Ammonia Risks in Fish Processing

Ammonia is a popular, cost-effective refrigerant in many fish processing plants, both afloat and onshore. Anhydrous (without water) ammonia (NH3) is a colorless, heavier-than-air gas at normal air pressure and temperature, but at pressure it turns into a liquid. It is stored in pressurized containers.

Once released from pressure it turns into an icy vapor that can freeze skin within seconds. When it combines with water it forms ammonium hydroxide, which is a component of lye and thus is also very caustic to skin. It is potentially a flammable gas if heated above 1,560 degrees Fahrenheit and an ammonia/air mix of 16%-25%.

This material is very toxic to aquatic life. Water contaminated with this material must be contained and prevented from being discharged to waterways, sewers or drains.

A striking characteristic of anhydrous ammonia is its high affinity for water. Thirteen hundred gallons of ammonia vapor can dissolve in one gallon of water. If it is not handled carefully it is extremely dangerous.

Due to its high affinity for water, it is attracted to our mucous membranes such as the eyes, nose and lungs. Since the eyes are about 80% water, a shot of ammonia under pressure can quickly cause permanent damage to the eyes. Since fish processing occurs on vessels or shore-side facilities with many workers, a large release of NH3 can also be responsible for a mass casualty.

One positive attribute of ammonia is that its pungent smell is unique. If you smell ammonia, and see a puddle of liquid on the floor, that’s a sign to leave the area immediately and determine the cause of the leak. At a concentration of only 50 ppm, one sniff tells you it’s in the air. A concentration of more than 5,000 ppm will disable a person so that escape is impossible and suffocation results.

Other refrigerants, such as freon, also have their risks but have no odor, making it harder to recognize a leak. Even though NH3 gives you a warning through your nose, “olfactory fatigue” due to small leaks and long exposure can downgrade your ability to smell it over time. Most ammonia releases are due to improper handling and storage equipment failures.

Procedures for Handling NH3

  • NH3 tanks are stored in steel tanks. Low-temperature (less than 20 degrees below zero) refrigerated ammonia system piping must conform to ANSI B31.3 and B31.5 standards.
  • Check that all valves are in good working order, fittings and pipes are in good condition and free of corrosion and wear.
  • Wear personal protective equipment such as rubber gloves to protect hands when operating valves and couplings. To protect eyes, wear unvented, splash-type, well-fitting goggles.
  • Have a self-contained breathing apparatus (SCBA) or NH3-rated mask and protective clothing available which are maintained, and practice donning and using.
  • Operators should carry a 5 to 8 oz. plastic squeeze bottle in a shirt pocket. Change water daily.
  • Permanent ammonia storage locations should have an open container filled with water for emergency use so it can absorb NH3 in an emergency.
  • Eating, drinking and smoking should be prohibited in areas where this material is handled, stored and processed. Workers should wash their hands and face before eating, drinking and smoking. Remove contaminated clothing and protective equipment before entering eating areas.
  • Have drills to increase speed and coordination for an NH3 emergency. Fast, effective response is critical in an NH3 accident.

First Aid

  • No action shall be taken involving any personal risk or without relevant instruction. If it is suspected that fumes are still present, the rescuer should wear an appropriate mask and protective clothing.
  • Water is your friend in an NH3 accident and the best and only first aid treatment for ammonia burns.
  • Contact Poison Control at (800) 222-1222.
  • If there’s ammonia in the eyes, immediately use a squeeze water bottle to flush the eyes. If wearing contacts, remove them and then use more water. Although your eyes will want to stay closed, they must be flushed out to get rid of the ammonia. Flush out the eyes and inside of eyelid for at least 15 minutes. Seek more advanced medical help to prevent permanent damage.
  • If the nose and throat are affected, flood them with water continuously for at least 15 minutes, but take care the victim does not choke.
  • Immediately dampen contaminated clothing, then remove and thoroughly wash the skin. Frozen clothing can be removed using copious amounts of water. Leave burns uncovered—do not cover with clothing or dressings. Do not apply salves, ointments or oils.
  • Get the patient to fresh air. Put the patient in reclining position with head and neck slightly raised. Keep the patient warm to minimize shock.
  • 100% oxygen is useful if ammonia has been inhaled.
  • Anyone overcome or burned by NH3 should be seen by a physician. The damaging effects of ammonia might not be seen for 48 hours or more.

If you smell ammonia, don’t take any chances. Report leaks, ensure good maintenance of equipment and live to freeze fish for another day.  

The Alaska Marine Safety Education Association (AMSEA) has a mission is to reduce injury and death in the marine and freshwater environment through education and training provided by a network of marine safety instructors. The Sitka, Alaska-based organization has been offering marine safety training to commercial fishermen and thousands of other mariners since 1985. More information on marine safety topics can be found at