Mississippi State Department of Health

Fact Sheet: Anhydrous Ammonia


Anhydrous ammonia is used widely and in large quantities for a variety of purposes. More than 80% of the ammonia produced in the United States is used for agricultural purposes; less than 2% is used for refrigeration. The substance is stored and used at agricultural retailers and facilities with ammonia refrigeration systems. Anhydrous ammonia also is a key ingredient in the illegal production of methamphetamines. Illegal drug makers often steal anhydrous ammonia from areas where it is stored or used.

Anhydrous ammonia is stored as a liquid under pressure. When released to the environment, though, it becomes a toxic gas. Liquid anhydrous ammonia expands 850 times when released to ambient air and can form large vapor clouds. It may aerosolize and behave as a dense gas, even though it is normally lighter than air. Anhydrous ammonia may also cause water vapor to condense in the air forming a visible white cloud. Therefore, when anhydrous ammonia is released to the air, it may travel along the ground in a cloud instead of immediately rising into the air and dispensing. This dense gas behavior may increase the potential for exposure of workers, responders and the general public.

Risks and Safety
Anhydrous ammonia is toxic and can be a health hazard if safe handling procedures are not followed. Effects of inhalation of anhydrous ammonia range from lung irritation to severe respiratory injuries, with possible death at higher concentrations. Anhydrous ammonia is also corrosive and can burn the skin and eyes. When stored as a liquid, it has a boiling point of minus 28 degrees Fahrenheit and can cause freezing burns. Special precautions must be taken when handling anhydrous ammonia to avoid exposure of workers and others. People who work with this chemical on a daily basis, such as the refrigeration industry, are at risk of exposure and must be cautious.

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