Background and aim: The chromium Mist generator is an essential tool for research and for making evidence-based recommendations in evaluating air pollution and its control systems. The purpose of this study was to design and construct a homogeneous chromium Mist generator and to look at the effects of factors such as sampling height and distance between samplers in side-by-side sampling on the chromium Mist sampling method.Material and Methods: First we developed a Mist generator, using a chromium electroplating bath in pilot scale. Concentrations of CrO3 and sulfuric acid in plating solution were 125 g L-1 and 1.25 g L-1, respectively. To set up permanent air sampling locations, a Plexiglas cylindrical chamber (75 cm height, 55 cm i.d) was installed as the bath overhead. Sixty holes were made on the chamber in 3 rows (20 in each row). The distance between rows and holes was 15 and 7.5 cm, respectively. Homogeneity and the related factors were studied using a side-by-side air sampling method. Forty-eight clusters of samples were collected on polyvinyl chloride (PVC) filters contained in sampling closed-face cassettes. Cassettes were located 35, 50, and 65 cm above the solution surface with < 7.5 and/or 7.5-15 cm distance between heads. All samples were analyzed by the NIOSH method 7600.Results: ANOVA tests showed no significant differences between locations in side-by-side sampling (P=0.82) or between different sampling heights or sampler distances (P=0.86 and 0.86, respectively). However, there were notable differences between means of coefficients of variation (CV) in various heights and distances.Conclusion: We conclude that the most chromium Mist homogeneity could be obtained at a height of 50 cm from the bath solution surface and with a distance of < 7.5 cm between samplers.

BACKGROUND AND OBJECTIVE: Personal protective equipments (PPE) are common equipments for control of workers exposure to harmful agents in work environment. Regarding to the critical role of the filter collection efficiency under hazardous conditions such as exposure to carcinogen materials, this study was performed to determine the effect of different factors on efficiency of respirator filters in removing hexavalent chromium Mist.METHODS: In this quasi-experimental study, homogenous chromium Mist at different conditions (concentration 1.25 and 2.5 mg/m3, relative humidity 50 and 80%, and temperature 0-5 and 35-40 oC) passed through two types of respirator filters (MSA and Spasciani). All samples (n=384) were collected, using NIOSH 7600 test method at upstream and downstream of respiratory filters, simultaneously and analyzed, using an atomic absorption spectrometer and inductively coupled plasma (ICP), respectively.FINDINGS: Although type of filter had significant effect on hexavalent chromium Mist removal, the ANOVA test results indicated that the increase of chromium Mist concentration and relative humidity resulted a significant decrease in removal efficacy 0.53% and 0.42%, respectively (p<0.001). The temperature had not significant effect on filter efficiency.CONCLUSION: Increase of hexavalent chromium Mist concentrations and relative humidity has significant negative effect on collection efficiency of respirator filters.