Bosses at the Motherwell campus of New College Lanarkshire have now confirmed that an environmental issue sparked a shutdown last month.
What was described as “a routine air inspection” in two rooms led to a temporary closure of the engineering block on Wednesday, January 22.
A college spokesperson explained: “We are committed to the health and wellbeing of our staff students and external partners and took the decision to close the block.
“During the break in college semesters very few classes were affected and staff were supported with alternative working arrangments.
“Although the inspection confirmed there was no identified risk, the closure allowed for a deep clean and further testing to be carried out as a precautionary measure.
“This took place ahead of the new academic semester and the building re-opened as planned on Monday, January 27.”