One common aerial pollutant involved in "sick building syndrome" is gaseous formaldehyde. In the research described here, plants of Ficus benjamina and Fatsia japonica were potted into a medium containing sphagnum peatmoss, perlite and sand.
They were then placed in chambers where they were grown in 12-hour days and exposed to an atmosphere containing two microlitres of formaldehyde per litre of air.
In one experiment, the pollutant was given in either the day or the night and the root zones of some plants were isolated by enclosing the pots in a Teflon bag. In another experiment, the aerial parts of the plant were removed and the roots and micro-organisms in the growing medium were killed by heat sterilisation.
Plants of both species were found to be effective at removing formaldehyde from the atmosphere, both in the light and in the dark.
However, while the aerial parts of the plants removed more formaldehyde during the day, the root-zone removed more at night. Very little was removed if the roots and the root-zone micro-organisms were killed.
Efficiency of Volatile Formaldehyde Removal by Indoor Plants: Contribution of Aerial Plant Parts Versus the Root Zone by Kim, Kil, Song, Yoo, Son & Kays (2008). Journal of the American Society for Horticultural Science 133 (4): 521-526. Members of ISHS can view the Journal of the American Society for Horticultural Science from the website www.ishs.org.