Accident-concentration analysis

Accident-concentration analysis was first developed within traffic-safety research and was here denoted black-spot analysis . By analysing the geographical distribution of traffic accidents, instances of poor design of the road network could be identified. The accident black spots were the geographical locations (e.g. crossings), where many of the accidents occurred. The remedial actions were channelled to these locations. 

The application of accident-concentration analysis is not meaningful for small data sets. There must be at least in the region of 50 accident cases. Useful types of data in accident-concentration analysis are location, activity, equipment, accident type, type of injury and part of body affected. The analysis is facilitated if some of the data is coded (i.e. presented on a nominal scale of measurement), especially if large quantities of data are handled. The coding should, however, not be done at the cost of the details in the information. The free-text description of the sequence of events should always be available. 

In an accident-concentration analysis, the analyst must be familiar with 

2 Identify cells with a high number of cases. 

3 Repeat the procedure for cells with a high number of cases until meaningful accident concentrations have been identified. At the detailed level, it is often necessary to study the description of the sequence of events in the original reports and to arrange these in new, meaningful groups. 

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Figure 15.6 shows another example from offshore yards. Accident-concentration analysis of this type helps prioritise remedial actions. Detailed... 

Figure 15.6 Results of an accident-concentration analysis of construction work in an offshore project. The results were used in planning the SHE activities in a subsequent project.

Accident-concentration analysis is dependent on the analyst s analytic skills and knowledge about the studied industrial system. There are today statistical tools such as FAC (Factorial Analysis of Correspondence) and HAC (Flierarchical Ascendant Classification) that may help identify accident concentrations and thus make the analysis more objective. Such analyses do not replace but are complementary to the more intuitive analysis made by SFIE experts. In a study of accidents among female automobile assembly workers, Laflamme (1996) identified four such concentrations by applying FAC and HAC ... 

In the Coarse analysis, we especially want to focus on hazards that may result in serious consequences. It is also recommended to focus on hazards that may result in many (but less severe) accidents. Consult the accident statistics for the actual plant or similar plants for accident concentrations. Results are documented on a record sheet according to Table 22.3. 

A joint analysis of the results from different departments with similar types of production will support in the identification of potential accident concentrations. 

Norskoil develops experience checklists for hand-over to the EPC contractor. They are based on accident-concentration analyses, where accident data from existing installations have been used. An accident database is employed in the analysis. Norskoil s project team reviews the findings together with operations personnel from these two platforms. Jointly, they come up with recommendations on how to prevent the identified accident concentrations by measures in design. 

Similar accidents have been mentioned with H2S2O8 peroxydisulphuric acid. If the peroxide/alcohol mixtures are made with concentrated hydrogen peroxide, they either detonate or combust spontaneously. Analysis shows that the selfignition temperature of 2-propanol is much lower when hydrogen peroxide is present. 

Two characteristic times can be identified in the analysis of accidents. For the most corrosive products, penetration starts after the first 10 s. This penetration is nearly total after 1 min. The symptoms and their occurrence depend on the seriousness and reversibility of the corrosive or irritating product and its concentration. 

Concern over dioxins originally arose over one particular dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). This was found to produce clinical effects (chloracne) in workers exposed to it through industrial accidents.35 It is also toxic to some species of laboratory animals. A few PCBs have been shown in experimental systems to exert a number of toxic responses similar to those observed for TCDD. In consequence, the total concentrations of both dioxins and PCBs in environmental media, including food, are now commonly determined as part of the same chemical analysis, and each cannot be discussed now without reference to the other. 

Individuals exposed through industrial accidents or environmental contamination. Very extensive residential contamination by 2,3,7,8-TCDD occurred in Seveso, Italy, when a 2,4,5-TCP reactor exploded in 1976 (Mocarelli et al. 1991). The contaminated area was divided into three zones based on the concentration of 2,3,7,8-TCDD in the soil. Families in zone A, the most heavily contaminated area based on soil 2,3,7,8-TCDD levels, were evacuated within 20 days of the explosion and measures were taken to minimize exposure of residents in nearby zones. A recent analysis of 19 blood samples from residents of zone A, which were collected and stored shortly after the accident, showed serum lipid levels of 2,3,7,8-TCDD that ranged from 828 to 56,000 ppt. These serum lipid levels are among the highest ever reported for humans (Mocarelli et al. 1991). 

DEHP is lipophilic and tends to migrate into adipose deposits. Since it is cleared from these deposits slowly, analysis of fat tissues probably provides the best test for previous exposure to this plasticizer. Analysis of human abdominal adipose tissues from accident victims indicated that DEHP was present in these tissues at a concentration of 0.3-1.0 ppm (Mes et al. 1974). DEHP was also identified in 48% of the adipose tissue specimens from cadavers autopsied in 1982 as part of the Human Adipose Tissue Survey from the National Human Monitoring Program (EPA 1989b). Neither study contained data on DEHP exposure history of the subjects, however, and there is no information regarding correlation of adipose tissue concentrations with DEHP exposure concentration and duration. 

Besides the analysis of nuclear fuel and of radioactive waste materials, the determination of contamination and enrichment of selected radioactive nuclides, e.g., which is one of the most important environmental indicators of nuclear accidents, Se, Tc, Np, Pu, °Pu and "Am at ultratrace concentration levels, is useful for environmental monitoring of fallout from nuclear weapons testing, nuclear power plants or nuclear accidents. ". Selected application fields for the determination of natural and artificial long-lived radionuclides (LLR) and radionuclides investigated by mass spectrometric techniques are summarized in Tables 9.36 and 9.37, respectively. 

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