During the development of Korea's industry, leakage accidents of hazardous substances are bound to occur due to non-compliance with safety standards, facility defects, transportation vehicles, and natural disasters. It was confirmed that workplaces handling hazardous and dangerous substances are increasing, and it was The conclusion that can be drawn through the study is that if a target gas such as a hazardous substance leaks, it can be confirmed that a fatal accident can occur not only to all subcontractors working in the process, but also to nearby residents depending on the scope of influence. Summarizing the results of the simulation data, in the case of leakage of hazardous substances in a small space, the time to reach not only the concentration of interest but also the immediate death concentration is very short. Even in a large space, if there is only operating pressure and sufficient capacity, the time to reach the concentration that exceeds the concentration of interest and leads to death is less than 30 seconds, and can be reached within a few seconds. Large-capacity facilities will also have a longer leakage duration, so it can be confirmed that the concentration of interest is easily reached even if it is outdoors. Through this study, more empirical studies and studies in various situations are conducted to establish new regulations, so that workers can go home safely and have a warm dinner with their families.