Occupational Exposure Values - Compiled by ACGIH
(shown for reference only - verify latest values)
ACGIH Values - Sulfur Dioxide | SO2
Threshold limit value (TLV): 0.25 ppm, 0.65 mg/m3 STEL
OSHA PELs - Sulfur Dioxide | SO2
Permissible Exposure Limits: 5 ppm, 13 mg/m3 TWA
NIOSH RELs - Sulfur Dioxide | SO2
Recommended Exposure Limit (REL): 2 ppm, 5 mg/m3 TWA; 5 ppm, 13 mg/m3 STEL
Sulfur dioxide is a colorless gas with a pungent odor. It is a liquid when under pressure, and it dissolves in water very easily. The primary sources of sulfur dioxide emissions are from fossil fuel combustion and natural volcanic activity. Sulfur dioxide in the air comes mainly from activities such as the burning of coal and oil at power plants or from copper smelting.
Sulfur dioxide is primarily produced for sulfuric acid manufacture. Sulfur dioxide is also used as a pharmaceutical aid and antioxidant. Sulfur dioxide is sometimes used as a preservative for dried apricots, dried figs, and other dried fruits. Sulfur dioxide is also a good reductant. In the presence of water, sulfur dioxide is able to decolorize substances. Specifically, it is a useful reducing bleach for papers and delicate materials such as clothes. SO2 is also a very important compound in winery sanitation.
Sulfur dioxide gas is highly toxic and readily irritates the skin and mucous membranes of the eyes, nose, throat, and lungs.
Sulfur dioxide gas is highly toxic and proper safeguards, including gas monitoring, are deemed critical to industrial health and safety programs.
Sulfuric Acid Production
Pulp & Paper Mills
Food & Beverage
Dried Fruit Production