Search

The wide use of subway system by citizens underlines the importance of hygienic issues including indoor air pollution in these public places especially in metro stations. The aim of this study was to investigate the bacterial contamination in indoor and outdoor air of two metro stations (Imam Khomeini and Sadeghiyeh stations) in Tehran subway system. In this cross sectional study, three sampling locations were selected in each station. Also, sampling was conducted in indoor air of two types (old and new) of trains. The range of bacterial colony count was 35-1501 CFU/m³. Maximum and minimum bacterial contamination levels in Imam Khomeini and Sadeghiyeh platform stations were averagely 1073 CFU/m³ and 242 CFU/m³, respectively. 14 bacterial species and genera were isolated; among them the dominant species were Staphylococcus epidermidis, Micrococcus luteus and Bacillus spp. Results showed that bacterial concentrations in indoor air were higher than the outdoor air; also the bacterial counts correlated significantly with number of the passengers (p<0.001) and air temperature (p<0.001). [ABSTRACT FROM AUTHOR]

The possibility of linear alkyl benzene solfunate (LAS) photocatalytic degradation through application of TiO2 nanoparticles was investigated. 10(mg/L) of LAS has been affected by either UV or TiO2 and simultaneous use of both of them in separated experiments. Moreover, the effect of initial concentrations of LAS and TiO2, pH, present various anions and different UV power was studied to determine the optimal operating conditions for LAS degradation in water. The amount of mineralization of LAS was reported by measuring the primary and final COD of the solution that was irradiated under optimized conditions. Maximum degradation was obtained at acidic pH, 50 mg/L of TiO2 and 30 minute irradiatign, time. It was also shown that 99.5% of LAS was degraded in optimal conditions. Kinetic analysis indicated that photo catalytic degradation rates of LAS can be approximated by pseudo-first order model. Measuring the initial and final COD of illuminated solution under optimized conditions, indicated that almost complete mineralization of LAS was occurred. Based on the results, UV/TiO2 process may be effectively applied in LAS removal in low concentrations but this process is not economically efficient in high concentrations. [ABSTRACT FROM AUTHOR]

Arak waste stabilization pond facilities consist of two stabilization pond systems, module 1 and module 2. The existing facilities have had several problems in their operation. The objectives of this research were to evaluate the performance of stabilization ponds in wastewater treatment of the city of Arak, because of several problems in their operation, and to prepare a scheme of its upgrading, if necessary. Within the period of May to September 2007, analyses were carried out for both raw and treated wastewaters. Results of these investigations showed that the average effluent concentrations of BOD5, COD and SS taken from primary and secondary facultative ponds of module 1 were 91.5, 169, 114; and 70, 160, 123 mg/L, respectively. These results indicated that the effluent of the primary facultative ponds of module 1 were complied with the Iranian treated wastewater standards for agricultural reuse in terms of BOD5 and COD concentrations; hence the secondary facultative ponds could be changed to other primary facultative ponds in order to increase the capacity of wastewater treatment plant. For module 2, BOD5, COD, and SS average concentrations of treated wastewater for the secondary and tertiary facultative ponds were obtained as 69, 101, 77; and 76, 127, 78 mg/L, respectively. Thus the effluent of the secondary facultative pond was complied with the considered standards in terms of all studied parameters. Consequently, the tertiary facultative pond could be changed to other secondary facultative pond to upgrade both the quality and the quantity of treated wastewater. [ABSTRACT FROM AUTHOR]

In this research the application of Nanosil containing hydrogen peroxide and silver was studied in disinfecting swimming pool water and it's Environment. The effect of the disinfectant on Candida albicans (ATCC No. 10231), Aspergillus niger (ATCC No. 16404), Pseudomonas aeruginosa (ATCC No. 9027), Serratia marcescens (PTCC No. 1111), Klebsiella pneumoniae (ATCC No. 10031) and Staphylococcus aureus (ATCC No. 29737) ) was evaluated. The main objective of this experiment was to determine the effective dose of Nanosil which could be used for disinfecting the environment of swimming pools and other surface area. Then, the effectiveness of Nanosil was studied in two private and one public swimming pools. Heterotrophic plate count, thermotolerant coliforms, Pseudomonas aeruginosa and Staphylococcus aureus were monitored as the target microorganisms in disinfection practice According to the result of this study, it is recommended to apply the Nanosil with the concentration of >3% (30000 mg/L) for contact time of 30 min or more for practical disinfection in swimming pools environment. The application of Nanosil in real conditions of two private and one public swimming pools indicated that the acceptable microbial quality is also achievable if the disinfectant residual concentration would be as high as 20 mg/L in swimming pool water. [ABSTRACT FROM AUTHOR]

Background: Antibiotic-resistant bacteria (ARB) usually enter water sources in different ways, such as via municipal and hospital wastewaters. Because conventional technologies used to treat water inefficient in removing these contaminants (especially antibiotic-resistant genes; ARGs), these contaminants easily enter drinking water distribution networks and pose serious threats to consumers' health. This study's main purpose is to systematically investigate the effect of chlorine disinfection on ARGs in drinking water supply systems. This study could play an important role in elucidating the effect of chlorine disinfection on ARGs., Methods: The systematic review outlining this protocol will be performed according to the Collaboration for Environmental Evidence (CEE) guidelines. The main question is, "what is the effect of chlorine disinfection on ARGs in drinking water supply systems?" For this purpose, the articles will be considered, in which chlorine's effect on ARGs is investigated. The search includes electronic resources, grey literature, and related websites. Electronic resources include Scopus, PubMed, Embase, Web of Science Core Collection, and Science Direct. After the final search, the obtained articles will be collected in the reference management software (Endnote X8). Upon removing the duplicate articles, the first stage of article screening will be performed based on the title and abstract the articles. In the second stage, the articles obtained from the first screening stage will be screened based on the full text of the articles based on the eligibility criteria. Then, two members of the expert team extract the data. To assess the validity of the articles, bias sources will be determined by an expert team. Biases will be defined according to the criteria designed by Bilotta et al. Finally, a narrative synthesis will be performed for the extracted data; if appropriate data are available, quantitative analysis will also be performed., (© 2022. The Author(s).)

Background: Due to the increasing rate of hospital-acquired infections, it is essential to select appropriate disinfectant agents. In this study, the efficacy of hospital disinfectants against nosocomial infection pathogens was compared., Methods: High level disinfectants (Steranios 2%, Deconex HLDPA, and Microzed Quatenol) were tested for their antibacterial effects by determining their minimum inhibitory (MIC) and minimum bactericidal concentrations (MBC) against Enterococcus faecalis ATCC 29212 and Burkholderia cepacia ATCC 10673., Results: E. faecalis, as gram-positive bacterium, was more susceptible to high level disinfectants compared to gram-negative B.cepacia. The MIC = MBC values of 2% Steranios, Deconex HLDPA and Microzed Quatenol against E. faecalis and B.cepacia were 0.31, 9.77, 2.2 mg/L and 9.8, 78.13, 70.31 mg/L, respectively., Conclusions: According to the findings of this study, the most effective disinfectants against both E. faecalis and B.cepacia were Steranios 2%, Microzed Quatenol, and Deconex HLDPA in order. Considering the importance of these bacterial strains in healthcare-associated infections, the use of these effective disinfectants is recommended in the hospitals.

Background: Skin cancer attributed to sunlight exposure has an increasing trend worldwide, resulting in increased problems for healthcare services. This study aimed to evaluate the health safety practices of high school students in Saveh, Iran according to a sun protection guideline produced locally for Iran., Method: This cross-sectional study was done in 31 government and private high schools of Saveh, a central city of Iran. A sun protection questionnaire was designed in accordance with Iran sun protection guideline which has been developed based on the World Health Organization and US Environmental Protection Agency guidelines. The questionnaire consists of four sections of demographic information, knowledge, attitude, and protection behavior. A total of 504 students were selected by simple random sampling method. Pearson correlation coefficient and multiple linear regression analysis were used to assess the correlation between knowledge, attitude and behavior of the participants., Results: The mean score of the students' knowledge, attitude, and behavior regarding harmfulness of ultraviolet radiation was 50.79 ± 14.64, 60.41 ± 15.04, and 45 ± 11.59, respectively. A significant association was observed between attitude and knowledge, behavior and knowledge as well as attitude. There was a significant correlation between sex and protective behaviors, sex and knowledge (p ≤ 0.001), and education level and knowledge (p = 0.002)., Conclusion: students who protected themselves from sunlight less than others believed that their protection level was adequate. Health concerns related to sun exposure suggest the need for increasing the student's awareness in sun protection area. As behavior is influenced by cultural aspects, implementation of the current guideline can be effective in reducing the health effects of sun exposure.

Background: In the Gaza strip, diarrhea is one of main reasons for children visiting primary healthcare centers. Hence, we investigate predictors of the diarrheal illness and health care-seeking behavior among different age groups., Methods: This community-based cross-sectional survey was conducted from August 2017 to June 2018 among 1857 households. A pretested structured questionnaire included information about socio-demographic, sanitation, hygiene, source of water, diarrheal illness, and seeking healthcare in households was administered to head of household. To achieve representativeness for the five Gaza's governorates, a cluster random sampling was applied., Results: Of the 1857 household's heads, 421 (22.7%) reported an episode of diarrhea during the 48 h preceding the interview resulting an overall prevalence rate of 3.8 per 100 individuals. The prevalence of diarrhea was statistical significant greater in males (5.4/100) compared to females (1.3/100) in all age groups (p <  0.05). Socio-demographic, economic, water, sanitation, and hygiene factors were predictors of the diarrheal illness and seeking of non-professional healthcare for diarrhea illness treatment among. A transition behavior from professional to non-professional and vice versa in seeking healthcare in each diarrheal episode was found., Conclusions: We recommend improving the status of water, sanitation, and hygiene in the Gaza strip's households to reduce diarrhea among the population of Gaza strip. Community sensitization about the importance of seeking care at primary health centers because treatment of children is available for free or in low costs.

The majority of anthraquinone dye released to the environment come from antrapogenic sources. Several techniques are available for dyes' removal. In this study removal of reactive blue 29 (RB29) by an advanced oxidation process sequenced with single wall carbon nanotubes was investigated. Advanced oxidation process was optimized over a period of 60 minutes by changing the ratio of acetic acid to hydrogen peroxide, the compounds which form peroxy acid. Reduction of 20.2% -56.4% of reactive blue 29 was observed when the ratio of hydrogen peroxide/acetic acid/dye changed from 344/344/1 to 344/344/0.08 at different times (60, 120 and 180 min). The optimum ratio of acetic acid/hydrogen peroxide/dye was found to be 344/344/0.16 over 60 min. The resultant then was introduced for further removal by single wall carbon nanotubes(SWCNTs) as adsorbent. The adsorption of reactive blue 29 onto SWCNTs was also investigated. Langmuir, Freundlich and BET isotherms were determined and the results revealed that the adsorption of RB29 onto SWCNTs was well explained by BET model and changed to Freundlich isotherm when SWCNTs was used after the application of peroxy acid. Kinetic study showed that the equilibrium time for adsorption of RB 29 on to SWCNT is 4 h. Experiments were carried out to investigate adsorption kinetics, adsorbent capacity and the effect of solution pH on the removal of reactive blue29. The pseudo-second order kinetic equation could best describe the sorption kinetics. The most efficient pH for color removal (amongst pH=3, 5 and 8) was pH= 5. Further studies are needed to identify the peroxy acid degradation intermediates and to investigate their effects on SWCNTs.

Sonolysis and photochemical degradation of different compounds such as chlorinated aliphatic hydrocarbons are among the recent advanced oxidation processes. Perchloroethylene is one of these compounds that has been mainly used as a solvent and degreaser. In this work, elimination of perchloroethylene in aqueous solution by ultrasonic irradiation, andphotochemical oxidation by ultra violet ray and hydrogen peroxide were investigated. Three different initial concentrations of perchloroethylene at different pH values, detention periods, and concentrations of hydrogen peroxide were investigated. Head space gas chromatography with FID detector was used for analyses of perchloroethylene. This research was performed in 9 months from April through December 2011.Results showed that perchloroethylene could be effectively and rapidly degraded by ultrasonic irradiation, photochemical oxidation by ultra violet ray, hydrogen peroxide and a combination of these methods. Kinetics of perchloroethylene was strongly influenced by time, initial concentration and pH value. Degradation of Perchloroethylene increased with decrease in the initial concentration of perchloroethylene from 0.3 to 10 mg/L at all initial pH. The results showed an optimum degradation condition achieved at pH = 5 but did not affect significantly the perchloroethylene destruction in the various pH values. Kinetic modeling applied for the obtained results showed that the degradation of perchloroethylene by ultrasound and photo-oxidation followed first order and second order model. The percentage of removal in the hybrids reactor was higher than each of the reactors alone, the reason being the role of hydroxyl radical induced by ultrasound and photochemical reaction.

The aims of the present study were to provide quantitative data on the impact of air pollution on the health of people living in Tehran city, the most populated city of Iran. The approach proposed by the World Health Organization (WHO) was applied using the AirQ 2.2.3 software developed by the WHO European Centre for Environment and Health, Bilthoven Division. Concentrations of ozone, nitrogen dioxide, sulfur dioxide and particulate matter of aerodynamic diameter ≤ 10 μm (PM10) were used to assess human exposure and health impacts in terms of attributable proportion of the health outcome, annual number of excess cases of mortality for all causes, and cardiovascular and respiratory diseases. The annual average of PM10, SO2, NO2 and O3 in Tehran were 90.58, 89.16, 85 and 68.82 μg/m3, respectively. Considering short-term effects, PM10 had the highest health impact on the 8,700,000 inhabitants of Tehran city, causing an excess of total mortality of 2194 out of 47284 in a year. Sulfur dioxide, nitrogen dioxide and ozone caused about, respectively, 1458, 1050 and 819 excess cases of total mortality. Results indicate that the magnitude of the health impact estimated for the city of Tehran underscores the need for urgent action to reduce the health burden of air pollution.