Critical hazard, definition

Pilot Plant—Chemical reaction hazards Influence of plant selection on hazards Definition of safe procedures Effects of expected variations in process conditions Definition of critical limits... 

In September 1963, the USAF released MIL-S-38130. This specification broadened the scope of the system safety effort to include aeronautical, missile, space, and electronic systems. This increase of applicable systems and the concept s growth to a formal Mil-Spec were important elements in the growth of system safety during this phase of evolution. Additionally, MIL-S-38130 refined the definitions of hazard analysis. These refinements included system safety analyses system integration safety analyses, system failure mode analyses, and operational safety analyses. These analyses resulted in the same classification of hazards, but the procuring activity was given specific direction to address catastrophic and critical hazards. 

These two definitions reflect two sides of the same situation. In this book, the term critical effect(s) will be used for the hazard/effect considered as being the essential one(s) for the purpose of the risk characterization, e.g., for the establishment of a health-based guidance value, permissible exposure level, or Reference Dose. It should be noted that the critical effect could be a local as well as a systemic effect. It should also be recognized that the critical effect for the establishment of a tolerable exposure level is not necessarily the most severe effect of the chemical substance. For example, although a substance may cause a serious effect such as liver necrosis, the critical effect for the establishment of, e.g., an occupational exposure limit could be a less serious effect such as respiratory tract irritation, because the irritation occurs at a lower exposure level. 

Material Safety Data Sheets, which are now required to be provided by distributors and manufacturers of commercial chemicals, give detailed information on the characteristics of all commonly sold laboratory chemicals. The definitions of explosive, flammable, combustible, and various healthhazards are consistent with those provided by OSHA in CFR 29, Parts Table 3.2 Exemption Limits for a Few Critical Classes of Materials Representing Health Hazards For a Class 4, Hazardous Use Occupancy... 

Integral part of the risk analysis of a critical system is identification and assessment of hazards that significantly contribute to risk (Rausand Hoyland 2004). The hazard analysis generates data required in the next stage of analysis, which lead to description of risk scenarios, definition of safety functions, evaluation of actual risk levels and required risk reduction. Then the technical specification of safety-related functions to be realized by the system architectures considered to select most justified one. 

In the AOP 52 for the calculation of the SSCI it is necessary to know the severity of a hazard. It is categorized in four categories catastrophic, critical, marginal and negligible. These categories are not explicitly defined in the AOP 52 so we guess that these terms can be defined by the user depending on the application, e.g. in the definition of the ALARP approach. This leaves room for interpretations. This holds also true to a lesser extent for the concept of software autonomy of the AOP 52. 

Column 5—RAC or Hazard Category. Enter the risk assessment code (RAC) or hazard category for each failure listed in column 2. An RAC is recommended however, some organizations evaluate FMEA failure only in terms of severity or criticality. In any event, the risk assessment codes or hazard categories must be clearly defined, and their definitions must be included in the FMEA report and/or physically attached to the FMEA worksheets. 

Most industries approach this step in the same way. However, how they differentiate among catastrophic, critical, minor, and negligible hazards may vary. You will need to modify the definitions to fit the particular problem. What is important is that these definitions are determined before work begins. A rule-of-thumb definition for each is the following ... 

A framework has been recently proposed for the performance simulation of Critical Infrastructures (Cl) under seismic hazard, at the regional or urban scale [4]. This framework has been developed within a research project on seismic vulnerability of buildings and lifelines (SYNER-G 2012, [12]), and is thus denoted in the following as SYNER-G framework, or simply framework. It consists of a set of models, that can be jointly used to assess the impact of regional seismic hazard on Cl, in terms for instance of reduced service level, or a community, e.g. in terms of social loss metrics such as displaced population [3].The framework has also been employed to evaluate the probability distribution of a city s resilience [5], adopting the definition in Asprone et al. [1]. 

This is different in case of hazardous situations in the security sense. In contrast to safety-related hazardous situations, an attack might deliberately create those critical circumstances of exposure to hazards. Even when disregarding potential financial losses and reputation decrease for manufacturer and vendor, the impact on system safety cannot be neglected. In that case, the severity of harm to people and environment might be no different from a comparable safety-related incident but the probability of occurrence definitely is not the same. The probability of an unprotected or vulnerable system connected to the internet being scanned or attacked is one [9]. As already explained in the introduction, even though a critical medical system should not be connected to the internet, this is in practice hard to prevent. 

---