The teachers' union at LaSalle's École des Découvreurs, where 43 people were sent to hospital due to a carbon monoxide leak in January, is taking its concerns to Quebec's labour tribunal.
The union — the Syndicat de l'enseignement de l'ouest de Montréal — wants answers about how the incident happened and financial compensation for affected teachers.
On Jan. 14, a gas leak at the school sent 35 students and eight staff members to hospital. Nine students lost consciousness, while others were nauseous, vomiting and dizzy as a result of their exposure to the deadly gas.
The union wants to shed light on what happened through testimony from staff, the school administration and the Marguerite-Bourgeoys school board (CSMB).
The idea is to "establish the employer's responsibility and, if necessary, to obtain compensation," said union president Mélanie Hubert.
The school board says it is conducting a separate internal investigation into the events in January.
In the coming days, an external firm will meet school staff to gather information, the board wrote in a notice sent to the school's employees.
The union is awaiting the results.
"The teachers understand that accidents happen," Hubert said.
"The crux of the matter is what happened between 8:30 and 9 a.m. when classes started and when ambulances and the fire department arrived around 11 a.m."
Montreal's public health board and police department are also investigating what happened.
No carbon monoxide detector
Documents obtained by Radio-Canada showed that there was a methane detector, but no carbon monoxide detector at the school.
The school board had claimed otherwise, but later sent a letter to parents saying additional checks revealed the detector in place lacked a sensor capable of detecting carbon monoxide.
Before that incident, Quebec law did not force school boards to equip their establishments with carbon monoxide detectors.
That changed when Education Minister Jean-François Roberge decreed that all schools boards are required to install detectors and inspect them regularly.