Exploring the Contributory Factors of Confined Space Accidents Using Accident Investigation Reports and Semistructured Interviews.

BACKGROUND: The oil and gas industry is one of the riskiest industries for confined space injuries. This study aimed to understand an overall picture of the causal factors of confined space accidents through analyzing accident reports and the use of a qualitative approach. METHODS: Twenty-one fatal occupational accidents were analyzed according to the Human Factors Analysis and Classification System approach. Furthermore, thirty-three semistructured interviews were conducted with employees in different roles to capture their experiences regarding the contributory factors. The content analyses of the interview transcripts were conducted using MAXQDA software. RESULTS: Based on accident reports, the largest proportions of causal factors (77%) were attributed to the organizational and supervisory levels, with the predominant influence of the organizational process. We identified 25 contributory factors in confined space accidents that were causal factors outside of the original Human Factors Analysis and Classification System framework. Therefore, modifications were made to deal with factors outside the organization and newly explored causal factors at the organizational level. External Influences as the fifth level considered contributory factors beyond the organization including Laws, Regulations and Standards, Government Policies, Political Influences, and Economic Status categories. Moreover, Contracting/Contract Management and Emergency Management were two extra categories identified at the organizational level. CONCLUSIONS: Preventing confined space accidents requires addressing issues from the organizational to operator level and external influences beyond the organization. The recommended modifications provide a basis for accident investigation and risk analysis, which may be applicable across a broad range of industries and accident types.

Cardiac strain comparison between workers with normal weight and overweight in the hot humid weather of the Persian Gulf region.

BACKGROUND: In the hot weather, overweight and obesity are considered as significant risk factors for the incidence of cardiac strain in workers. This study is aimed at comparing the cardiac strain among overweight and normal-weighted workers, in the hot, humid conditions of the south of Iran. MATERIALS AND METHODS: This cross-sectional study was conducted on 71 workers in the south of Iran, in the summer of 2010. The heart rate was measured at rest and at actual work. Cardiac strain based on the working heart rate (WHR), the relative cardiac cost (RCC), the net cardiac cost (NCC), the load relative cardiovascular (CVL), and heart rate reduction were analyzed in 35 normal weight people (BMI <25) and 36 people who were overweight (BMI >25), using descriptive statistics and t- tests. RESULTS: In 42% of the total workers, the body mass index was more than 25. The average temperature of the two groups was not significantly different. The mean WHR in these two groups was 101 ± 20.3 and 112 ± 18.9, respectively (P = 0.026). Percentages that exceeded the acceptable limits in parameters of NCC, RCC, WHR, CVL, and the Brouha index, were significantly higher in overweight people than those in people with normal weight. CONCLUSIONS: Based on the study results, the severity of cardiac strain was higher in overweight workers when compared with normal weight workers. Hence, in order to decrease the cardiac strain, selecting overweight individuals for these jobs should be avoided, as also some vital intervention for losing weight, such as, nutrition education and encouraging them to increase their physical activity, should be implemented.

Control of exposure to hexavalent chromium and ozone in gas metal arc welding of stainless steels by use of a secondary shield gas.

Previous work has demonstrated that the shield gas composition in gas metal arc welding can have a considerable effect on hexavalent chromium [Cr(VI)] concentration in the fume and on ozone concentrations near the arc. Normally a single shield gas is used. This paper describes a double shroud torch that allows used of concentric shield gases of different compositions. A solid stainless steel wire was used for welding. The double shroud torch used secondary shield gases containing small amounts of the reducing agents NO and C2H4. The Cr(VI) concentration in the fume and ozone concentration at a fixed point relative to the arc were measured and compared with results when using a single shield gas. Use of the reducing agents in secondary shielding using the double shroud torch was found to offer advantages for ozone concentration reduction compared with use in a conventional torch, but this was not found to be an advantage for reducing Cr(VI) concentrations.

Control of occupational exposure to hexavalent chromium and ozone in tubular wire arc-welding processes by replacement of potassium by lithium or by addition of zinc.

Hexavalent chromium [Cr(VI)] and ozone are produced in many arc-welding processes. Cr(VI) is formed when welding with chromium-containing alloys and is a suspected carcinogen. Ozone is formed by the action of ultraviolet light from the arc on oxygen and can cause severe irritation to the eyes and mucous membranes. Previous work has demonstrated that reduction of sodium and potassium in manual metal arc-welding electrodes leads to substantial reductions in Cr(VI) concentrations in the fume as well as a reduction in the fume formation rate. In this paper replacement of potassium by lithium in a tubular wire welding electrode (self-shielding flux-cored) is shown to give reductions in Cr(VI) concentrations and fume formation rates. Previous work has also demonstrated that use of a tubular wire (metal cored) containing 1% zinc can, under certain conditions, result in a reduction in Cr(VI) formation rate and in ozone concentration near the arc but with a rise in the total fume formation rate. The effects of different shield gases and different levels of zinc are examined. An experimental chromium-containing tubular wire with 1% zinc was used with the following shield gases: argon, Argoshield 5, Argoshield 20, Helishield 101, Ar + 2% CO2, Ar + 5% CO2, Ar + 1% O2 and Ar + 2% O2. The wire gave > 98% reduction in Cr(VI) formation rate compared to the control wire provided the shield gas contained no oxygen. When the shield gas did contain oxygen, 1% zinc enhanced Cr(VI) formation rate, resulting in more than double the rates measured when welding with the control wire. Experiments with zinc concentrations, from 0.018 to 0.9% using Helishield 101, gave results indicating that there is an optimum zinc concentration from the point of view of Cr(VI) reduction. Implications of the use of lithium or zinc on the overall exposure risk are discussed.