دو ماهنامه سلامت کار ایران
سال دهم شماره 1 (فروردین و اردیبهشت 1392)

Human factors are significant factors causing car accident s. The driver when noticed by brake lights will pay attention to the danger and react appropriately. An appropriate reaction time can prevent car accidents. The aim of this study was to assess driver's reaction time to dynamic flashing and standard brake lights using a driving simulator. This experimental study was done on 46 volunteer drivers (10 female, 36 male). Participants drove for an hour under day and night conditions on a driving simulator system with standard brake lights and dynamic flashing brake lights. Results showed that as the age of drivers increased one year, the brake reaction time was decreased 11.585 ms. Women had slower brake reaction time than men. There was no significant relationship between driving condition and brake reaction time. The time elapsed since taking driving license has not any significant effect on reaction time. In general, this research showed that using dynamic flashing brake light with a flashing frequency of 7 Hz reduced the brake reaction time significantly.

Formaldehyde (H2C = O), is a member of aldehyde family with the simplest organic molecules, used in various industries. The aim of this experimental study was to investigate the detrimental effects of formaldehyde on testicular tissue and sperm quality in mice. Thirty six mature male NMRI mice were randomly divided into three equal groups (n=12). Group F1 (low concentration) and group F2(high concentration) were exposed to formaldehyde vapour corresponding to inhalation chamber concentration of 10 and 20 ppm respectively for 10days(8 hours per day),while the third group received fresh air as the control group. Following exposure, half of the experimental animals in each group (n=6), were sacrificed after 24 h to detect short-term effects and the other animals (n=6) after 35 days to detect long term effects,, the epididymal tissues were taken for sperm analysis as well as testes removed for histological examination. The results of long-term effects study showed that the epididymal sperm concentration and the percentage of progressive sperm motility significantly decreased (P < 0/01), the abnormal sperm rate significantly increased(P < 0/01) in both experimental groups compared to the control group. Testicular histology analysis, 35days after exposure showed that formaldehyde induces alterations such as epithelial vacuolization and seminiferous tubles atrophy. The inhaled formaldehyde can destroy testicular tissue and decrease sperm quality.

Noise is considered as a common occupational health hazard in a wide range of occupational settings including oil and gas industries and related companies. This research aimed to assess the environmental noise and personal exposure in a petrochemical plant. First, environmental noise measurement was performed as recommended by ISO9612 (1997) and next, short-term dosimetery was conducted for a 2-hour sampling period, during which individuals worked at Site. Then 4-hour dose was calculated based on 2-hour dose, and finally 8-hour equivalent level was estimated by 4-hour dose and equivalent sound levels were measured in the resting rooms. The results showed that 8.8% of total stations measured have been in the danger zone and more than 74% of them were in the caution zone. It was found that the Air unit has the higher sound pressure level than the other units and Compression part of Air unit with a mean of 93.28 dB A and the peak level of 101.2 dB A has the highest noise level recorded. According to personal noise dosimetry results, the 8-hour equivalent level in Water, Air and Powerhouse was 81.7, 89.2. and 82.5. dB A respectively. The results of environmental and personal noise monitoring suggested that Air unit has the most noise pollution in the petrochemical plant. Therefore, it is necessary to identify the dominant sources of noise and prioritize different units to control the noise pollution of the industry.

Job stress at workplaces is an effective factor on job satisfaction, turnover and task performance. This research was administered with the aim of investigating the relationship between job stress with turnover and task performance considering the mediating role of job satisfaction. The research method was descriptive which administered in the form of co-relational. Research statistical population was the employees of a public sector organization, among them, 187 persons were selected via simple random sampling. Research instruments consisted of: Babakas et al ’ s (2009) turnover, task performance and job stress questionnaires, and Spector ’ s (1985) job satisfaction questionnaire. Data were analyzed using Structure Equation Modeling (SEM). Results revealed that: 1. There are negative significant relationship between job stress with job satisfaction and task performance, and positive significant relationship with turnover (P<0.01). 2. Job satisfaction has negative significant relationship with turnover, but it has positive significant relationship with task performance. 3. Job satisfaction was partial mediator variable on the relationships between job stress with turnover and task performance. The results of this research showed that to control the effects of stress on turnover and task performance, organizations must concentrate on the stress management training and reinforcement the job satisfaction.

To date, there is not enough information about the toxic effects of dolomite. The purpose of this study was to assess the extent to which digging and excavating workers involved in constructing a dam in Fars province were exposed to dolomite dust and to evaluate the possible effects of this exposure on the prevalence of respiratory symptoms, functional impairments and radiographic abnormalities of the lungs. This cross sectional study was carried out at the constructing site of a dam in Shiraz, south of Iran. The study population consisted of thirty nine male workers with current exposure to dolomite dust and 40 healthy male unexposed employees. To determine the prevalence of respiratory symptoms, respiratory symptoms questionnaire were used. Personal dust samplers were used to assess the exposure concentrations. Additionally, subjects underwent lung function tests and chest X-ray. Atmospheric concentrations of dolomite dust exceeded current permissible levels. Exposed workers had significantly higher prevalence rates of respiratory symptoms than their referent counterparts (P<0.05). Similarly, decrements were noted in most parameters of pulmonary functions of exposed workers, although the difference was only significant for FEV1/FVC ratio (P<0.05). No significant differences were noted between exposed and referent subjects as far as their chest radiographs were concerned. The findings of this study indicate that medium term exposure to very high concentration of dolomite dust is likely to be associated with respiratory symptoms.

Carbon monoxide (CO) is a highly toxic, colorless, and odorless gas with a density close to the air, which is produced by natural processes and anthropogenic sources and is well known for its potential harmful and poisonous effects on humans. Inhalation of carbon monoxide gas can impair the heart and central nervous system. Diatomite supported nano copper oxide catalyst was used to investigate the catalytic oxidation of carbon monoxide. In this study, it was shown that how a low cost diatomaceous earth can be used as catalyst support. The required amount of copper oxide nanoparticles placed into 200 ml deionized water to prepare different concentrations (1wt%, 2wt%, 3wt%, 4 wt% and 5wt%) of nanoparticle, next the suspension liquid stirred for 30 min at pH of 7 at room temperature, and then 100g diatomite was added to the above solution. The nano CuO coating was implemented under sonication conditions in ultra sound bath for 20 min at room temperature, and gently stirring was then carried out for 2h.The prepared catalysts were characterized by Brunauer-Emmett-Teller (BET) surface area, scanning electron microscopy (SEM), X-ray diffraction (XRD) and porosimetry. The influence of reaction temperature, CuO loading, and calcination temperature on the catalytic activity of copper oxide nanoparticle supported on diatomite have been studied. Their catalytic behavior for CO oxidation was studied at different conditions in a tubular reactor packed with catalyst using a multi-component NDIR gas analyzer (Delta 1600 S-IV). The catalytic behavior of catalyst was dependent on the nano copper oxide content, reaction temperature, retention time and the particle size of the catalysts. The results show that diatomite is the promising candidate for catalytic support due to its high surface area, high porosity, low thermal conductivity, very low cost and good sorption ability of its porous media. The catalyst with 4wt % CuO content, in 0.5 l/min and at 400 ºC exhibited the highest catalytic activity. Diatomite, which is a type of widespread natural porous material, provides a suitable support. Chemical and physical characteristics of this support are similar to cordierite. Due to the numerous fine microscopic pores, cavities and channels good sorption ability, chemical inertness, low density, high surface area, unique combination of physical and chemical properties, high permeability and excellent thermal resistance of diatomite, there is a possibility to use it as a support in automotive catalytic converters and as a cost-effective substitute of noble metals for carbon monoxide oxidation. In addition, these unique properties of diatomite can prevent sintering and agglomeration of atoms.

Casting workers are facing with ergonomics hazards such as overload in Manual Material Handling (MMH) tasks which expose them to risk of work-related musculoskeletal disorders (WMSDs). There are several methods to determine acceptable weight among which, Snook table is one of the oldest one. The aim of the study was to assess prevalence of WMSDs and to investigate MMH tasks by Snook tables among casting workers. This cross-sectional study was conducted among 50 casting workers occupying in all of the five MMH tasks including lifting, lowering, carrying, pushing and pulling. Nordic Musculoskeletal Questionnaire (NMQ) and concise Snook tables were used to gathering required data. Statistical analyses were done using SPSS 16.0. The most common musculoskeletal disorders in one year prior to the study were hand wrist disorders (84%), low back pain (74%) and neck disorders (72%), respectively. The Snook tables results indicated that significant differences were found between acceptable weights and workers exerted load in lifting and lowering tasks (p<0.05) and also between acceptable forces and workers exerted force in pushing/pulling tasks (p<0.05). Overall, in most of cases exerted loads exceeded suggested weights. Regarding to results of the study, ergonomics interventions should focus on redesign of MMH tasks, improvement of workplace physical conditions and providing ergonomics instruments

life on Earth protected by ozone layer against harmful ultraviolet sun rays. Due to the destructive effects of chlorofluorocarbons (CFCs) on the ozone layer, other refrigerants were suggested such as HFC134a which is as an appropriate replacement for CFCs particularly CFC12. The aim of this study was determining the beliefs of refrigerator craftsmen to prevent health and environmental hazards of chlorofluorocarbons using of health belief model. This research was a descriptive- analytical and cross-sectional study. A number of 48 Refrigerator craftsmen from the cities of Tabas, Rafsanjan and Noorabad were studied by census method. The data collection tools in this study was a valid and reliable researcher made questionnaires consisting two parts: A- five demographic questions, B- questions and items about HBM: eight items Perceived susceptibility, five items Perceived severity, six items Perceived benefits, five items Perceived barriers, four questions Cues to action and Performance with four questions. The mean score of knowledge 10.77 ± 2.85 (score range 0-18), susceptibility 28.32 ± 3.95 (score range 8-40), severity 17.12 ± 2.38 (score range 5-25), benefits 20.49 ± 2.79 (score range 6-30), barriers 12.41 ± 1.26 (score range 5-25), Cues to action 0.61 ± 1.19 (score range 0-8) Performance 0.76 ± 1.08 (score range 0-8) were determined. Between the average score of knowledge and susceptibility (p<0.001, r=0.67), benefits (p<0.001, r=0.61) and severity (p=0.001, r =0.5) also between susceptibility and severity (p<0.001, r=0.66), susceptibility and benefits (p<0.001, r=0.84), susceptibility and performance (p=0.018, r=0.36), severity and benefits (p<0.001, r=0.58), and the benefits and performance (p=0.033, r=0.32), direct correlation and between the average score of work experience and knowledge (p=0.005, r= -0.419) an inverse correlation were obtained. The overal knowledge was not in acceptable level, and seeing that by increasing the knowledge of participants, the level of susceptibility, severity and benefits were also increased, the importance of education of Craftsmen need to be considered in order to improve preventive behaviors.