MONTREAL - An air crisis at the French language St. Gerard School in Villeray has forced 424 students to pack up.

The students evacuated the school Wednesday and will attend classes at Ahuntsic College until January 20. After that it's on to a yet-to-be determined school for another 18 to 24 months.

The students and staff were forced to make the switch due to air quality issues stemming from mould.

Parents and staff of the school on Berri between Cremazie and Liege have complained of the air quality at the 85-year-old school.

One mother has seen the results of the mould every day. Her 11-year-old son has been helpless in his battle with a serious case of asthma.

"Now the doctors at Ste-Justine said you have to set an appointment with the asthma clinic because we don't understand why we can't control his asthma," said Chantal Laperriere, who is on the school's parents committee.

Meanwhile her six-year-old daughter also attends the school and saw a recurrence of symptoms since returning after the holidays. "Maybe it's in relation or not, I don't know, but we think because during the Christmas Holiday it was fine," she said.

Parent Tibe Medeiros has also seen his six-year-old suffer.

""Yeah he's been sick since last year. We didn't know. He had so many things," he said.

Anne Poulin's five-year-old also had bronchitis since entering the school. "We're going to get him healthy now and it's going to be resolved," she said.

The teachers' union has complained that the board was a bit slow to detect the serious problems.

"We consider it a little bit too late after five different schools have had problems," said Josee Verreault of the union.

"It's a kind of mould that grows on masonry," said Dr. Louis Drouin of Montreal Public Health. "Our hypothesis is that it's from chronic infiltration of water in the masonry,"

The mould contains several fungal species, including a concentration of a dangerous type of mould for which there is no tolerance, according to Health Canada. Extensive decontamination will be required.

The damage is believed to predate water infiltration issues which hit the school in November 2010.

Last month, the CSDM announced the launch of a $10 million air quality program. It will focus largely on schools where there were water looks in the roof, masrony or basement.

With a file from The Canadian Press