One group had plants in their apartments while the other did not. Various plants were grown, including Ficus elastica, Spathiphyllum spp, Epipremnum aureum and Fatsia japonica. Potted plants were introduced in October and assessments of sick-building syndrome were made immediately after that as well as in January, when the apartments were usually relatively airtight, and in July, when they were usually ventilated.
The health of one householder was also surveyed in detail. The residents apparently suffered symptoms of sick-building syndrome for up to two years after construction. Somewhat surprisingly, the symptoms were not significantly reduced either by the presence of plants alone or by ventilation alone, but they were reduced when these factors were combined.
Some symptoms of mental illness were also lowered when plants were present in summer. Although plants were able to reduce the toxicity of air in new buildings, the benefit was found to be greater when ventilation was also used.
Evaluating the Relative Health of Residents in Newly Built Apartment Houses According to the Presence of Indoor Plants by Kim, Park, Yang, Kim, Lee, Shin and Lim (2010). Journal of the Japanese Society for Horticultural Science 79 (2): 200-206. The authors' abstract is available online at www.jstage.jst.go.jp/browse/jjshs1.
Dr Ken Cockshull is emeritus fellow at Warwick HRI