In today's world, accidents are considered as one of the most important risk factors of economic, health, social and even political. Studies have shown that the main cause of most accidents is unsafe human behavior. Obviously, to control these types of behaviors, it is necessary to know their relationship between employees, type and also the factors affecting them. To assess the health risk of exposure to chemical harmful agents, it is necessary to assess the degree of exposure and their risk. The degree of exposure is determined by measuring the factors based on standard methods. The degree of danger is determined according to the type and severity of damage to humans and based on studies. Risk assessment is the center of gravity of occupational safety and health management that focuses on eliminating and minimizing risk. Basically, special techniques have been used for risk assessment and several methods have been presented and developed by researchers for different conditions. The choice of the appropriate method varies according to the studied industries and the objectives of the studies. What if risk methods used in process industries can be What if? Hazop, FMEA and ETA noted that each pursues specific objectives and conducts risk assessment with a specific objective. This study addresses the need for risk assessment in occupational health.