Many plants can help contribute to cleaner air quality, helping to filter out harmful chemicals and increase oxygen levels. Ferns are particularly well adapted to use in apartments and small houses, because they require minimal upkeep, grow in a wide range of climates, and are very beneficial to air quality.
NASA was the first organization to do substantial research into the role plants could play in cleaning and maintaining air quality. During the SkyLab project, NASA began looking at plants such as ferns as cost-effective, low-upkeep solutions to keeping future space stations fit for human habitation. Various houseplants are able to draw in harmful chemicals from the air and fix them in their soil, where they become relatively harmless.
Although people have known for some time that plants draw in carbon dioxide and respirate oxygen during photosynthesis, which helps improve air quality for animals, it is only in the last few decades that researchers have discovered their benefits go far beyond oxygen enrichment. Three common pollutants, trichloroethylene, benzene, and formaldehyde, can all be absorbed and fixed by common plants.
In the modern age, building has become a fairly toxic endeavor. With the heavy use of plastics in everything from sealants to carpeting, new houses are full of off-gassed toxins that can cause low-level sickness in inhabitants. These symptoms are generally classed as being part of Sick Building Syndrome, and ferns and other plants can help reduce or eliminate the symptoms entirely.
Formaldehyde is a toxin present in nearly all modern buildings. The EPA estimates an average 800 cubic foot (23 cubic meter) room contains roughly 1,800 micrograms of formaldehyde. Formaldehyde can cause symptoms ranging from nausea and headaches to dizziness, skin irritation, and shortness of breath. It is estimated that common Boston ferns can remove a full 1,800 micrograms of formaldehyde from the air per hour. This means that placing the plants in a room can virtually eliminate formaldehyde that may be introduced through off-gassing.
The EPA recommends placing two plants for each 100 square feet (9 square meters) of floor space. While ferns are certainly some of the easiest to look after, and grow in a dynamic range of environments, many other household plants can help absorb dangerous toxins as well. The areca palm, for example, is thought to be one of the best absorbers of xylene, another dangerous toxin. Plants such as dwarf date palms, spider plants, philodendrons, peace lilies, and snake plants are also great for improving air quality and reducing airborne pollutants.