MSHA - Ammonia (NH3) - Health Alert

"Exposure to high levels of ammonia can cause serious health effects involving the eyes, lungs, and skin. Miners working with or around ammonia should take caution. Use engineering controls, such as ventilation, and if respirators are in use, ensure that an ammonia-specific filter cartridge is used..."

https://www.msha.gov/sites/default/files/Alerts-Hazards/Health%20Alert_Ammonia.pdf