Journal of Health and Safety at Work

Introduction: Noise is one of hazardous agents of workplaces in industries. Electric industries and power plants are among industries in which noise pollution should be taken into account. This study aimed to develop and verify a statistical model for acoustic wave propagation in an indoor environment for noise related risk reduction management.

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Material and Method: This theoretical-experimental study was performed in a gas power plant with nominal capacity of 648 MW including four gas turbine with nominal capacity of 162 MW. The relations between sound power level and sound pressure level in indoor environments were used for developing the statistical model. Moreover, verification of the obtained data was done by a field inside a turbine hall study using ISO9612 standard method.

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Result: Comparison of results from the field and the theoretical study showed no significant differences. The differences between predicted value and field measurements was, in average, less than 0.5 db. This shows the acceptable accuracy of the presented model in estimating the workplace noise level, according to the real functional conditions of the noise sources.

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Conclusion: The presented model is easy and practical and allows managers to model scenarios of noise pollution reduction in indoor environments, before huge expenses of actual control measures. This method is faster comparing to numerical modeling methods. Furthermore, its accuracy is also acceptable.

Introduction: Investigation of accidents have shown that more than 90% of industrial accidents are related to human aspects. What is more, safe behaviors can not be institutionalized in industries by only using technical-engineering measures and enacting safety rules. Building a positive and effective safety culture can make individuals aware of hazards and consequently reduce accidents in the workplace.

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Material and Method: In this analytical-descriptive study, a standardized safety culture questionnaire was used. The questionnaire comprised of 40 question including five dimensions of: training, work environment, safety priority, information exchanges and management commitment. In this regard, the questionnaire was distributed among personnel of three laboratories in a petrochemical company. Five point Likert scale was for recording the responses.

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Result: The mean score for safety culture was 136.7 for laboratory personnel which was considered positive according to the presented definition. In this sense, safety priority and management commitment with score of 31.9 and 25.2 obtained respectively the dimensions of safety culture.

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Conclusion: Strong and positive safety culture among laboratory personnel would prevent incidence of many occupational accidents. In another word, it would help organizations to facilitate access to higher standards.

Introduction: Nowadays, using multi attribute decision making (MADM) techniques in HSE hazard rating have been widely increased. On the other hand, Analytical Network process (ANP) methods has a high flexibility and accuracy in decision ranking. Therefore, the combination of the two mentioned approaches can provide a more precise prioritization for HSE hazards. Using ANP techniques, in this research a method for accurate rating of HSE hazards in the construction procedure of combined cycle power plant was presented.

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Material and Method: In this study, first, the overall structure and components of ANP method were identified and the connections between its components were determined. Then, the determined structure and components were modeled, using super decision software. In the next stage, pair companions were performed between an criteria and sub-criteria with respect to HSE experts opinions, Finally, selected HSE hazards were prioritized and compared according to the presented ANP method and the common available method.

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Result: According to the results, common risk assessment method is not able to prioritized risk accurately. While the current method classified the ten main identified hazards in 4 general categories, the presented method in this study could prioritized then in 7 categories.

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Conclusion: The suggested ANP model could provide a more accurate prioritization for hazards in comparison with current methods because of considering five qualitative indices. This allows an optimal allocation of organizational resources for controlling hazards.

Introduction: Nowadays, computers are integral component of all workplaces. Moreover, employees healthstatus is directly associated with their occupational stress level. The aim of the present study was to investigative the effect of ergonomic training and intervention on reduction of occupational stress among computer users in welfare organization in Rasht city.

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Material and Method: In this semi experimental study, 283 female computer users, who were 30-40 years old with work experience of 5-15 years, were chosen as sample. The participants had at least one year experience of using computer and they had worked 3-4 hours with computer daily. The Osipow occupational stress questionnaire (1987) with Cronbach alpha 87% was applied for estimation of occupational stress. Then, 46 participants with moderate to high level of stress were selected and randomly divided into case ad control groups. Participants in a case group received practical and theoretical ergonomic training and also interventions (including armrest, foot rest, cushion, posture correction, reduction o work time duration, adjustment of the seat height according to individuals height, adjustment of eye-monitor distance). Finally, the obtained data were compared to those of control group, using covariance.

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Result: According to covariance analysis, ergonomic training and interventions lead to reduction of occupational stress of computer users.

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Conclusion: Training computer users and informing them of the ergonomic principals and also providing interventions such as correction of posture, reducing duration of work time, using armrest and footrest would have significant implication in reducing occupational stress among computer users.

Introduction: In the most industrial environment, workers are exposed to noise everyday. Exposure to this physical hazardous agent can cause immediate as well as delayed adverse effects. Cognitive performance decrement is one of the adverse effects of noise exposure which its main consequences is occupational accidents. This study attempted examine the effect of exposure to different levels of noise with harmonic indices of neutral, treble and bass on the cognitive performance.

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Material and Method: In this analytical-descriptive study, the cognitive tests were performed by 33 students, aged 23-35 years. During the tests, participants were exposed to three type of noise including neutral, treble and bass at 4 different levels of 45, 75, 85 and 95 decibels. In order to assess students cognitive performance, continuous performance test (CTP) software was employed, which investigated attrition and reaction time.

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Result: The results of this study revealed that exposure to neutral noises with Noise Harmonic Index (NHI) of +3dB at the frequency of 1000 Hz, the maximum percentage of attention (99.88 %) was belonged to Sound Pressure Level (SPL) of 95 decibels. Maximum percentage of attention due to exposure to the treble noise with NIH -105 dB at the noise frequency of 8000 Hz (100%) and bass noise with NIH of 407 dB at the frequency of 500 Hz (99.92%) were belonged to the SPL of 95 and 85 dBA, respectively. Moreover, the result showed that the effect of bass noise with NIH of 4.5 dB and frequency of 500 Hz on reduction of attention were more than treble noise with NIH of -105 dB and frequency of 8000 Hz. Under exposure to neutral noise with NIH of 3 dB and frequency of 1000 Hz, the longest reaction time (2.594 Second) was observed at the SPL of 85 dBA. The longest reaction time for treble noise with NIH of -105 dB and frequency of 8000 Hz (2.786 Second) and for the bass noises with NIH of 4.5 dB and frequency of 500 Hz (2.594 Second) were also belonged to the SPL of 85 and 75 dBA, respectively.

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Conclusion: The results showed that bass noises (frequency of 500 Hz) increased reaction time, in comparison with treble noises (frequency of 8000 Hz).

Introduction: Mercury is one of the toxic metals that damages the nervous system and kidneys. Therefore, monitoring of mercury vapors in the environments is essential.

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Material and Method: A new adsorbent was made from silver nanoparticles on a bed of quartz. The nano-adsorbent was capable for sampling of the trace amounts of mercury vapor from air. In this study, the required mercury vapor was generate by hydride generation atomic absorption spectrometry and the necessary analysis was performed by cold vapor atomic absorption spectrometry.

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Results: Mercury vapors in the Stationary phase, were concentrated as much as 2300 times (Atomic absorption detection limit was 1.15 microgram per liter of air). Thus by this stationary phase, the trace amounts of mercury vapors can be detected up to 0.5 nano gram per liter of air. The detected value of the presented method is 200 times lower than the occupational safety and health administration (OSHA) standards for mercury vapors. Heater accessory at the temperature of 245 °C was used for thermal desorption of mercury from nano silver adsorbent. Optimal time of desorption was obtained 150 seconds and the Repeatability of the method was 58 times. The mercury vapors absorbed on nano silver adsorbent could be maintained at 80 days at the room temperature (25 °C).

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Conclusion: The presented adsorbent is very useful for sampling of the trace amounts of mercury vapors from air. Moreover, it can be regenerated easily is suitable or sampling at 25 to 70 °C. Due to oxidation of silver and reduction in uptake of nanoparticles, oven temperature of 245 °C is used for the recovery of metallic silver. Low amount of adsorbent, high absorbency, high repeatability for sampling, low cost and high accuracy are of the advantages of the presented method.

Introduction: Electromagnetic field emitted by laptops are known as extremely low frequency (ELF) Waves. The aim of this study was to investigate the intensity of electric and magnetic field with extremely low frequency emitted by common laptops.

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Material and Method: Intensity of electric and magnetic field were measured on four sides of 40 common by used laptop at the distance of 30, 60 and 90 cm. Measurements ere done according to standard in four functional model including: non-performing turned on, sleep mode, performing office program and performing audio visual files.

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Result: Magnetic field values for all laptops were almost constant and about 28-32 mA/m. The results of measurements related to the electric field showed different values at distances of 30, 60 and 90 cm around the laptops on four sides. Moreover, mean electric field on the keyboard at the four operating modes were statistically different for DELL and hp laptops (P< 0/05).

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Conclusion: The results of this study showed that laptops produce extremely low frequency (ELF) electric and magnetic fields which their intensity depends on laptop type, laptop operation mode and the location of the measurement.

Introduction: The previous studies have used fibrous absorbents usually in the form of cone-shaped wedges for making anechoic and semi-anechoic chambers which their design and construction have been costly and difficult. The present study aimed to design a semi-anechoic chamber, using rectangular fibrous absorbents and also perform acoustic analysis for it.

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Material and Method: In the present study, which was done at semi-anechoic chamber of the laboratory in Tehran University of Medical Sciences. The reverberation time, the total surface and the absorption surface of the chamber were determined, before and after the design and also they were compared with the target values. Intersection layout of the rectangular fibrous absorbents were design using graphic design software (AutoCAD and 3Ds Max). before design, the reverberation time were measured according to ISO 3382:2000. The reverberation time in redesigned chamber was also calculated through retention time equation (Sabine). Moreover, Sabin’s formula was applied for determining the absorption surface and the total surface of the chamber, before and after the design.

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Result: Before design, the reverberation time in the cut-off frequency of 250 Hz according to ISO 3382:2000 was determined 0.3 second. Moreover, the total chamber surface was 47.97 m2. CAD software estimated at least 253 rectangular absorbents with dimensions of 50×18 cm. After design, the absorption surface and the total chamber surface were obtained 46.32 m2 and92.64 m2, respectively and the reverberation time in the mentioned frequency was 0.07 (s).

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Conclusion: According to the results, it can be concluded that the suggested intersection layout of rectangular fibrous absorbents can be used as a reliable method in order to reduce the reverberation time and to gain lower cut-off frequency for construct a semi anechoic chamber with the high efficiency.

Introduction: Individuals’ jobs performance is one the most important factors in industries and organizations. The aim of the present study was to investigate the simultaneous effect of exposure to noise, lighting and heat stress on the workers’ job performance.
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Material and Method: In this analytical-descriptive study, 30 employees of the auto parts manufacturer, in Tehran city, were chosen by simple random sampling. By controlling and limiting confounding factors, the simultaneous effect of noise, lighting and heat stress on the participants’ job performance was investigated, using tow series of mental and manual testes. Data were analyzed by SPSS software version 18, using descriptive statistic, ANOVA and Tukey testes and also person correlation coefficient.
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Result: The results showed that by increasing the noise and heat stress (P = 0.046, r=0.344) and decreasing of lighting (P =0.008, r = -0.472), the required time for performing the Minnesota placement test has been gone up. Moreover, the result revealed that by increase in noise and heat stress (P = 0.007, r = 0.478) and decrease in lighting (P=0.003, r = 0.523) the required time for competing hand tool dexterity test has been also increased at surface and mid level.
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Conclusion: Finding of the present research manifested that increase in noise and heat stress and also reduction in lighting lessen the speed of manual tests and time and accuracy of mathematical calculations. Therefore this result confirm the effects of various environmental factors on individuals’ job performance, in a way that by variation of different environmental factors, time of manual test and time and accuracy of mental tests would be changed.

Introduction: IBioaerosols are usually defined as aerosols or particles with microbial, plant or animal origin. Textile industries are of the working environments in witch workers are exposed to bioaerosols. In textile industry, the highest contamination concentration is the belonged to carding step. Since, textile industry in iran is native and a large number of employers are working in this industry, this study was undertaken to assess bacterial bioaerosols concentration in a textile in industry in iran.
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Material and Method: In cross-sectional study was done in different units and also outdoor environment of a cotton textile plant. The concentration of bioaerosols were sampled and measured according 0800 method presented by NIOSH, during summer. Diagnosis of type of colonies and bactories, grown on blood agar, was done using gram staining.
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Result: The mean bioaerosols concentration obtained the highest and lowest values in outdoor environment (94±9.5 CFU/m3) and unit 2 (Ring site) (64±18.0 CFU/m3), respectively. The mean difference of bioaerosols concentration in unit 1 (Carding sites) and unit 2 (Ring site), was statistically significant in this study. The highest number of bioaerosols colony was for staphylococcus Epiderms (N=1743) and the lowest number was for streptococcus pneumonia (N=64) in the whole plant.
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Conclusion: Although the bioaerosols concentration obtained in the present study is lower than those reported in other studies, these values are above the threshold recommended.

Introduction: Heat stress is considered as one of the hazardous occupational agents in hot environments. Working under heat stress condition may lead to individuals’ health problems. Several studies have been shown that stress in the working environments can elevate stress hormones such as cortisol. Since heat stress is one of the serious stresses in hot industries including melting, this study was done to investigate the effect of heat stress on the cortisol concentration of workers in one of the melting industries.
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Material and Method: In this cross-sectional study, 70 workers in two groups of case and control (35 people in case group from foundry unit and 35 people in control group from casting unit without heat stress) were investigated. First, a demographic questionnaire was complete for each subject. Then in order to evaluate the changes in cortisol level, blood samples were taken from the participants during their working hours (9:30 to 10 AM) and the obtained levels were compared with the normal level of cortisol, provided at 7 to 10 AM. In order to assess environmental condition, WBGT (Wet Bulb Globe Temperature) index was measured at three highest including feet, waist and head. Moreover, noise and lighting were measured at the workers work station. Data were analyzed using SPSS software version 16.
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Result: Regarding WBGT, it was shown that mean WBGT index were 33 C and 16.7 C in case and control groups, respectively. Additionally, cortisol concentration in case group was significantly higher than control group (P<0.001).
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Conclusion: Results of the present study indicate that physical stresses of working environment can lead to changes in physiology of human body. Thus, variations in hormone level in its consequences in hot environment should be considered in occupational hygine.

Introduction: Biorhythm is one of the newest subject in the field of cognition of mental ergonomics which can be very effective in reduction of work-related accidents or mistakes with no apparent reason.
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Material and Method: This research is a cross-sectional, retrospective, practical and analytical-descriptive study. Delijan cement production company during 2010-2011. Census method was applied and totally 79 accidents (total of the accidents) were investigated. The required information was collected from available documents in HSE unit of the company biorhythm charts were drawn based on a dates of accidents and participants birthdays, using Natural Biorhythm Software V3.02. Human errors were classified according to reason model and were analyzed by SPSS-W software.
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Result: The results of analysis showed that 40% of accidents have been accrued in usual days and the other 60% in critical days of biorhythm cycle. Regarding errors leading to accidents, it was observed that 95% of accidents were related to human error and 5% related to equipment errors. Moreover, 65.8% of the human errors were associated with the slipping which happens during performing a task, according to reason model.
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Conclusion: Findings of this research showed that bad and critical days of individuals’ biorhythms cycle influence the occurrence of accidents. Therefore, by training and increasing the knowledge of workers regarding biological cycle and its effects on mental, emotional and physical status, each person effects can make some changes to theire work plans during days that they do not feel well, physically or mentally, in order to prevent the likely accidents.

Introduction: Air health is an important environmental issue which has been endangered in recent years due to application of advanced technologies used for improving the financial welfare and relative prosperity of humans. Making use of pollution control systems and refinement methods are some general ways to control environmental pollution. Since several different techniques of control, each with its advantages and disadvantages are employed in order to mitigate the spread of air pollution, the aim of current study was to design a fuzzy multi-attribute decision making model to select the most appropriate air pollution control equipment in Mashhad Shargh Cement Company.
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Material and Method: After identifying the desired industry and also the production process, all factors affecting decision-making process including environmental factors, technical factors and economic factors were considered by utilizing Fuzzy Analytic Hierarchy Process method. Importance weight of these criteria was calculated and subsequently the priority of model choices were also determined using this approach.
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Result: Among main criteria of the model, economic criteria was identified as the most important factor influencing the selection of the type of air pollution control equipment, with the wight of 0.555. Environmental and technical factors with weighting of 0,286 and 0,159 also gained the next priorities, respectively. Final weights of Electro filter, Baghouse and Hybrid filter technologies were calculated 0.256, 0.415 and 0.329 in cement mill unit and 0.291, 0.374 and 0.334 in material grinding and furnace unit, respectively.
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Conclusion: Finally, the proposed model that is based on the Fuzzy Analytic Hierarchy Process indicates that the Baghouse Technique is the most appropriate technique for the purpose of dust filtration in major sources of air pollution spread in Shargh Cement Company.

Introduction: The present study was carried out to compare contrast sensitivity among three groups of professional welders including (1) those who use gas metal Arc welding (GMAW) (2) those who use shield metal Arc welding (SMAW) and the group that uses resistance welding.
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Material and Method: In this research, all the welders who use GMAW, SMAW and resistance welding working in an industry who were all male, performed contrast sensitivity test, using Freiburg. The contrast sensitivity test was done at three spatial frequency of 1cpd, 5cpd and 15 cpd under a constant condition. The three selected groups were similar regarding age and work experience. The result of the three groups at each spatial frequency were recorded and compared with other groups.
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Results: ANOVA test showed that decrease contrast sensitivity in spatial frequency of GMAW group at the spatial frequency 15cpd, significantly decrease comparing to SMAW group (p=0.028) and resistance welding group (p=0.041). The mean (SD) of contrast sensitivity at frequency of 1cpd, 5cpd and 15cpd was respectively 140.69±51.8, 172.7±43.75 and 39.8±25.92 for the GMAW group and 157.8±42.2, 183.21±32.01 and 60.57±54.30 for the SMAW group and 149.10±50.68, 180.60±35.42 and 57.38±39.22 for resistance welding.
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Conclusion: Although all welders use goggle or other personal protective equipment, loss of contrast sensitivity of GMAW workers can be attributed to the cumulative effects of the radiation.

Introduction: Whole body vibration occurs when human is on a vibrating surface and the vibration influences parts of the body which are far from the contacted part. Up to now, various health-related problems due to whole body vibration have been reported, including back pain, sciatica, gastrointestinal problems, genital problems and hearing impairment. In the present research, vibration was measured about 2000 minutes in 23 train of 4 active lines of Tehran metro in order to determine the rate of subway drivers’ exposed to whole body vibration.
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Material and Method: Vibration meter and SVAN 958 analyzer, made by Svantek company, were utilized for measuring the whole body vibration. The level of weighted r.m.s acceleration for each axis, the combination of axes, peak factor, VDV and other common exiting ratios in the standard were measured and calculated according to ISO 2631-1.
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Result: Findings showed that according to Basic method drivers exposure to vibration is less than the lowest value of health guide critical region (<0.45m/s2). However, based on Vibration Dose Valuation (VDV), the exposure of 12 cases were higher than the lowest value (<8.5 m/s1.75) and only 11 cases were lower than the mentioned amount.
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Conclusion: Investigation of the result obtained from Basic method and VDV method manifested different amounts of vibration exposure in a way that VDV predicts higher level of risk, compared to basic method. The results shows that some presented indicators can not presented the safe zone in human vibration evaluations.

Introduction: Chromium (VI) is a known human carcinogenic agent which is used in numerous industrial processes such as electroplating, welding, textile, cement and steel fabrication. The aim of this study was to determine the effectiveness of natural zeolite on the fixed bed adsorption of Cr (VI) from air stream.
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Material and Method: In this experimental study, chromium mists were generated by a nebulizer (3A model, Italy). Performance of natural zeolite in the Cr (VI) adsorption and its influencing factors such as air flow rate (1 and 3 L/min), the initial Cr concentration (0.05, 0.15, 1 and 10 mg/m³) and the bed depth (2.5, 5 and 10 cm) were investigated.
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Result: Zeolite adsorption capacity elevated by the increasing of bed depth but decreased with increasing of flow rate and inlet concentration. In order to facilitate the prediction of natural zeolite column performance Yoon-Nelson and Thomas models were used. The results showed that these models have a good agreement with our experimental data.
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Conclusion: Due to the extensive use of chromium in various industries and regulatory requirements related to workplace health and safety, Cr emission control in the occupational environment is essential. The adsorption process is one of the controlling measures of chromium emissions. The results indicated that natural zeolite has a high efficiency in Cr (VI) adsorption.

Introduction: Job design approach is one of the significant concepts in ergonomics Experts believe that integration of macro ergonomics and job design can lead to improved productivity in the organizations. Therefore, this study examined the relationships between job design, performance and job satisfaction.

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Methods and Materials: This cross - sectional study was done in 11 branches of one of the bank in Hamadan. Job Design Questionnaire, Job Satisfaction Questionnaires and Bank Performance Indicator were used in order to collect data. spearman correlation coefficient was used for determining the correlation between each two variables.

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Results: This study showed that the motivational approach was the minimum approach (3.8%), and the mechanical approach, was the dominant approach (74.7%) in the study branches and the majority of branches had an average level of job satisfaction. Moreover, there was a significant positive correlation between job design (motivational and cognitive approaches) and job satisfaction. In addition, the results showed that between job design (Motivational approach) and satisfaction were significantly correlated with performance, (p = 0.05).

Conclusion: Regarding the role of job design in job satisfaction and employees, performance, it can be stated that job redesign towards a motivational approach and considering the principles of ergonomics in the workplace, can play an important role in efficiency and productivity of an organization.

Introduction: Statistical Report of the Social Security Organization indicate that among the various industries, the construction industry has the highest number of work-related accidents so that in addition to frequency, it has high intensity, as well. On the other hand, a large number of human resources are working in this whish shows they necessity for paying special attention to these workers. Therefore, risk assessment of the safety in the construction industry is an effective step in this regard. In this study, a method for ranking safety risks in conditions of low number of samples and uncertainty is presented, using gray multi-criterion decision-making.

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Material and Method: In this study, we first identified the factors affecting the occurrence of hazards in the construction industry. Then, appropriate for ranking the risks were determined and the problem was defined as a multi-criterion decision-making. In order to weight the criteria and to evaluate alternatives based on each criterion, gray numbers were used. In the last stage, the problem was solved using the gray possibility degree.

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Results: The results show that the method of gray multi-criterion decision-making is an effective method for ranking risks in situations of low samples compared with other methods of MCDM.

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Conclusion: The proposed method is preferred to fuzzy methods and statistics in uncertain and low sample size, due to simple calculations and no need to define the membership function.

Introduction: One of the factors influencing on indoor air quality of the buildings is performance of HVAC (heating, ventilation, and air conditioning) systems. These systems supply clean and odorless air, with temperature, humidity, and air velocity within comfort ranges for the residents. The aim of this study was to evaluate performance HVAC system in an administrative building in Tehran.

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Material and Method: A questionnaire, developed in their research was used to assess the building occupants’ perception about the performance of HVAC system. To evaluate the performance of HVAC systems, air velocities were measured in the diffusers using a thermal anemometer. Moreover, CO2 concentration, air temperature and relative humidity were measured in the whole floors of the building. Air distribution inside the building was evaluated using smoke test.

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Results: Most of the studied people complained about the direction of airflow, thermal conditions and cigarette odor. The highest level of carbon dioxide was measured at 930 ppm inside the restaurant. The maximum and minimum air temperatures and relative humidity were measured 28.3-13.8° C and 28.4-23% respectively. Smoke test showed that the air distribution/direction wasn’t suitable in one third of air diffusers.

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Conclusion: Improper air distribution / direction was the main problem with the studied HVAC system which could be corrected by adjusting and balancing of the system.

Introduction: Heat-related illnesses are major causes of morbidity in the world. Workers who are exposed to extreme heat are not be able to activate their compensatory mechanisms and their health will consequently be at risk. Heat stress due to its impact on work performance increases the likelihood of worker disease and injuries and it also affect productivity. During sugar beet harvest, farmers from about 8 am to 4 pm, are exposed to sunlight and excessive heat. Therefore, preventive measures are essential in order to protect the health of farmers and improve productivity. The aim of this project as to study the effectiveness of the rehydration to reduce heat stress and increasing productivity during sugar beet harvest, conducted in 2012.

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Material and Method: in this project, 20 farmers from sugar beet farmers were studied during summer season, from 8 am to 4 pm in West Azarbaijan- Boukan city where the average temperature and relative humidity were 29.85 0C and 41%, respectively during sugar beet harvest. Selection criteria were defined as working more than 50% of the day’s working schedule and to have worked for at least 10 days of the follow-up period. Individual characteristics and water consumption rate during the work shift and also Production output data by farmers were recorded at the end of the working day. Environmental parameters using a portable monitoring device was measured and recorded and finally, the collected data was used for analysis using spss software version 20.

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Results: WBGT-TWA index for four the period of the time from morning to afternoon obtained 27.39 0C, as it was greater than the allowable thresholds. Ten workers receive 6-7 L of liquid and harvest production was significantly increased among those who are better hydrated (P=0.005), from 5 to 7 tons of harvest sugar beet per any worker per day, against lower 5 tons for farmers without drinking enough water.

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Conclusion: Farmers productivity can be increased by applying rehydration measures during work.