Natural gas tens of millions of structures that use the fuel, the individual risk of using natural gas is very low. Natural gas heating systems may cause carbon monoxide poisoning if unvented or poorly vented. In 2011, natural gas furnaces, space heaters, water heaters and stoves were blamed for 11 carbon monoxide deaths in the US. Another 22 deaths were attributed to appliances running on liquified petroleum gas, and 17 deaths on gas of unspecified type. Improvements in natural gas furnace designs have greatly reduced CO poisoning concerns. Detectors are also available that warn of carbon monoxide and/or explosive gas (methane, propane,
Natural Gas Choice feet of natural gas, respectively. Ohio has had Natural Gas Choice since 1997. More than 40 percent of the state's residential natural gas customers were participating in choice programs as of September 2008. Several major Ohio natural gas utilities in Ohio have plans to exit the function of supplying natural gas to customers, leaving the gas supply function to independent natural gas supply companies. In 2007, Ohio had 3,273,791 residential, 272,548 commercial, and 6,865 industrial customers. They consumed approximately 300, 159, and 295 billion cubic feet of natural gas, respectively. Currently, Ohio has 35 natural gas suppliers certified to participate