The aim of this paper is to determine production and development of chemical has indeed greatly improved the living conditions of people. However, the intrinsic hazardous properties of chemicals pose a great threat to human survival and environment. Especially, the leakage of liquefied ammonia can cause both explosion and poisoning which bring death and injury to people and animals, loss of property and destroy of environment. Although much effort has be made to solve the safety problem of chemicals production and operations from the whole lifecycle, chemical accidents. The scenario is assumed that the liquefied ammonia leakage accident took place in San Antonio Texas and the residents are usually living in one-story building as a result of the farming and remote area