Acid burns are characterized by cellular dehydration and protein coagulation denaturation caused by acidic chemicals in contact with the skin, and are accompanied by thermal burns. Acid burns rarely produce blisters, and their wounds are dry, with clearly demarcated edges and mild swelling. Due to protein coagulation, the lesions often do not invade deeper layers, except for hydrofluoric acid. Sulfuric acid, hydrochloric acid, and nitric acid burns are the longest acid burns, and the three acids can cause skin burns in the liquid state and inhalation injuries in the gaseous state. Acid burns are diagnosed by: 1. History of exposure to sulfuric or hydrochloric acid or nitric acid: In particular, you should ask about the type of acid, contact time, first aid for burns and whether there is a history of acid mist inhalation; the local trauma is tested with pH paper showing strong acidity. 2, burn trauma characteristics: sulfuric acid burn trauma is generally black or brown-black; hydrochloric acid burn trauma is yellow-blue; nitric acid burn trauma is yellow or yellow-brown. The trauma surface is soft, moist, lighter color for shallow burns; burned skin is leathery, deep color for deep burns. Acid burn scabs dry, so the subscab infection is generally less. 3, external manifestations: acid burns are often accompanied by upper respiratory tract irritation or laryngeal edema, chest tightness, and even pulmonary edema can occur.