George Walden, 82, and his wife Beatrice were at home in bed when they were startled by a loud alarm. The couple quickly opened their doors and windows to ventilate their house and then ran outside.
Days after the scary experience they are grateful their carbon monoxide detector prevented anyone from getting hurt.
"As the carbon monoxide builds up you might pass out if it's strong enough so you can die and some people do," Walden said.
In 2011, carbon monoxide poisoning killed four people in Oakhurst. In these 20 degree foothill temperatures, firefighters worry more people may be putting themselves in danger.
"People leave their homes closed up to stay warm and because of that you don't get the fresh air in and using natural gases or propane gasses you always get carbon monoxide," said Cal Fire Battalion Chief Chris Christopherson.
Late last month firefighters went to a call after a woman cooking for Thanksgiving was also poisoned by the gas.
"We had to clear the rest of the air out of the home, had Sierra Ambulance come out and put her on oxygen and stand by with her until her blood gases got to the correct levels," Christopherson said.
Carbon monoxide is emitted from sources such a portable heaters, fire places and stoves.
Symptoms of a poisoning include dizziness, fatigue, headaches and nausea. People are required by law to have a working detector installed in their home.