-Farm News photo by Darcy Dougherty Maulsby
Anyone working with anhydrous ammonia should follow every safety precaution, including wearing protective clothing, NH3-rated gloves and ventless goggles. ISU Extension recommends seeking medical attention for any NH3 exposure, even for brief exposures.

As thoughts turn to the upcoming growing season, “safety first” should be top-of-mind when it comes to anhydrous ammonia (NH3).

Under normal temperature and pressure, NH3 is a colorless gas that’s lighter than air. The term “anhydrous” means without water. Because NH3 contains little to no water, it aggressively seeks out moisture, whether in the soil or in your body.

“This chemical is desperately seeking water,” said Dan Neenan, director of the National Education Center for Agricultural Safety (NECAS). “Our bodies are 70% water, so anhydrous ammonia is naturally attracted to our eyes, nose, mouth, sweat glands and genitalia.”

As NH3 seeks out water, ammonia hydroxide is formed, which is extremely caustic and can result in severe burns to the skin, eyes and respiratory tract. As liquid NH3 vaporizes, it has a temperature of -28°F, which can cause severe, frostbite-type burns, said Angie Rieck-Hinz, a field agronomist in north-central Iowa with Iowa State University Extension and Outreach.

Low-dose exposure to NH3 can cause irritation to eyes and skin that may result in burning or coughing.

“Anhydrous pulls moisture out of tissue and can inflict an incredibly painful alkali burn,” Neenan said.

Higher dose exposure and/or longer length of exposure to NH3 can cause severe irritation, permanent damage to tissues (including blindness), and even suffocation due to cell and membrane rupture in the respiratory tract.

“Our lungs are wet, so if you inhale anhydrous ammonia, your lung tissue is burned,” Neenan said. “Any time tissue is burned, it swells. Because our airway has a limited space to take air in, inhaling anhydrous ammonia can quickly result in our airway being closed off.”

Take every precaution when filling NH3 tanks, coupling hoses, transporting tanks and applying NH3, emphasized Rieck-Hinz, who recommends:

1. Always wear NH3-rated gloves and ventless goggles. Gloves should have long cuffs, so the cuffs can be rolled to catch drips. Always be fully clothed in long pants, a long-sleeved shirt, and closed-toe shoes when working with NH3.

2. Never wear contact lenses when working with NH3 or maintaining equipment.

3. If an exposure to NH3 does occur, flush all exposed areas with water for at least 15 minutes. Always carry a personal eyewash bottle with you when working with NH3 and application equipment. This can help buy time to get to your emergency water supply.

4. Do not apply lotions, oils or ointments to skin that has come in contact with NH3, as this may intensify damage.

5. Always have an emergency water supply available when performing equipment maintenance.

6. Keep emergency water supplies clean, filled and accessible at all times.

7. Always use safety chains and a locking hitch pin when pulling nurse tanks.

8. Do not attempt to rescue a victim who has been exposed to a continuous stream of anhydrous ammonia. Any attempt will likely result in additional victims. Rescuers must wear a self-contained breathing apparatus (SCBA) and protective clothing to stay safe.

9. In the event of an incident, immediately call 911, and make sure you are upwind.

10. Seek medical attention for any NH3 exposure, even for brief exposures.