Phil Burns demonstrates the air purifying SCape Mask at his home in American Fork, Utah, Dec. 14, 2012. While most "preppers" discount the Mayan calendar prophecy, many are preparing to be self-sufficient for threats like nuclear war, natural disaster, famine or economic collapse.

Phil Burns inventories a backpack full of survival supplies at his home in American Fork, Utah, Dec. 14.

Employees construct a bunker at Utah Shelter Systems in North Salt Lake, Utah, Dec. 12. Shelter prices range from $51,800 to $64,900.

Hugh Vail inventories food storage at his home in Bountiful, Utah, Dec. 10.

Hugh Vail cuts firewood at his home in Bountiful, Utah, Dec. 10.

Mike Porenta prepares to ship emergency camp stoves at American Prepper Network's warehouse in Sandy, Utah, Dec. 10.