A buildup of pet hair clogged an Orléans couple's gas boiler last month, killing the man and sending the woman to hospital with severe carbon monoxide poisoning, Ottawa police said Friday.

"The home's gas boiler had a buildup of animal hair that caused very poor ventilation," police said in a news release.

The couple had removed the batteries from the home's carbon monoxide detectors, police said.

"The house was equipped with two combination smoke/CO detectors, which had been beeping," the news release said. "Thinking they were defective, homeowners removed the batteries from the device ultimately resulting in this tragedy."

First responders arrived at the house on Phoenix Crescent around 10:45 a.m. on Nov. 19 after a friend found the couple unresponsive.

The man, 75, was found dead at the scene. The woman, also 75, was transported to hospital in life-threatening condition, and was treated in a hyperbaric chamber.

Firefighters said CO readings inside the home were 600 parts per million, with readings closer to 700 parts per million in the basement.

Carbon monoxide levels inside the home were found to be dangerously high. (Stu Mills/CBC)

Police said they released the information to prevent similar tragedies.

"This is a reminder to clean gas boilers yearly, to keep fresh batteries in your carbon monoxide (CO) and smoke detectors. It is recommended to have a separate CO detector from your smoke detector so a leak is easier to determine," police said.

"If the CO alarm sounds, immediately move to a fresh air location outdoors or by an open window or door. Make sure everyone inside the home is accounted for. Call 911 from a safe location and stay there until emergency personnel arrive."