Air filter might spew poison

Toronto: The expensive air filter that you installed in your house in the hope of getting pure air could actually be emitting poisonous gases, a study says. Concordia University researchers have found this is happening with a type of air filter called photocatalytic oxidation (PCO), a product already in the market.

The filter's chemical by-product is Formaldehyde, a known human carcinogen, says a study. "Some of the gases to come through the system are more dangerous than the original gas," said professor Fariborz Haghighat Concordia University research chair of energy and environment.

With countries like China and Korea eager to fix growing air pollution problems, engineers and consumers desperate for new technologies have been forced to try evaluating and comparing PCO systems themselves in the absence of standards. The battle against chemical contaminants is a challenge because gases come from so many sources - carpets, paint, treated wood, and then there are all the perfumed products we use individually.

The PCO system currently in use employs mechanical ventilation, where fresh air is pumped in from outside and taken out from inside, the method is not very energy efficient.