Many hazardous substances are produced, stored and transported in the chemical industry. With the release of these hazardous substances as a result of any uncontrolled development, fire, explosion and toxic spread may occur depending on the nature of the chemical substance. This, in turn, can harm employees, people around, the environment and the economy. In this study, the release of ammonia, which has many uses, has been investigated. Ammonia is a flammable and highly toxic substance. As a result of the accidental releasing of ammonia, a fire event can be prevented by measures such as not keeping the ignition sources in the environment. However, although its ignition is prevented, it can cause harm to the people and environment due to its highly toxic nature. Knowing how much area it affects after spreading will shed light on the measures to be taken to prevent or reduce the damages that may occur. In this study, the toxicity of ammonia was taken into account, and the effect of storage temperature on the size of the toxic area to be formed was investigated. This effect was examined with Areal Locations of Hazardous Atmosphere (ALOHA) and DOW’s Chemical Exposure Index (DOW CEI) methods, and the results obtained with both methods were compared.