moist without overwatering.

Pollutants removed: ammonia, benzene, formaldehyde, and trichloroethylene

6. Boston Fern

These plants prefer to clean the air from a cool location with high humidity and indirect light. They’re relatively easy to grow, but they do need to stay moist. Check the Boston Fern’s soil daily to see if it needs water, and give it a good soak once per month.

Pollutants removed: formaldehyde and xylene

7. Snake Plant/Mother-in-Law’s Tongue

Pollutants removed: benzene, formaldehyde, trichloroethylene, and xylene

8. Bamboo Palm

A superstar of filtering formaldehyde, these palms thrive in full sun or bright light. Part of the reason they can filter so much air is that they can grow to be pretty big—as tall as four to 12 feet high, making them exciting (and pet-friendly) indoor additions.

Pollutants removed: benzene, formaldehyde, trichloroethylene

9. Aloe Vera

In addition to being easy to care for, aloe makes some serious health claims. The plant’s leaves contain a clear liquid full of vitamins, enzymes, amino acids, and other compounds that have wound-healing, antibacterial, and anti-inflammatory properties, and there is some evidence that aloe may help (and is unlikely to hurt) skin conditions like psoriasis .

Pollutant removed: formaldehyde