Actually death from ammonia is very brutal. The ammonia combines with fluid in the lungs making ammonium hydroxide which is very basic with a high PH. It is like breathing fire and it is brutal. Happened to me as a kid and it was a leaking anhydrous ammonia tank. I was in a car and we drove through it quickly. If we had of been on foot it would have killed us.
Anhydrous ammonia, in liquid or gaseous form, reacts readily with water in the human tissue to form ammonium ions. This process is highly exothermic and causes significant thermal injury to the surrounding tissues. Also, the resultant alkaline solution causes liquefaction necrosis to the tissues through protein denaturation and saponification of fats. Its extraction of water from the human tissues initiates an inflammatory response.
Histopathologic examination of lung tissue after acute exposure to ammonia demonstrates acute pulmonary congestion and edema and desquamation of the bronchial epithelium. There is significant lower airway obstruction resulting from the debris of epithelial cells, red blood cells, and dust cells.