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Background and purpose: High concentrations of respirable particles may cause high incidence of respiratory diseases and mortality in public populations and in particular in public transportation workers. Epidemiological exposure studies showed that respirable particles that emitted from traffic sources have more potential effects on more incidence of hospitalization or mortality caused by cardiovascular diseases. In this study personal exposures of bus drivers to respirable particles (PM10) and factors that caused high personal exposure were studied in Sari city.
Materials and Methods:In this study, a calibrated real time monitor (MicroDust Pro) with a personal sampling pump with 2 lit/min flow rate were used to measure Sari’s bus drivers personal exposure to PM10 concentrations on 3 main routs. This study was carried out during a one calendar year and all possible effective factors on personal exposure were recorded in a questionnaire.
Results:The mean personal exposures to PM10 concentrations among bus drivers were varied in different months. Exposure to PM10 concentrations were higher in autumn and winter and increased to 300µgm-3 in some days. Personal exposures to these particles were increased in the evening and on high traffic flow routs. Other factors such as rainy weather and temperature, number of passengers, bus' model year, picking up and dropping off the passengers were the most effectiveg factors on driver's personal exposures.
Conclusion:Bus drivers' exposure to respirable particles PM10 in Sari was varied in different time. It was due to entrance of outdoor particulate air pollutants into the bus during the picking up and getting off the passengers and resuspension of settled fine particles.

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Background and purpose: Heat is a common type of energy that is produced during industrial processes in many work places. Workers who are working in hot areas may be exposed to heat stress. The aim of this study is to evaluate the effect of a designed cool spot on reduction of Mean Radiation Temperature (MRT) and Wet Bulb Glob Temperature index (WBGT) on a group of furnace workers.
Materials and methods: First, MRT and WBGT indices were measured to evaluate heat stress in a furnace workplace. Then a suitable cool spot was designed and constructed using a double layer insulator. Finally MRT and WBGT were measured and then compared between inside and outside cool spot simultaneously to ascertain the effect of cool spot on control of heat stress.
Results: We found that mean MRT (43.8 ◦c) and mean WBGT index (29.5 ◦c) were both higher than threshold limit value (28 ◦c) recommended by ÂÇGÏH in workers' position. There was a significant difference between inside and outside cool spot in mean WBGT (22.8 vs. 29.6 ◦c) and mean MRT (28. 6 vs. 43.8 ◦c).
Çonclusion: Furnace workers who are exposed to radiation and convection heat may suffer from heat stress and we found that a cool spot in workplace is a suitable and feasible method to reduce heat stress.

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Abstract Background and purpose: Workers' exposure to respirable silica particles especially free crystalline silica in workplace could result in some dangerous diseases such as silicosis or lung fibrosis. This study was carried out to evaluate the workers' exposure to free crystalline silica particles in some industries using the infrared spectrophotometery method. Materials and methods: In this cross sectional study respirable silica dust was collected from workers' breathing zone using personal sampling device and a cyclone separator with a PVC filter. Then samples containing silica were analyzed by infrared spectrophotometery method based on NIOSH method 7602. Results: The mean of exposure to respirable silica particles within the workers' breathing zone in four industries was considerably higher than the threshold limit value recommended by ACGIH. Workers' exposure to crystalline silica particles ranged from 0.03 mgm-3 to 0.57 mgm-3 and there was a significant difference between the mean of respirable particle concentrations within the workers' breathing zone. Conclusion: Individuals working in asphalt production, foundry, sand and gravel mining and brick manufacturing are exposed to crystalline silica particle more than the standard level. Hence, in order to prevent silica related diseases more emphasize on health and safety issues is of great importance.

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Background and purpose: High concentrations of respirable particles in both the outdoor and indoor environments are associated with adverse health effects that could reduce the performance of students. This study was carried out to investigate the indoor concentrations of respirable particle and outdoor concentrations of PM2.5 at classrooms in primary schools in Sari, north of Iran. We also evaluated the relationship between outdoor concentration of particles and other environmental factors. Materials and methods: Six primary schools located in Sari city center were selected. A size selective GRIMM particle monitor was used to measure the indoor classrooms continuous real-time particle distribution and a real time Micro Dust Pro monitor was used for outdoor measurement. Results: The maximum and minimum concentrations of indoor PM1 and PM2.5 were observed in spring and autumn, respectively. The highest level of PM10 was seen in winter. The mean indoor PM2.5 concentration in classrooms was (46.6 µgm-3) which was higher (P<0.05) than the mean outdoor PM2.5 concentration (36.9 µgm-3). Ambient temperature had a significant negative effect on indoor PM2.5 levels. Conclusion: Resuspension of indoor particles and replacement of indoor and outdoor air are amongst the most effective determinants for indoor particle concentrations.

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Background and purpose: Considerable increase on the use of electronic devices increased the rate of public occupational exposure to extremely low frequency electromagnetic fields. Assessment of exposure to these fields is highly important due to potential health hazards. This study aimed at investigating the magnetic flux emission from extremely low frequency electromagnetic fields around power lines of high voltage in Neka (north of Iran) and factors affecting the magnetic flux density.
Materials and methods: In this cross-sectional study, 50 sites around high voltage transmission lines were selected and the magnetic flux density was measured at four different distances from the lines. Humidity and temperature were measured in order to assess their impact on magnetic flux density. The extremely low-frequency magnetic field was measured using an electromagnetic field tester (model TES 1394). Statistical analysis was performed in SPSS V17 applying descriptive statistics and one-way ANOVA.
Results: The highest average magnetic flux density was at the 400 kV power transmission line (2.11 ± 1.36 µT). The average magnetic flux density was higher in the afternoon (2.55 µT) compared with that in the morning. The average values for magnetic flux density under the pylon and between two pylons were 1.18 ± 0.75 and 2.55 ± 1.42 µT, respectively. Magnetic flux density decreased by increasing distance from the wire and the environment moisture.
Conclusion: The average magnetic flux density was lower than the standards set by the international commission on non-ionizing radiation protection and American Conference of Governmental Industrial Hygienists. Hence, the health effects would be negligible.
 

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Background and purpose: Imbalance between low oxygen supply and oxygen demands determines organ hypoxia causing oxidative stress and finally lead to cell death. Compounds with antioxidant activity are able to exhibit antihypoxic property. Allium sativum has distinctive antioxidant activities, but to the best of our knowledge, there is no reports on the protective effect of flower of this plant against hypoxia. In this study, antihypoxic activities of this plant were evaluated.
Materials and methods: Protective effects of A. sativum flower methanolic extract against hypoxia-induced lethality in mice were evaluated by three experimental models. Analysis of variance was performed followed by Newman-Keuls multiple comparison test.
Results: Considerable protective activities were established in all models. Antihypoxic activity was pronounced in asphyctic model. A. sativum flower methanolic extract showed the same activity of the positive control; phenytoin, at 125 mg/kg (P>0.05). At 250 mg/kg it was significantly higher than phenytoin (P<0.001). Compared to control group, in haemic model, the extract significantly prolonged survival time in a dose dependent manner. At 125 mg/kg, the extract was capable of keeping the mice alive for 31.20±5.68 min (P<0.001). At 62.5 mg/kg, it prolonged survival time (P<0.05). In circulatory model, the extract at 125 mg/kg significantly prolonged survival time (P<0.05) but was not found to be effective at 62.5 mg/kg (P>0.05).
Conclusion: Methanolic extract of A. sativum flower demonstrated strong protective effects against hypoxia in all three models.
 

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 Background and purpose: Hypoxia occurs in ischemia and heart attack, and leads to death. It involves production of reactive oxygen species. Antioxidants exhibit antihypoxic properties. Ferula persica has distinctive antioxidant activities. Nothing is known about the protective effect of this plant against hypoxia-induced lethality in mice.
Materials and methods: Protective effects of methanolic extract of F. persica aerial parts and roots against hypoxia-induced lethality in mice were evaluated by experimental models of hypoxia, asphyctic, haemic, and circulatory.
Results: Aerial parts showed a very good activity in asphyctic model and at 62.5 mg/kg the extract prolonged survival time (P< 0.05). At 250 mg/kg it showed the same activity as phenytoin. Root extract at 125 mg/kg prolonged survival time (P<0.001). Significant differences were seen between the effects of two extracts in all tested doses, but aerial parts were found to be stronger than root extract. In haemic model, aerial parts and roots showed similar activity in same doses (P>0.05). They showed the same activity as propranolol (P>0.05). Both extracts showed high activity in circulatory model and at 62.5 mg/kg they prolonged survival time (P<0.001).
Conclusion: The extracts showed protective effects against hypoxia in all tested models. Presence of polyphenols in this plant may be a proposal mechanism for its antihypoxic activities.