Scientists have known for years that plants can take up common indoor air pollutants, improving the air quality for the occupants of homes and offices while not harming the plants themselves. One common pollutant is formaldehyde, which outgasses from many construction materials and is a potential source of health problems, especially in buildings with energy-saving, tight construction.
As reported in the Nov-Dec 2010 issue of HortIdeas, researchers in South Korea recently evaluated a wide range of indoor plants to see which were the most efficient at removing formaldehyde. They placed plants in growth chambers with a known initial concentration of the gas, then measured its cumulative removal at hourly intervals up to five hours. While all the plants tested removed some formaldehyde, those that removed at least 1.2 micrograms per cubic meter per square centimeter of leaf area after 5 hours were judged to be "excellent" air cleaners.
Interestingly, many of the top "removers" were ferns, including the top performer Osmunda japonica, Japanese royal fern. Others good air purifiers were Selaginella tamariscina, resurrection fern; Davallia mariesii, hare's foot fern; Polypodium formosanum, caterpillar fern; Pteris spp., Chinese brake fern and Botrychium ternatum, grape fern. Also high on the list were lavender and geranium (Pelargonium) species. Overall, the Osmunda species that removed the most formaldehyde was 50 times as effective as Dracaena deremensis,the plant in the study that removed the least, so if air cleaning ability is a priority, proper plant selection can make a big difference.