Currently, UVC radiation is used in hospitals to eliminate microorganisms and reduce adverse health effects in operating rooms (ORs) and protective environment rooms (PERs). The purpose of this study was to investigate the effect of UVC irradiation on bioaerosols in ORs and PERs. This experimental study was performed in ORs and PERs in a hospital. Bioaerosols were evaluated according to the National Institute for Occupational Safety and Health (NIOSH) standard (No. 0800). The samples were collected from indoor air of rooms before irradiation and after UVC (254 nm) irradiation for 20 and 480 minutes. The sample size of the study was determined to be 432 (216 fungi and 216 bacteria). The difference between the mean concentration of bioaerosols in the UVC radiation at two intervals (20 and 480 minutes) was significant, which indicates a decrease in the concentration of bioaerosols by increasing the duration of UVC radiation. Some bacteria, such as group B Streptococcus, Lactobacillus, and Listeria, were entirely killed after 20 minutes of irradiation,however, complete removal of the bacteria such as Staphylococcus pneumoniae and Staphylococcus saprophyticus was observed after 480 minutes of UVC irradiation. Fungi, such as Alternaria, Stofelim, and Mucor had a 100% reduction after 20 minutes of UVC irradiation, and Rhizopus and Aspergillus fumigatus showed a 100% decrease after 480 minutes of UVC irradiation. Other isolated fungi such as Cladosporium, Penicillium, Aspergillus niger, Rhodotorula, and Alternaria showed a decrease of 75%-98. 78%. The ultraviolet (UV) sensitivity of bacterial and fungal bioaerosols depends strongly on their type. The results from this study may offer an important understanding of the control of indoor bioaerosols using UVC irradiation and help abate the environmental impacts of airborne microbes.

Introduction: Humic acid (HA) is the original disinfection byproduct produced in processors in water treatment. So, removing it is necessary before water chlorination. In the present study, photodegredation of humic acid in water using Ag/ZnO nano particle under UVc irradiation in batch system was investigated.Material and Methods: Photocatalytic study was carried out to evaluate the effect of UVc (15w), irradiation time of (10-40min), pH (5-9), initial humic acid concentration of (10-50 mg/L) and Ag/ZnO dosage of (0.2-0.8 g/L) on humic acid removal. HA concentration was monitored spectrophotometrically by measuring the HA absorbance at 254 nm.Results: HA removal efficiency was obtained 88% at pH 7, Ag/ZnO dosage 0.6 g/L, initial humic acid concentration 25 mg/L and irradiation time of 40 min. The removal of HA from aqueous solution increased by increasing irradiation time and decreasing initial HA concentration. Also, the kinetic study was consistent with pseudo-first order reaction.Conclusion: The results showed that photocatalytic degredation process using Ag/ZnO nanoparticles can be used efficiently for HA removal from aqueous solutions.

Objective: The use of nanoscale particles, for instance silver nanoparticles (Ag NPs) has considerably increased recently. Since Ag NPs can be transmuted into silver ions; the toxicity and genotoxicity of these NPs along with other external factors such as ultraviolet type C (UVC) irradiation must be evaluated. In the present study, the aim was to investigate the genotoxic effects Ag NPs and UVC co-exposure on human lymphoblastoid TK6 cells. Materials and Methods: In this experimental study, Ag NPs (~20 nm) were purchased from US Research Nanomaterials Inc. and H2AX gene expression was evaluated using quantitative real time polymerase chain reaction (qRT-PCR), 1 and 24 hours post Ag NPs and UVC treatment. Results: Results showed that treatment of TK6 cells with different Ag NP concentrations without exposure to UVC can reduce H2AX gene expression, but treatment of these cells with Ag NPs in combination UVC irradiation can reduce viability that leads to a synergistic increase in the amount of H2AX gene expression. Conclusion: According to our findings, Ag NPs can act to sensitize cells to UVC radiation when used for cancer treatment. So, combination of Ag NPs and UVC irradiation could be used in radiotherapy.