TABLE 2-1 Physical and Chemical Properties of Ammonia


Anhydrous ammonia, ammonia gas

CAS registry number


Molecular formula


Molecular weight


Boiling point


Melting point


Flash point


Explosive limits


Specific gravity

0.639 at 0°C

Vapor pressure

8.5 atm at 20°C


Solubility in water: 47% (0°C), 38% (15°C), 28% (30°C), 18% (50°C); soluble in chloroform and ether

Conversion factors

1 ppm = 0.7 mg/m3; 1 mg/m3 = 1.44 ppm

Abbreviations: NA, not available or not applicable.

Sources: Specific gravity from Czuppon et al. 1992; vapor pressure from Lewis 1993; all other data from Budavari et al. 1989.

Sources of ammonia on submarines include the sanitary system, decomposition of monoethanolamine (a chemical used in the carbon dioxide removal system), and decomposition of insulation blowing agents (Crawl 2003). NRC (1988) listed ammonia as a possible air contaminant on board submarines and reported a concentration of 2 ppm. No information was provided on sampling protocol, location, operations, or duration. No other exposure data were located.


The database to characterize ammonia toxicity is sufficient and includes human and animal data suitable for derivation of exposure guidance levels. Multiple toxicologic reviews are available, including evaluations by the NRC (1966, 1987, 1994, 2002, 2007), the Agency for Toxic Substances and Disease Registry (ATSDR 2004), the American Conference of Governmental Industrial Hygienists (ACGIH 2001), and the National Institute for Occupational Safety and Health (NIOSH 1974). Information from those reviews is summarized in the following paragraphs.

Ammonia is a corrosive, alkaline, irritant gas that produces effects immediately on contact with moist mucous membranes of the eyes, mouth, and respiratory tract. It reacts with moist tissues to form ammonium hydroxide in an exothermic reaction; the thermal and chemical burns resulting from high-concentration exposures are a consequence of the heat of reaction and of the corrosive properties of the alkaline reaction product ammonium hydroxide.

The National Academies of Sciences, Engineering, and Medicine
500 Fifth St. N.W. | Washington, D.C. 20001

Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement