Iranian Journal of

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Backgrounds and Objectives: Noise in large cities is considered by the World Health Organization to be the third most hazardous type of pollution. Buses are an interesting object of study in the theme of noise pollution. They are at the same time a source of urban environmental (traffic) noise and occupational noise exposure source for drivers. The object of this study is Occupational noise exposure evaluation in drivers of bus transportation of Tehran city.
Materials and Methods: Noise levels in 90 buses were sampled in three separate sub-sample including (1)30 Ikaroos buses (2)30 Man buses (3)30 Shahab buses, which were selected by simple random sampling. Noise exposure level was normalized to a nominal 8-h working day (LEX, 8h). Simultaneous Octave Frequency Analysis were measured and sound intensity level (SIL) for bus drivers were calculated. Results, which are obtained from separate buses were compared together and too with standard levels.
Results: the normalized noise exposure levels (LEX, 8h) in Ikaroos bus drivers(82dB A) were higher than that of in in Man bus drivers (77/6dB A) and this Values were higher than that of in Shahab bus drivers(75dB A).SIL values for Ikaroos bus drivers were higher than other that of other bus drivers. Results obtained of Frequency Analysis showed that age of buses in mid frequencies ws a meaningful on noise increase.
Conclusion: Results showed that type and age of buses were effective factors in drivers. noise exposure levels (LEX, 8h), which was consistent with previous studies in this field.

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Background and Objectives: with the developments of technology, contact with various frequencies of electromagnetic fields ( EMF ) has significantly increased, while the abundant benefits of using microwaves in routine life cannot be neglected. During recent years there have been reports of adverse effects caused by contact with electric and magnetic fields of these waves that spread from BTS antennas. The purpose of this study is the measurement of microwaves spreading around BTS antennas in Tehran.
Materials and Methods:  according to the location of BTS antennas in Tehran , power density of electromagnetic waves around 63 antennas in near and distant fields in different distances was measured. The measurements were performed using the standard method of IEEE Std C95.1 by Hi-4333 device .in order to analysis  data we used spss 16 and descriptive and deductive statistical tests.
Results: results of this study show that in the near field, with increase of distance  from the foot of antenna , the  average power density of electromagnetic waves increase in a way that in the distance of 10 meters from the antenna foot , the increase of average power density is hardly conceivable and from 10 to 15 meters distance is perfectly noticeable. But in the distant field, with increase of distance from 20 meters, the average power density of the electromagnetic waves decreases and from 100 meter and further, the gradient of the diagram will get almost linear and the rate of power density reaches the base limit in a way that with the increase of distance there would be no significant decrease.
Conclusion: All the measures of power density of electromagnetic waves caused by BTSs are about 0.06% of recommended measures of environmental standards and 0.0000013% of occupational standards. The results of this study are close to the results of other studies.

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MicrosoftInternetExplorer4 Background and Objectives: Heat stress is considered as a serious threat to the health and safety of workers in many industries, including petrochemical and steel. Assessment of the heat stress is important from the disease prevention point of view and also for the safety and performance of workers at workplace. Although there are many indices to evaluate the heat stress, it is hard to select an applicable index for a wide range of weather conditions. The purpose of the study was to develop an optimal index based on physiological parameters in a petrochemical industry. 
Materials and Methods: The study was conducted in a petrochemical industry located in Assaluyeh (south of Iran). Twenty one healthy young men at different levels of fitness and heat acclimation volunteered to participate in the study. Physiological parameters including heart rate, systolic and diastolic blood pressure, skin temperature and oral temperature were measured during the working day over two consecutive weeks. Simultaneously, we measured the climatic parameters required to calculate the wet bulb globe temperature (WBGT), required sweat rate (SWreq), and the discomfort index (DI) indices.
Results: All the measurements took place on 2 sites: Kar (working place) and Paziresh (resting room). Our results showed  that the mean values of indices and physiological parameters   in Kar    for both acclimated and unacclimated groups were significantly higher than Paziresh (P<0.05). There was the strongest linear correlation between WBGT and heart rate (0.731), systolic blood pressure (0.695) and diastolic blood pressure (0.375) and skin temperature (0.451) respectively. The amounts of DI were 0.725, 0.446, 0.352, and 0.689 respectively. But the strongest linear relationship existed between SWreq and deep body temperature (0.766).
Conclusion:  There were significant differences in the present indices and physiological parameters of Kar and Paziresh, confirming the previous studies findings. Finally, WBGT was considered optimal index and the results revealed the almost perfect linear correlation between WBGT and heart rate. We propose WBGT can be the most applicable index for evaluating heat stress in this climate.  

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