The University of Hong Kong has alarmed air-quality experts by advising students living in its formaldehyde-plagued new residential halls to switch on air conditioners to ensure fresher air.
Students moving into the Kennedy Town quarters, after initially being delayed by the discovery of excessive levels of the cancer causing pollutant, were told lower temperatures would cut emissions of the toxic substance.
But Professor Yau Yiu-hung, of the Open University's school of science and technology, warned closing windows and turning on air-conditioners was not good for students' health as it would limit the amount of fresh air getting into the rooms.
"If students turn on the air conditioners, they'd better switch on the vent button to allow fresh air in," the indoor air quality specialist said.
He added that while cooler air would cut formaldehyde emissions the problem stemmed from accumulation of the substance and without ventilation the levels would rise again in a few days. City University ventilation specialist Professor John Lin agreed that students should open the fresh air vents on their air conditioners.
But he reiterated that opening all windows would ensure better dilution of pollutants.
"The problem facing the university is the hot weather, which is intolerable to students without air-conditioning," Lin said.
Students who moved in yesterday found the rooms satisfactory. "Ventilation is good and there is no bad smell at all," a first-year accounting and finance student from Malaysia said.
But an engineering postgraduate student from Shenzhen said the windows of his room were closed when he checked in.
The students' off-campus stay at hotels in the past seven days - after the halls were ruled out of bounds because of toxic formaldehyde - has cost the university more than HK$1 million.
The students' union will hold a referendum from Monday to Wednesday to gauge students' views on whether deputy vice-chancellor Professor Roland Chin and dean of student affairs Dr Albert Chau Wai-lap neglected their duties in handling the formaldehyde problem.