Lagging metrics

The description of less severe incidents (i.e., below the threshold for inclusion in a lagging metric), or unsafe conditions that activated one or more layers of protection. Although these events are actual events (i.e., a lagging metric), they are generally considered to be a good indicator of conditions that could ultimately lead to a severe incident. 

To provide guidelines and examples of effective practices for the development and use of process safety leading and lagging metrics ... 

Center for Chemical Process Safety, Guidelines for Process Safety in Batch Reaction Systems, American Institute of Chemical Engineers, New York, 1999 Center for Chemical Process Safety, Process Safety Leading and Lagging Metrics, American Institute of Chemical Engineers, New York, 2007 Reason, J., The contribution of latent human failures to the breakdown of complex systems. Philosophical Transactions of the Royal Society (London), series B. 327 475-84(1990)... 

Lagging Metrics—process safety incidents that meet the threshold of severity and shouid be reported as part of the process safety metric Near-Miss Incidents—incidents that did not meet the definition of process safety incident metric... 

Criteria for lagging metrics should be set below the level that describes catastrophic events. While it is important to capture those catastrophic incidents, it is equally, if not even more, valuable to define such metrics to capture less-severe incidents, including the failure of the process safety elements, which protect against or limit the consequences of a major incident (HSE, 2006). Lagging metrics that represent failures of a less-severe nature are valuable in identifying potential hazards before a catastrophic event occurs. Such information helps management understand issues at an early stage when they may be more easily addressed. 

Near-miss metrics include actual process safety incidents that do not meet the threshold defining a lagging metric as well as system failures that could have, but did not, lead to an incident such as an instrumentation failure or vessel corrosion. Near misses are often less obvious than accidents and are defined as having little if any immediate impact on individuals, processes, or the environment. Despite their limited impact, near misses provide insight into accidents that could happen. 

The ultimate goal of the process safety system is to prevent process safety incidents. The Center for Chemical Process Safety s Process Safety Leading and Lagging Metrics Report (CCPS, 2007b) defines a consensus from several chemical and allied processing industries for definitions of process safety incidents and process safety near misses. If an organization adopts these definitions, a... 

Common process safety metrics, such as the number of process safety incidents, can provide a basis for such comparisons among facilities within an organization, among different companies within an industry, and even among different industries. The major goal of CCPS s Process Safety Leading and Lagging Metrics is to create such common definitions. 

Center for Chemieal Proeess Safety, Process Safety Leading and Lagging Metrics, American Institute of Chemical Engineers, New York, 2007... 

As discussed earlier in the book, common metrics are necessary for companies to compare their performance with other companies and overall industry performance. Consensus process safety metrics are only beginning to be adopted within the processing industries. Consensus process safety metrics are being developed, such as those recommended in the CCPS publication Process Safety Leading and Lagging Metrics. Pressure from within the industries and from outside stakeholders will encourage the broader acceptance of current consensus metrics as well as the development of more such metrics. Such metrics will be used not only by companies and industries, but especially by outside parties to evaluate industry-wide performance or the performance of individual companies against the industry as a whole. 

In 2008 the Center for Chemical Process Safety (CCPS) published Process Safety Leading and Lagging Metrics—You Don t Improve What You Don t Measure. 

Three types of process safety performance metrics are described in the document and the text on their selection and application is extensive. Reference is made to lagging metrics leading metrics, and near miss and other internal lagging metrics. Note that near misses are a metric separate from lagging indicators. This is the only publication found that makes that disfinction. As will be seen, there is a purpose for doing so in the CCPS document. The metrics pertain only to chemical process incidents and near misses, to the exclusion of types of incidents that are not process related. 

There is a separate section in the CCPS document on Near Miss Reporting and Other Lagging Metrics. This is said about near misses. 

Since a near miss is an actual event or discovery of a potentially unsafe situation, this metric could be defined as a lagging metric. A large number or increasing trend in such events could be viewed as an indicator of a higher potential for a more significant event therefore, many companies use Near Miss metrics as a surrogate for a Leading metric. 

The immediately preceding quotation is the definition of a leading indicator in the Process Safety Leading and Lagging Metrics paper. 

Process safety leading and lagging metrics Center for Chemical Process Safety 2009 www.aiche.org/ccps... 

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