The players and coaches just didn’t realize it at the time.

Notre Dame coach Cory McCracken said about 18 of his 21 players showed signs of respiratory stress or illness during a 7-1 victory against De Pere at the De Pere Ice Center that evening.

With many of the players still experiencing symptoms on Friday, Notre Dame’s game against Ashwaubenon at the Cornerstone Community Center was postponed.

“We were trying to piece together things from (Thursday) night,” McCracken said about the junior varsity and varsity games against De Pere. “A bunch of really healthy high school athletes walked into the rink ready to play a game at 6, and between then and starting the first period out, it started in different phases for them.”

A test conducted by De Pere Ice Center rink manager Don Chilson on Friday morning discovered levels of nitrogen dioxide at the rink level, which happened due to a leak on the Zamboni and its propane tanks. Nitrogen dioxide is a byproduct of burning liquefied petroleum gas.