# Modelling a Safety Management System Using System Dynamics at the Bhopal Incident
## 1 Introduction  
In 1984, the well-known Bhopal disaster involved the chemical plant of the American multinational Union Carbide, specialized in production of pesticides. The explosion of a methyl isocyanate storage tank inside the plant caused the death of about 3000 people and poisoned tens of thousands more. The incident started a long process of research and investigation concerning the causes and effects [1], which led to the consideration that the accident could have been be avoided. In fact, a lack of maintenance and precautions in safety operations was detected. Moreover, according to these studies the large multinational Union Carbide had little concern for safety in an emerging country where the technology used was untested and faulty. Though a rare incident, Bhopal was not a random event; rather, it was predictable, and the causes were accessible and the events potentially avoidable [2].  
The Bhopal incident is one of the most important examples of the lack of safety due to no maintenance policies, no human continuous training and no plan investments. For these reasons, the Bhopal accident is well suited to highlight the impact that maintenance and the human factor have on the safety management system.  
In particular, if the maintenance was efficient, the extent of the accident would have been more contained [3].  
The Bhopal disaster has led to regulations and awareness of process safety-related activities worldwide. The whole scientific community has focused on the causes and consequences of the disaster, with particular attention to the topic of maintenance and safety [4].  
These studies have developed a new safety culture [5] with different proposed approaches. [PERSON] et al. proposed a Bayesian approach [6] while [PERSON] [7] managed safety by using a different methodological approach based on system dynamics (SD).  
According to [PERSON]'s paradox [8], \"the results of quantitative system dynamic study are qualitative insights\", this paper aims to highlight, by using a quantitative model based on Bhopal accident data, that the technical, organizational and human factors that could have been managed effectively with a safety management system (SMS).  
System dynamics are used to highlight the interrelations among the factors that mainly affect maintenance and its effects on safety. This leads to consideration of the impact that maintenance and human factors could have on the safety of a high-risk plant, thus being key factors in an appropriate management system.  
It is true that one of the key points implemented in industry 4.0 is how to reduce environmental pollution, as shown by [PERSON] et al. in a recent paper [9], but also to increase safety by receiving real time inputs about hotspots of the system; for example, in a high-risk industrial sector such as the petrochemical one, the industry 4.0 approach is used to monitor big data from a variety of sources, as highlighted by [PERSON] et al. [10].  
Literature, as well as _Process Safety and Environmental Protection_ (PSEP), tries to support the integration among concepts and industry 4.0 technologies for sustainable production systems [11]. Undoubtedly, receiving data in real time allows the optimization of the enterprise resource planning (ERP) [12].  
The paper is organized as follows: Section 2 presents the methodological approach, in Section 3 the model is analyzed through a real case study concerning the Bhopal incident and results are analyzed in Section 4. A discussion about how industry 4.0 could reduce system failure probability is presented in Section 5. Finally, conclusion of the research is summarized in Section 6.