Journal of Health and Safety at Work

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: Indoor air environments contain a wide variety of microorganisms such as bacteria, fungi, and viruses in which some of them can affect the human health. Filtration is considered as one of the most common methods to remove microorganisms in these environments. The purpose of current study was to investigation the neat and photocatalytic HEPA filters performance at different face velocities and various intensity of UVC light source on the reduction of airborne microorganisms.

Material and Method: After installation of the neat and photocatalytic HEPA filters in a closed–loop chamber, suspension of Staphylococcus epidermidis and Bacillus subtilis bacteria with a concentration of 107 CFU / ml were sprayed into the closed–loop chamber by nebulizer. Sampling of penetrated microorganisms from filters were performed using the NIOSH 0800 method under ambient temperature 22±3oC, relative humidity 35±5%, and different air velocity (0.1 m/s and 0.3 m/s) and UVC different radiation intensity (1 mW/cm2, 1.8 mW/cm2 and no radiation (dark)) at 30 minutes time period. penetrated microorganisms density from filters was determined in term of CFU/m3.

Result: There were no significant differences in the penetration rates of microorganisms at the dark mode between the two neat and photocatalytic HEPA filters (p>0.05). The penetration rate of bacteria was significantly decreased in the neat and photocatalytic HEPA filters at UVC radiation mode with various intensities than dark mode (p<0.05). In addition, comparison of the filters in the illuminance modes of 1 mW/cm2 and 1.8 mW/cm2 were statistically significant (P <0.05). Also, UVC radiation with the 1.8mW/cm2 illuminance compared to the 1 mW/cm2 illuminance resulted in a greater reduction in the bacterial penetration from both types of filters, which is statistically significant(p<0.05). The bacteria penetration rate dramatically increased by increasing the face velocity from 0.1 m/s to 0.3 m/s under UVC radiation at an illuminance of 1mW/cm2, 1.8mW/cm2 and as well as in no radiation mode in both types of HEPA filters (P <0.05).

Conclusion: Photocatalytic HEPA filters and increasing UVC illuminance, especially at lower surface velocities, have a significant positive effect on reducing airborne microorganisms and increasing the efficiency of HEPA filters