"We talked to the paramedics who worked on Amanda and they didn't know what they were working on, because they didn't feel so good themselves," Ken Hansen said.

The U.S. Centers for Disease Control and Prevention says about 20,000 people a year visit a hospital for treatment of CO poisoning. About 4,000 are admitted to the hospital, and more than 400 die.

The state Health Department said that between 2012 and 2014, the most recent figures available, 19 Niagara County residents were treated in emergency rooms because of carbon monoxide poisoning. Only three were admitted to hospitals, and none died. In Erie County during the same period, 84 people were treated, nine were admitted, and three died.

The Pinzels went to bed as usual on the night of Dec. 27, but trouble started when Laurie got up to use the bathroom about 2 a.m.

"I passed out on the bathroom floor and I hit my face. My face was so sore I couldn't fall back asleep," she recalled. Later, she was found to have suffered a concussion.

"A little while later my son had to go to work and he had a terrible headache, so my husband looked at both us and he said, 'Something's not right,'" Laurie said.