The furnace is on, the fireplace is lit and the garage door is closed.
Keeping the house, yourself and your family warm during frigid temperatures is a challenge with one particularly invisible, deadly risk: carbon monoxide (CO) poisoning.
The Centers for Disease Control and Prevention (CDC) estimates that 20,000 to 30,000 people in the United States each year suffer from CO exposure.
With no end in sight to the cold weather, the CDC has released precautionary measures homeowners and others can take to protect themselves from the odorless, colorless gas.
To view the agency's recommendations, click through the slideshow.