Accidents material factors

Social Factors. The personalities of co-w orkers and supervisors arc also factors to be considered when evaluating Uie workplace. The liigher Uie employee morale, Uie lower Uie potcnUal for accidents. Another factor is Uie relationship of one job to another, and wheUier Uie job requires Uie coordinating of information, materials, and human effort. 

Unsafe acts are examples of more distant factors from the injury event, where the logical relations are more uncertain. So-called ex-post facto analyses are employed to study whether a causal relationship may exist. In these analyses, we compare statistics on accidents with similar statistics for accident-free situations. The aim is to identify factors which are more common in the accident material than what is expected because of pure chance. In the next step, physical, physiological and psychological theories are brought in to explain the actual causal relationships. 

Chapter 2 discussed the possible influence of atmospheric dispersion on vapor cloud explosion or flash fire effects. Factors such as flammable cloud size, homogeneity, and location are largely determined by the manner of flammable material released and turbulent dispersion into the atmosphere following release. Several models for calculating release and dispersion effects have been developed. Hanna and Drivas (1987) provide clear guidance on model selection for various accident scenarios. 

Measurement of performance. Quality Management requires that measures of performance be established for every activity. These measures include end-of-pipe measurement, such as amounts of material released into the environment or injury rates, and in-process measures of how efficiently you are managing, such as time to review safety improvement proposals or total resources expended on PSM. Each team should be required to identify potential performance measures for the processes they are developing and the activities these processes manage. Many of the end-of-pipe measures will already exist these should be critically examined to ensure that they truly measure performance and are not unduly influenced by other factors. For example, the number of accidents in a fleet of road vehicles is almost directly dependent on the number of miles driven with no improvement in performance, a reduction in miles driven would reduce the number of accidents. 

In general, tlie carriage of hazardous materials does not appear to be a significant cause of, or aggravating factor in, aircraft accidents. However, improperly packed and loaded nitric acid was declared tlie probable cause of a cargo jet crash at Boston in 1973, in which tliree crewmen died,"... 

There are also several possibilities for the temporal distribution of releases. Although some releases, such as those stemming from accidents, are best described as instantaneous release of a total amount of material (kg per event), most releases are described as rates kg/sec (point source), kg/sec-m (line source), kg/sec-m (area source). (Note here that a little dimensional analysis will often indicate whether a factor or constant in a fate model has been inadvertently omitted.) The patterns of rates over time can be quite diverse (see Figure 3). Many releases are more or less continuous and more or less uniform, such as stack emissions from a base-load power plant. Others are intermittent but fairly regular, or at least predictable, as when a coke oven is opened or a chemical vat... 

All of these chemicals pose an inhalation hazard but a toxic dose could also be obtained through skin absorption or ingestion. Factors that were considered when selecting potential candidate chemicals include global production, physical state of the material (i.e., gas, liquid, or solid), chemicals likely to cause major morbidity or mortality, potential to cause public panic and social disruption, chemicals that require special action for public health preparedness, history of previous use by the military, and/or involvement in a significant industrial accident. 

Consequence—The direct, undesirable result of an accidentsequence usually involving a fire, explosion, or release of toxic material. Consequence descriptions may be qualitative or quantitative estimates of the effects of an accident in terms of factors such as health impacts, economic loss, and environmental damage. 

At first glance, this incident does not appear to be process safety related since there was no direct loss of containment however, many factors make it important to review. The material involved in the incident was an undesirable byproduct of an engineered process. AAdien unknown material accumulates in an undesirable location, it often creates a physical hazard. This hazard may directly trigger a loss when it is least expected. Accumulated solids in closed systems may contribute to corrosion, blockage, and physical damage. This accident case study should also be examined in the context of an enclosed system. 

The number of fatalities arising from any identified hazard will depend on several factors, such as the nature of the hazard, the number of people likely to be involved and whether there are any factors mitigating the effects of the hazard. There are many models of varying accuracy and complexity which are available to predict the effects of hazardous events, such as fires, explosions and toxic releases, on people and property. A discussion of them is beyond the scope of this chapter, but for further information the reader is directed to the appropriate chapters of the seminal work by FP Lees Loss Prevention in the Process Industries 2nd Edition (Butterworth Heinemann 1996). Designers should be aware that the effects of major accidents can be felt many kilometres off-site. It is often possible to take a simple view however -lesser and more common (but still serious) events, such as the rupture of a vessel, a small fire, or local release of a harmful material, will clearly have potentially fatal consequences to anyone close by. Fatalities arising from slips, trips, falls and contact with moving machinery are obvious and require no modelling. 

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