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Anhydrous ammonia

Anhydrous (“without water”) ammonia (NH3) is a chemical covered under Part 36 – Chemical and Biological Substances of the Manitoba Workplace Safety and Health Regulation. It can take both gas and liquid forms, is colourless and has a suffocating, pungent odour.

NH3 is hygroscopic, which means that it seeks water from the nearest available source, including any moisture found in the human body. When combined with water, a corrosive substance is formed.

Low concentrations (<25 parts per million or ppm) of NH3 will irritate the eyes, skin and respiratory tract and produce temporary symptoms such as coughing and wheezing (through inhalation).

Exposure to higher concentrations (>35 ppm) of NH3 for any length of time is extremely dangerous and can result in immediate and permanent severe chemical burns to the eyes, skin and respiratory tract. NH3 burns can cause pulmonary edema, a painful condition that causes respiratory failure, cardiac arrest and death.

Ammonia in the workplace

Appropriate actions should be taken to eliminate or reduce the risk of exposure to ammonia in the workplace.

Workplaces that use ammonia as a refrigerant are most commonly associated with potential ammonia exposures, such as food and beverage manufacturing, processing facilities, ice rinks, cold storage plants and ice manufacturing plants.

Ammonia exposure can also occur during other workplace activities that use compressed ammonia gas, such as blueprinting, die hardening, cleaning products manufacturing and when workers repair or maintain ammonia systems.

Other workplaces subject to ammonia exposure are those that use liquid ammonia, which can include microorganism growers, wastewater treatment plants and agricultural fertilizer manufacturers. Liquid ammonia is also used directly in agricultural fields as a fertilizer.

The dangers of ammonia

Breathing ammonia gas can be fatal. The level of danger depends on the ammonia concentration and length of exposure. In low concentrations, exposure to ammonia gas causes irritation to the eyes and the respiratory system, and liquefied or pressurized ammonia can cause chemical and freezing burns to the skin and eyes. In high concentrations, ammonia gas can be fatal within a few breaths.

Taking precautions to prevent exposure

It is critical to practice appropriate safety protocols when working with ammonia. The following are some procedures to consider:

  • When possible, eliminate or substitute ammonia for a safer material.
  • Implement engineering controls that generate less ammonia and improve ventilation systems to ensure current threshold limit values are followed.
  • Consider installing barriers to help prevent gas from leaking into other areas of the workplace.
  • Ensure a large supply of water (20-25 litres) is accessible for workers to flush eyes in case of emergency.
  • Train workers on ammonia exposure dangers and warning signs, safe work procedures and manufacturer and dealer’s instructions.
  • Train workers to use personal protective equipment (PPE) and ensure the correct equipment is supplied and available in good working order.
  • Develop and implement an exposure control plan. An effective plan must include purpose and responsibilities, a risk assessment, controls, education, training, written safe work procedures, a Safety Data Sheet (SDS), washing or decontamination facilities and documentation.

Protection against ammonia in the workplace

To protect workers, employers should change the material to eliminate or substitute NH3 for a safer process or material. Where possible, implement engineering controls that generate less ammonia and improve ventilation systems to ensure current threshold limit values are followed. Employers should also ensure Transport Canada regulations for NH3 are followed when attempting to transport the chemical and train workers on ammonia exposure dangers, warning signs, safe work procedures, manufacturer and input dealer’s instructions and personal protective equipment.

Legislation

Manitoba’s Workplace Safety and Health Act and associated regulations protect the safety and health of workers in Manitoba. The regulation section associated with this safety topic is linked below.

Part 35 Workplace Hazardous Products Information Systems Manitoba Workplace Safety and Health Act and Regulation
Part 36 Chemical and Biological Substances Manitoba Workplace Safety and Health Act and Regulation

Related links

Hazards and exposures topic list