[Evaluation of occupational exposure to benzene and toluene among workers in two tire manufacturing factories]

Semi automated processes of Iranian tire manufacturing factories lead to significant occupational exposures to benzene and toluene compounds. This study was conducted to evaluate the magnitude and risk of workers exposures. Personal monitoring of 100 workers [10 groups] was performed using NIOSH method No.1501 in two tire manufacturing factories in Tehran city.Workplace atmospheric conditions were measured on sampling days. Semi quantitative risk assessment [COSHH] was carried out using questionnaire and respective matrix. Data were analyzed using t-test, correlation coefficient, linear regression and one-way ANOVA. Quantitative values were reported as mean +/- standard error. Age, work experience and atmospheric parameters had no significant statistical difference in two factories. Occupational exposures to benzene and toluene were 1.09 +/- 0.18, 1.88 +/- 0.19 and 2.07 +/- 0.30, 3.20 +/- 0.39 ppm in factories A and B that showed significant increase in B factory and inverse significant correlation with air relative humidity. Exposure to high risk of benzene and medium risk of toluene were 10, 14 and 10, 16 percent of workers in factories A and B, respectively. The correlation between occupational exposure and COSHH assessment was significant. occupational exposure to benzene in tire manufacturing personnel was higher than Iranian standard, therefore, improvement of work conditions using appropriate control measures including automated processes and setting of air relative humidity is recommended. COSHH assessment can be used as a simple, cheap and quick method in workers' health promotion. Control of personnel exposure through ongoing training is imperative

[ possibility of applying less tracer gas in ASHRAE-110-95 method of hood performance test]

A considerable amount of sulfur hexafluoride is applied to evaluate the performance of each laboratory hood according to ASHRAE-110-95 method.SF [6] is extremely hostile to environment and expensive. In present work, the possibility of conducting this method of hood performance test with less volume of SF [6] was investigated. The performance of a laboratory hood was evaluated using ASHRAE110-95 standard method at three different ventilation capacity as well as three different volumetric flow rates of injected SF 6 while a mannequin was located at the front of hood. Face velocity was measured 180 times using a thermal anemometer TA-2 model.Air flow was visualized through injecting low and high volume of smokes at 18 tests. Sulfur hexafluoride was injected at three different volumetric flow rates of 2, 3 and 4 lit / min.The occupational exposure of a hypothetic hood operator was determined 27 times through direct reading. The average and standard deviation of face velocity at hood inlet were 0.42 +/- 0.04, 0.6 +/- 0.07, 0.7 +/- 0.11 m / s respectively, ranging from 0.36-1.1 m / s. the studied hood did not have an acceptable performance when tested with high volumes of smoke, but it did have an acceptable performance while it was tested with low volumes of smoke. The application of ASHRAE 110-95 hood performance test with smaller volume of tracer sulfur hexafluoride gas is not recommended.