Field Study of Effects of Night Shifts on Cognitive Performance, Salivary Melatonin, and Sleep

BACKGROUND: Night shift work is associated with many problems such as sleep deprivation, sleepiness, decreased cognitive performance, increased human errors, and fatigue. This study set out to measure cognitive performance, melatonin rhythms, and sleep after different consecutive night shifts (7 vs. 4) among control room operators (CORs). METHODS: The participants included 60 CORs with a mean age of 30.2 years (standard deviation, 2.0) from a petrochemical complex located in Southern Iran. Cognitive performance was assessed using the n-back task and continuous performance test. To evaluate melatonin, saliva was collected and tested by enzyme-linked immunosorbent assay. To assess sleep and sleepiness, the Pittsburgh Sleep Quality Index and Karolinska Sleepiness Scale were used, respectively. RESULTS: Individuals who worked 7 consecutive night shifts had a significantly better cognitive performance and sleep quality than those who worked 4 consecutive night shifts. However, salivary melatonin profile and sleepiness trend were not affected by shift type. CONCLUSION: The main duty of CORs working night shifts at the studied industry included managing safety-critical processes through complex displays; a responsibility that demands good cognitive performance and alertness. It is suggested that an appropriate number of consecutive night shifts in a rotating shift system should be planned with the ultimate aim of improving CROs performance/alertness and enhancing safety.

Evaluation of the Quality of Occupational Health and Safety Management Systems Based on Key Performance Indicators in Certified Organizations

BACKGROUND: Occupational Health and Safety Management Systems are becoming more widespread in organizations. Consequently, their effectiveness has become a core topic for researchers. This paper evaluates the performance of the Occupational Health and Safety Assessment Series 18001 specification in certified companies in Iran. METHODS: The evaluation is based on a comparison of specific criteria and indictors related to occupational health and safety management practices in three certified and three noncertified companies. RESULTS: Findings indicate that the performance of certified companies with respect to occupational health and safety management practices is significantly better than that of noncertified companies. CONCLUSION: Occupational Health and Safety Assessment Series 18001-certified companies have a better level of occupational health and safety; this supports the argument that Occupational Health and Safety Management Systems play an important strategic role in health and safety in the workplace.

Individual Fit Testing of Hearing Protection Devices Based on Microphone in Real Ear

BACKGROUND: Labeled noise reduction (NR) data presented by manufacturers are considered one of the main challenging issues for occupational experts in employing hearing protection devices (HPDs). This study aimed to determine the actual NR data of typical HPDs using the objective fit testing method with a microphone in real ear (MIRE) method. METHODS: Five available commercially earmuff protectors were investigated in 30 workers exposed to reference noise source according to the standard method, ISO 11904-1. Personal attenuation rating (PAR) of the earmuffs was measured based on the MIRE method using a noise dosimeter (SVANTEK, model SV 102). RESULTS: The results showed that means of PAR of the earmuffs are from 49% to 86% of the nominal NR rating. The PAR values of earmuffs when a typical eyewear was worn differed statistically (p 0.05). CONCLUSION: This study could provide local individual fit data. Ergonomic aspects of the earmuffs and different levels of users experience and awareness can be considered the main factors affecting individual fitting compared with the laboratory condition for acquiring the labeled NR data. Based on the obtained fit testing results, the field application of MIRE can be employed for complementary studies in real workstations while workers perform their regular work duties.

Comparative analysis of lighting characteristics and ultraviolet emissions from commercial compact fluorescent and incandescent lamps

Background: Some characteristics of lighting sources such as color properties and ultraviolet emissions have important roles on visual and non-visual health effects of lighting

This study aimed to investigate the light emissions of some compact fluorescent lamps [CFLs] and incandescent lamps commercially available to the Iranian consumers

Methods: Sixty lamps included 48 single envelope CFLs, and 12 incandescent lamps available in the electrical devices markets [in the west of Iran] were randomly selected from famous manufacturers between 2014 and 2015. Lighting characteristics and ultraviolet [UV] emissions were measured using spectroradiometer and calibrated radiometer, respectively. Data analysis was performed using SPSS 16 software

Results: Color-rendering indexes of the studied lamps were above 80, which showed good color properties

The daylight CFLs had more desirable and natural color temperature [near to 5000 °k] compared with the other types of the studied lamps. Occupational exposures for periods up 8 h to UVB from the studied lamps at distances up to 0.25 m were more than the recommended limits. Moreover, public exposures for periods up 16 h to UVB from the studied lamps at any distances up to 2 m were more than the recommended limits

Conclusions: Warm white lamps are suitable for homes usage, while daylight lamps can be used for offices rooms. Occupational exposure to single envelope CFLs near the body at distances of less than 25 cm can result in overexposure to actinic UV. Moreover, CFLs must be used at distances greater than 200 cm for public exposure

passive noise control approach utilizing air gaps with fibrous materials in the textile industry

Noise pollution is currently a major risk factor in industries in both developed and developing countries.The present study assessed noise pollution in the knitting industry in Iran in 2009 and presented a control method to reduce the rate of noise generation. The overall noise level was estimated using the network environmental noise as-sessment method in Sina Poud textile mill in Hamadan. Then, frequency analysis was per-formed at indicator target stations in the linear network. Finally, a suitable absorbent was rec-ommended for the ceilings, walls, and aerial panels at three phases according to the results found for the sound source and destination environment. The results showed that the highest sound pressure level was 98.5 dB and the lowest was 95.1 dB. The dominant frequency for the industry was 500 Hz. The highest and lowest sound suppression was achieved by intervention at 4000 Hz equivalent to 14.6 dB and 250 Hz in the textile industry. When noise control at the source is not available or insufficient because of the wide distribution of the acoustic field in the workplace, the best option is to increase the absorp-tive surface of the workplace using adsorbents such as polystyrene.

Development of a noise prediction model based on advanced fuzzy approaches in typical industrial workrooms

Noise prediction is considered to be the best method for evaluating cost-preventative noise controls in industrial workrooms. One of the most important issues is the development of accurate models for analysis of the complex relationships among acoustic features affecting noise level in workrooms. In this study, advanced fuzzy approaches were employed to develop relatively accurate models for predicting noise in noisy industrial workrooms. The data were collected from 60 industrial embroidery workrooms in the Khorasan Province, East of Iran. The main acoustic and embroidery process features that influence the noise were used to develop prediction models using MATLAB software. Multiple regression technique was also employed and its results were compared with those of fuzzy approaches. Prediction errors of all prediction models based on fuzzy approaches were within the acceptable level [lower than one dB]. However, Neuro-fuzzy model [RMSE=0.53dB and R[2]=0.88] could slightly improve the accuracy of noise prediction compared with generate fuzzy model. Moreover, fuzzy approaches provided more accurate predictions than did regression technique. The developed models based on fuzzy approaches as useful prediction tools give professionals the opportunity to have an optimum decision about the effectiveness of acoustic treatment scenarios in embroidery workrooms

intervention for noise control of blast furnace in steel industry

Noise pollution is currently a major health risk factor for workers in industries. The aim of this study was to investigate noise pollution and implement a control intervention plan for blast furnace in a steel industry. The measurement of sound pressure level [SPL] along with frequency analysis was done with the sound-level-meter Cell-450. Personal noise exposure was performed using dosimeter TES-1345 calibrated with CEL-282. Before planning noise controls, acoustic insulation properties of the furnace control unit and workers' rest room were assessed. Control room and workers' rest room were redesigned in order to improve acoustical condition. The SPL before intervention around the Blast Furnace was 90.3 dB [L] and its dominant frequency was 4000 Hz. Besides, noise transmission loss of the control and rest rooms were 10.3 dB and 4.2 dB, respectively. After intervention, noise reduction rates in the control and rest rooms were 27.4 dB and 27.7 dB, respectively. The workers' noise dose before and after the intervention was 240% and less than 100%, respectively. Improvement the workroom acoustic conditions through noise insulation can be considered effective method for preventing workers exposure to harmful noise

Noise annoyance due to construction worksites

Noise pollution can contribute to adverse health effects in humans. Noise annoyance and related problems, caused by noise emission during the progress of building construction, have become increasingly important. These problems can influence the exposed workers, as well as vicinity residents. The goal of the present study was to assess the noise annoyance due to noise from construction worksites among residents of Hamadan City [west of Iran]. In this cross-sectional study, 20 construction worksites and 140 near vicinity residents were selected. The main sources of construction worksite noise were diesel power generators, cutting and welding processes, heavy machinery [such as trucks] and transport of materials. Ambient noise levels were measured using a calibrated sound level meter, at each home of the residents included in the study. A noise annoyance questionnaire was employed for annoyance assessment. The majority of subjects had very high annoyance [87.1%]. The mean and SD of ambient levels were 74.57 +/- 7.12 dB [A] which exceeded the acceptable recommended level for residential areas. The most common problems among the participants were disturbance in sleep, difficulty in reading and distraction. Results showed significant relationship between noise annoyance and some factors including residing which floors had highest annoyance [F=13.22, P<0.001] and ambient noise [F=11.313, P<0.001]. High levels of noise annoyance among near vicinity residents who are affected by construction activities. This means that construction activities and other noise related sources should be regarded as the major source of ambient noise leading to noise annoyance

Effect of noise exposure on occupational injuries: a cross-sectional study

Noise exposure is the most frequent occupational factor which may increase the risk of work-related injuries. The purpose of this study was to estimate the association between occupational injuries and noise exposure as well as hearing loss. This study was conducted from April 2008 to March 2009 on 1062 workers in the Tabriz Tractor Manufacturing Plant. Sound pressure level [SPL] >/= 85 dB in the workplace was considered as the independent variable [exposure] and physical occupational injuries as the dependent variable [outcome]. Data were extracted from the workers' medical records using a checklist. Of 1062 volunteers, 392 [36.9%] were exposed [with SPL >/= 85 dB] and 670 [63.1%] were unexposed [with SPL<85 dB]. One hundred and seventy-six injuries occurred during the study period. Frequency of injuries was about 16 per 200,000 hours, severity of injuries was about 75 per 200,000 hours and incidence rate of injuries was 16%. The exposed group had 1.52 fold increased risk of injury compared to unexposed group [P=0.012]. Compared to group with normal hearing status, the risk of occupational injuries increased 1.72 fold in group with partial hearing loss [P=0.062], 7.87 fold in group with mild hearing loss [P=0.003], and 4.58 in group with moderate hearing loss [P=0.049]. Occupational noise exposure and hearing impairment have adverse effect on work safety and can increase the probability of work-related injuries. This means reducing noise exposure can contribute to increase safety in workplaces where noise is a factor. Furthermore, using assistive listening devices may reduce risk of work injuries among hearing-impaired workers

Assessment and control design for steam vent noise in an oil refinery

Noise is one of the most important harmful agents in work environment. Noise pollution in oil refinery industries is related to workers' health. This study aimed to determine the overall noise pollution of an oil refinery operation and its frequency analysis to determine the control plan for a vent noise in these industries. This experimental study performed in control unit of Tehran Oil Refinery in 2008. To determine the noise distributions, environmental noise measurements were carried out by lattice method according to basic information and technical process. The sound pressure level and frequency distribution was measured for each study sources subject separately was performed individually. According to the vent's specification, the measured steam noise characteristics reviewed and compared to the theoretical results of steam noise estimation. Eventually, a double expansion muffler was designed. Data analysis and graphical design were carried out using Excel software. The results of environmental noise measurements indicated that the level of sound pressure was above the national permitted level [85 dB [A]]. The Mean level of sound pressure of the studied steam jet was 90.3 dB [L]. The results of noise frequency analysis for the steam vents showed that the dominant frequency was 4000 Hz. To obtain 17 dB noise reductions, a double chamber aluminum muffler with 500 mm length and 200 mm diameter consisting pipe drilled was designed. The characteristics of steam vent noise were separated from other sources, a double expansion muffler was designed using a new method based on the level of steam noise, and principle sound frequency, a double expansion muffler was designed

Comparison of ergonomic risk assessment outputs from rapid entire body assessment and quick exposure check in an engine oil company

During the last decades, to assess the risk factors of work-related musculoskeletal disorders [WMSDs], enormous observational methods have been developed. Rapid Entire Body Assessment [REBA] and Quick Exposure Check [QEC] are two general methods in this field. This study aimed to compare ergonomic risk assessment outputs from QEC and REBA in terms of agreement in distribution of postural loading scores based on analysis of working postures. This cross-sectional study was conducted in an engine oil company in which 40 jobs were studied. All jobs were observed by a trained occupational health practitioner. Job information was collected to ensure the completion of ergonomic risk assessment tools, including QEC, and REBA. The result revealed that there was a significant correlation between final scores [r=0.731] and the action levels [r =0.893] of two applied methods. Comparison between the action levels and final scores of two methods showed that there was no significant difference among working departments. Most of studied postures acquired low and moderate risk level in QEC assessment [low risk=20%, moderate risk=50% and High risk=30%] and in REBA assessment [low risk=15%, moderate risk=60% and high risk=25%]. There is a significant correlation between two methods. They have a strong correlation in identifying risky jobs, and determining the potential risk for incidence of WMSDs. Therefore, there is possibility for researchers to apply interchangeably both methods, for postural risk assessment in appropriate working environments

Evaluation of noise propagation characteristics of compressors in Tehran oil refinery center and presenting control methods

The adverse effects of noise are well known and noise problems due to industrialization of communities are increasing over the time. Oil industries due to the process and nature of production; contain many noise sources such as compressors, turbines, and pumps, which cause excessive noise exposure. The objective of this study was to evaluate the noise characteristics of compressors in Tehran Oil Refinery and study on visible control measures. To get to the appropriate control method, procedures such as basic theories, measuring sound parameters, frequency analysis, related diagrams and noise propagation schemes due to the measurement results, equivalent noise exposure level [L[eq[8h]]] and exposure noise dose and technical specification of compressors are considered in this paper. Considering field and analytical results, module enclosure with particular specifications [like absorbent layer, specific wall, window and door design etc.] is predicted to be the best control method. Calculation results of multiple layer density of the enclosure [W=16.5 kg/m[2]] and needed density for the dominant frequency of the source [W=12 kg/m[2]] demonstrated that the designed enclosure satisfies the goal. Results of designing sandwich layers' module demonstrated that installing the designed enclosure causes 20 dB[A] reduction in total sound pressure level of the source's dominant frequency

[ relationship between job stress and occupational accidents in an automobile manufacturing company]

Automobile manufacturing industries are consider among the main sites where accidents are likely to happen. From a cognitive point of view, stress can cause problems such as poor concentration, absent-mindedness, and hesitancy while making decision. This study examines the relationship between job stress and occupational accidents in an automobile manufacturing company. For this descriptive- analytic study, the psychological stress of the occupational groups was measured using standard job stress questionnaire. Safety Behavior Sampling [SBS] technique was used to collect samples of dangerous behaviors. Data were then analyzed using descriptive statistic, ANOVA, Pearson correlation coefficient and Logistic regression tests. Based on our results 88% of the sample suffered from a high level of occupational stress. There was also a statistically significant correlation between level of stress and number of accidents experienced by an individual. [P<0.05]. Having considered the relationship between occupational stress and work-related accidents, minimizing or eliminating risk factors need to be carried out through developing occupational stress management programs as well as following safety measures through reinforcing principles of safe behavior at all levels of organization