Air quality degradation is not confined to industrial zones, urban areas or any outdoor environment. Modern buildings have become increasingly air-tight and insulated in the name of energy efficiency, which leads to the indoor accumulations of volatile organic compounds (VOCs), particulates and other airborne species. The result can be an increase in allergies, asthma symptoms and sick building syndrome, all of which might be alleviated by the use of high-efficiency particulate air filters.

Botanical approaches to purifying indoor air have been advocated, as some houseplant species have been shown to bioaccumulate or metabolize common pollutants. Acknowledging the air-tight construction of capsules designed for space missions and the potential for pollution buildup, NASA researchers have also examined the A pothos ivy plant is placed into a glass tube to test its ability to break down benzene or chloroform. Source: Mark Stone/University of Washingtonbiochemical mechanisms involved in plant detoxification.

However, a veritable forest of houseplants would be needed to efficiently remove toxins from indoor air. University of Washington researchers turned to genetic engineering to boost the detoxification capacity of the common pothos ivy. A rabbit gene – CYP2E1 – which encodes a VOC-degrading enzyme, was added to the ivy’s genome. This mammalian enzyme converts benzene into phenol and transforms chloroform into carbon dioxide and chloride ions.

Modified and control plants were placed in glass enclosures to which either benzene or chloroform gas was added. The gas concentrations remained the same in the control plant enclosures after 11 days. Chloroform levels declined by 82% after three days and were almost undetectable by day six in the transgenic plant systems. Benzene concentrations dropped by about 75% by day eight.

The researchers plan to increase the plants’ air purifying capabilities with the addition of a protein that targets formaldehyde. Their development could potentially result in genetically modified plant-based biofilters that remove VOCs from indoor air at appreciable rates.