Ozone-eating pot plants promise cleaner office air

We all know that pot plants in the office help make the environment that little bit greener, but they could also make the air significantly cleaner and safer, says a team of US researchers.

According to research published in an American horticultural journal, common house plants could save up to two million people each year from a premature death resulting from indoor air pollution.

The paper, Effectiveness of House Plants in Reducing the Indoor Air Pollutant Ozone, has been published in the April-June issue of HortTechnology. It warns about the detrimental effect of ozone on human health. The gas, which is a valuable protection mechanism against UV rays in the upper atmosphere, is conversely dangerous when absorbed in concentrated amounts indoors.

Office equipment such as laser printers produce ozone, which lingers in the air. It is caused by the reaction of oxygen to high-voltage electricity, and can cause respiratory problems. It is also an irritant to the eyes, nose and throat.

The researchers, who come from Pennsylvania State University, tested the snake plant, spider plant and golden pothos in ozone-filled chambers. After concentrations of ozone injected into the chambers reached 200ppb, the ozone generator was turned off, and the group measured the time it took for the gas to deplete.

"On average, ozone depletion time ranged from 38 to 120 minutes per evaluation," the team said. "Ozone depletion rates were higher in the chambers that contained plants than within control chambers without plants, but there were no plant species differences."

The Environmental Protection Agency has said that people can recover relatively easily from the harmful effects of the gas following short-term exposure, but health effects may become more damaging and recovery less certain when exposures are longer.