Sulfur can be ignited by a flame or spark and burns in open air, giving off fumes of sulfur dioxide. The accumulation of sulfur dust or fumes can be sparked off in a potentially explosive reaction.
Sulfur has been produced by the use of traditional mining practices through the later part of the 20th century. The majority of sulfur that is produced in the world as of 2014 comes from the treatment processes that are used on gas and oil in refineries. Sulfur, in the form of sulfuric acid, is also produced during the smelting of ferrous and nonferrous metals.