Safety

Do houseplants improve indoor air quality?

March 06, 2026 1 min read

Houseplants can improve indoor air quality, but the improvement in a typical home is modest rather than significant. The original NASA Clean Air Study in 1989 demonstrated that houseplants absorb certain volatile organic compounds (VOCs) in controlled laboratory conditions. Subsequent research has shown that the number of plants required to produce a meaningful air purification effect in a normally ventilated home is far larger than most people keep. Estimates range from 100 to 1,000 plants per 100 square metres of floor space to have a measurable effect on VOC levels. The more grounded benefit of houseplants for indoor environment is the increase in humidity through transpiration, the psychological wellbeing effects of greenery, and the marginal improvement in CO2 cycling.

What the Research Actually Shows

The NASA study was conducted in sealed chambers with individual plants and specific chemical concentrations, which are very different conditions from a normally ventilated living room. In realistic home conditions with normal air exchange through windows, doors, and ventilation systems, VOCs are diluted and removed through air exchange far more quickly than plants can absorb them. The phytoremediation effect that plants demonstrate in sealed conditions is largely irrelevant in a normally ventilated space.

More recent research has focused on the soil microbiome as a potential air quality contributor, beneficial soil bacteria process certain compounds as efficiently as the plants themselves. Some studies suggest that the soil and root zone activity contributes as much or more than the plant leaves in VOC processing. This is an emerging area of research rather than established guidance.

The Best Houseplants for Air Quality

If you are choosing plants with air quality benefits in mind, the species most frequently cited in research for high VOC-absorbing capacity include Peace Lilies (Spathiphyllum), Spider Plants (Chlorophytum comosum), Boston Ferns and Dracaenas. All are widely available, relatively easy to keep, and perform well in bright to medium indirect light positions. Our Epipremnum collection and fern range include species frequently cited in air quality research.

Frequently Asked Questions

Getting houseplants for air purification is not unreasonable, but it is worth doing with realistic expectations. The air purification effect in a real home is small, you would need a very large collection to make a measurable difference to VOC levels. The aesthetic, humidity, and wellbeing benefits are more reliably significant for most people. Getting plants because you enjoy them and find them beneficial for your environment is well supported; getting a specific Peace Lily as an air purifier in a small room and expecting significant air quality improvement is less well-supported by the evidence.
Yes, but minimally in a normally ventilated space. Plants absorb CO2 during photosynthesis (daylight hours) and release CO2 at night through respiration. In a sealed, plant-dense space over a long period, CO2 levels would decrease during daylight hours. In a normally ventilated home with a few plants, the effect on overall CO2 levels is negligible. The most effective way to reduce CO2 indoors is ventilation.
The concern is that plants respire and release CO2 at night, potentially raising CO2 levels in a closed bedroom. In practice, a few plants in a bedroom produce a negligible amount of CO2 compared to one sleeping person, and normal ventilation easily handles it. This is a genuine but trivially small effect. The practical conclusion is that plants in bedrooms are safe and often beneficial.
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