A general term for acidic natural gases, natural or petroleum gas containing hydrogen sulfide, sulfur dioxide, or mercaptans. A concentration of 1 part per million is perceptible and 3 parts per million is toxic. Two sour gases associated with oil and gas drilling and production are hydrogen sulfide and carbon dioxide. Sulfur and nitrogen oxides, generated by oxidation of sulfur- or nitrogen-bearing materials, are also acidic but do not occur in the anaerobic conditions of the subsurface.
Subjects: Public Health and Epidemiology.