A Toronto Catholic high school has been closed after air ducts tested positive for asbestos.

The testing was done following work on the swimming pool and change rooms at St. Patrick Catholic Secondary School, located in the Greenwood and Danforth Avenues area.

“We sampled the tile grout in the change rooms and it was determined that it contained about 1.5 per cent asbestos,” Corrado Maltese, co-ordinator of occupational health and safety with the Toronto Catholic District School Board (TCDSB) told CityNews. “Although it’s not a lot of asbestos, it is still considered asbestos-containing and there was some concern that some of the dust in that construction area may have actually entered the ventilation of the school.”

The Ministry of Labour asked that the entire building be tested for the presence of asbestos. Four of the buildings’ 17 air ducts came back positive.

Maltese said ducts were cleaned and then as an added precaution he ordered further air quality tests to make sure none of the asbestos became airborne.

Fe de Leon, a researcher at the Canadian Environmental Law Association, says the board is taking the right steps in going above and beyond to make sure the children are safe.

“I think it’s a good start. I think, as it respects to areas where young people spend a good chunk of their days, it’s better to be cautious than not to,” she explained.

“There’s always cause for concern. The threshold for asbestos is set quite low but if you have opportunities to clean it up let’s do that.”

Students have been moved to a nearby school while the testing continues.

Asbestos in schools is nothing new. The TCDSB says 175 of their 201 buildings contain it and that any building built before 1990 likely contains some asbestos.

The TCDSB said that should the air quality testing results come back clean on Tuesday, St. Patrick Catholic Secondary School will reopen on Wednesday.

To read the TCDSB’s 2013 asbestos inspection survey click here.