accidents, there are three main principles. On the one hand, we can reduce the likelihood of primary events; on the other hand, we can prevent the escalation of primary events. Besides, when it is inevitable to prevent domino effect accidents, we can mitigate the consequences of domino effects by preventing the further escalation of accidents. Safety barriers are always used to prevent domino effects and mitigate their consequences. Safety barriers used for protecting chemical industrial areas from domino effects consist of active protection measures; passive protection measures, and procedural and emergency measures. Active protection measures Active protection measures which need power or external activation to trigger the protection action can be used to (i) suppress fire, such as water/foam sprinklers and (ii) isolate process unit using equipment such as emergency shutdown (ESD) systems. An active protection measure usually consists of three elements: (i) a detection system, (ii) a treatment system, and (iii) an actuation system. In order to ensure the performance of active protection measures, all the above three elements should be inactive, otherwise, the protection does not work. Passive protection measures Different from active protection measures, no external activation is needed for passive protection measures. As a result, passive protection measures may be more reliable than active protection measures. Fireproof coating is a commonly-used passive protection measure utilized to isolate chemical vessels from heat radiation induced by external fire. In that case, the time to failure of vessels can be delayed, providing more time for emergency response actions to extinguish the fire. Besides fireproof coating, pressure relief valves are an example of a passive protection measure used to protect pressurized vessels from overpressure. Procedural and emergency measures Procedural actions are these operating procedures that can be used to prevent the escalation of both unintentional and intentional domino effects. Emergency measures include internal emergency actions and external emergency response force. Emergency response procedures in chemical plants play an important role in protecting employees, installations, and other civilians nearby. In terms of domino effects, an emergency response such as firefighting can effectively prevent the escalation of accidents by reducing heat radiation and isolating undamaged vessels, thus preventing domino effects or mitigating their consequences. Since the starting of emergency response actions need a period of time, and emergency resources are typically limited, the optimization of emergency procedures and emergency resource allocation is essential for the prevention of domino effects. References Accidents Causality