Chemical plants, which are taken place easily the dangerous accidents, generally involve the hazardous chemicals in the production, usage and storage processes. At the beginning of a construction of a plant, we must take into account the protective distance of safe and health in the total layout and residential areas. The effect of the unorganized emission on environment quantity, the harm of the surroundings crowd life due to leakiness and explosion accidents of plants have been calculated, respectively. The protective effect of the calculation on the safe and health protective distance of safe and health is confirmed. The importance and zone in are narrated by some accidents.