Anhydrous ammonia is a colorless gas at room temperature with a boiling point of -28 degrees F and is typically shipped as a liquid under pressure. Ammonia has the chemical formula NH3 and a molecular weight of 17.03 and is characterized as having a very sharp, pungent odor.

Anhydrous ammonia is used in the manufacture of nitric acid, explosives, synthetic fibers and fertilizers. It is also extensively used in the food manufacturing industry as a refrigerant.

Ammonia / Ammonia Refrigeration

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What are the health hazards of ammonia?

The following exposure limits apply to occupational exposure to ammonia:

  • The OSH Permissible Exposure Limit (PEL) for ammonia in air is 50 parts per million (ppm) as an 8 hour time-weighted average (8 hr TWA).

  • The NIOSH Immediately Dangerous to Life and Health (IDLH) concentration in air is 300 ppm.

The principal routes by which employees can be exposed to anhydrous ammonia are by inhalation and by contact with skin and eyes. Because the lower limit of detection by humans is 53 ppm, continued employee exposure at levels where it can be detected by smell could result in employee exposure above the OSH PEL. Inhalation of concentrated ammonia vapor can result in pulmonary edema and asphyxia which can result in death if prompt treatment is not provided. In addition, exposure of unprotected skin to anhydrous ammonia can result in frostbite.

What are the physical hazards of ammonia?

Ammonia can form explosive mixtures in air. The lower explosive limit (LEL) for ammonia in air is 15 percent and the upper explosive limit (UEL) is 28 percent.

What can I do to protect myself?

Employees who work regularly with anhydrous ammonia and are subject to overexposure either to the liquid or the vapor must be provided by their employer with the appropriate personal protective equipment including, but not limited to, goggles, impervious clothing, gloves and respiratory protection. At concentrations of ammonia above 10 percent, employers should provide an eyewash and/or suitable quick drench facilities in work areas where ammonia is used in the event of a spill or release that results in direct contact with the eyes or skin.

Employers are required to develop and implement a written hazard communication program that details how employees will be trained about the hazards of anhydrous ammonia and provide them with access to safety data sheets for this and any other hazardous chemicals used in their work areas. Where the amount of anhydrous ammonia used in a process reaches or exceeds 10,000 pounds, or the quantity of ammonia solutions having a concentration greater than 44 percent by weight of ammonia reaches or exceeds 15,000 pounds, the employer must also develop a written process safety management plan for which the purpose is to prevent or minimize the consequences of a catastrophic release of ammonia from the process.

What resources are available to assist employers?

Safety and Health Programs

These example programs and assessments for hazard communication, job hazard analysis, respiratory protection programs, and personal protective equipment can be downloaded and customized to fit an individual workplace.

Training and Outreach Services

Presentations on hazard communication, respiratory protection, and personal protective equipment can be downloaded and customized to assist employers in conducting employee training at their workplaces. 

In addition, the education, training and technical assistance bureau provides free online safety and health training and outreach services (i.e., speaker's bureau requests, safety booths) upon request. 

The NCDOL Library offers free safety and health videos (including streaming video services) and related research assistance on consensus standards (i.e., ANSI, NFPA, NEC).

A-Z Safety and Health Topics

Additional resource information can be found on the A-Z topics pages for process safety management, respiratory protection, hazard communication, HAZWOPER, eyewash stations and emergency showers and personal protective equipment

Consultation Services

The consultative services bureau provides free and confidential onsite consultation regarding worksite safety and health hazards.


Which standards apply?

OSH has adopted the following standards which are applicable to ammonia in North Carolina. Note: Please also check the standards information and activity webpage to see if there has been any recent or upcoming regulatory activity on this topic. 

General Industry

Other Applicable Standards

In addition, the Which OSHA Standards Apply webpage can help identify other standards that may be applicable to your worksite.

Where can I learn more?

Industry Guides

Technical Assistance

If you would like to receive interpretive guidance on this or any other OSH standard or topic, you can submit your questions using the Ask OSH web form, by e-mail to or by calling 919-707-7876.