This study (2004) compared the rates of VOC removal (benzene  as the model VOC) by seven potted plant species/varieties.

High air-borne doses of benzene were removed in static test-chambers within a 24-hour period, including a dark period, and the removal rates were measured. Sampling was continued for the next two or more days with added concentrations of benzene. Several  plant morphological characteristics were also measured (i.e. leaf area, dry weight). Finally, the plant was removed for the measures of removal rates of the potting mix.

The tested plant species were Howea forsteriana (Kentia Palm), two variations of Spathiphyllum floribundum (var. Petite and Sensation), Dracaena deremensis (var. Janet Craig), D. marginata, Epipremnum aureum (Devil’s Ivy), and Schefflera actinophylla var. Amate (Queensland Umbrella Tree).

The study found, that the removal rates ranged from 12–27 ppm d–1 (2.5 to 5 times the Australian maximum allowable occupational level).

• All plants had a similar response: initially removal rates were slow, but increased typically after 2-4 days of exposure to the chemical
• Removal rates were maintained in light or dark
• Removal rates rose linearly with increased dose

The main agents of the benzene removal were the micro-organisms of the potting mix rhizosphere, but with some species, the plant also made a measurable contribution to removal rates by absorption. Potting mix samples from all plant species removed approximately 97 % of the benzene in 24 h, while the micro-organism cultures removed approximately 95 %.

The results of the study were consistent with already known and mutually supportive plant/soil-micro-organism interactions, and developments in microbially-based ‘biofilter reactors’ for cleaning VOC-contaminated air. Potted plant microcosm has a capacity to contribute greatly to healthier indoor air, and should be used as a foundation for the development of the plant/substrate system as a complementary biofiltration system.