Concordia researchers reveal dangerous by-products released
by a filter already in commercial use
(July 15, 2015) Imagine
if, in an effort to clean the air more efficiently, you were involuntarily
introducing chemicals more dangerous than the ones you were trying to scrub.
Concordia researchers have found that this exact situation is happening with a
type of air filter called photocatalytic oxidation (PCO), a product already on
the market. The chemical by-product? Formaldehyde, a known human carcinogen.
In a paper published in the journal Building and Environment,
recent doctoral graduate Lexuan Zhong and her supervisor Fariborz Haghighat
present the findings of their independent testing of the PCO systems, which
filter air using ultraviolet light. This is the first time the systems have
been independently tested.
“We were shocked that some of the gases to come through the
system are more dangerous than the original gas,” says Haghighat, who is a
professor with the Department of Building, Civil and Environmental Engineering
and 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 to evaluate and compare PCO systems themselves in the
absence of standards.
“That’s a big problem, there’s lots of confusion in the
market. We are trying to clarify that confusion and work on developing testing
methods,” says Zhong.