Asphyxiant gas can smell the odorants, and assigning a different smell to each gas may be impractical. Another difficulty is that most odorants (e.g., the thiols) are chemically reactive. This is not a problem with natural gas intended to be burned as fuel, which is routinely odorized, but a major use of asphyxiants such as nitrogen, helium, argon and krypton is to protect reactive materials from the atmosphere. The dangers of excess concentrations of nontoxic gases has been recognized for centuries within the mining industry. The concept of black damp (or "stythe") reflects an understanding that certain gaseous mixtures could lead to
Natural gas in the United States up 0.13 percent of natural gas consumption in 2014. The natural gas industry in the United States goes back to 1821, when natural gas was discovered and used in Fredonia, New York. From the start, the market for natural gas was limited by pipeline technology. The gas for Fredonia, New York in 1821 was supplied through wooden pipes, which were incapable of carrying gas for long distances. In the 1800s, residences in most cities were supplied with town gas generated from coal at local "gashouses." The gas was carried in cast iron pipes, introduced in 1843, typically with bell-and-spigot joints