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 reserves in Iran with India and China the main markets for Iran’s gas exports. A recent report (December 11, 2011) from Iran's Petroleum Minister indicates that a large natural gas reserve was discovered inside Iran's side of the Caspian Sea. These reserves are estimated at 50 trillion cubic feet (1.42 trillion cubic meter). Natural gas reserves in Iran According to the Iran Petroleum Ministry, the proved natural gas reserves of Iran are about or about 17.8% of world's total reserves, of which 33% are as associated gas and 67% is in non associated gas fields. It has the world's second largest reserves after