Evaluation of Seasonal Variation on the Health Risks Using the Quantitative Microbial Risk Assessment Approach in a Wastewater Treatment Plant in Hamadan, Iran.

BACKGROUND: Wastewater treatment plants (WWTPs) are a source of airborne bacterial contamination that can pose health risks to staff. The aim of this study was to evaluate seasonal variations in the health risks of exposure to Staphylococcus aureus bioaerosols using the quantitative microbial risk assessment (QMRA) approach in a WWTP in Hamadan, Iran. STUDY DESIGN: This was a descriptive cross-sectional study. METHODS: This study determined the emission concentrations of S. aureus bioaerosols in summer and winter. Then, the health risks of three exposure scenarios (the worker, field engineer, and laboratory technician) were evaluated using the QMRA approach. The bioaerosol samples were collected every 12 days in both summer and winter of 2021 with a nutrient agar using a single-stage cascade impactor (Quick Take 30, SKC Inc.) in both outdoor and indoor environments. RESULTS: The results demonstrated that in both seasons, S. aureus bioaerosol concentrations in outdoor and indoor environments were below the standard established by the American Conference of Governmental Industrial Hygienists (500 CFU/m3 ). While in summer, the annual infection risks and the disease burden for the three exposure scenarios in both outdoor and indoor environments were higher than the United States Environmental Protection Agency (≤10-4 pppy) and the World Health Organization (WHO) (≤10-6 DALYs pppy-1) benchmarks, respectively. CONCLUSION: The findings provided high health risks for staff in the three exposure scenarios of an indoor environment, which should not be ignored, as well as emphasizing the use of the QMRA approach to estimate health risks caused by occupational exposure to bioaerosols and taking executive measures to protect staff working in the WWTPs.

A needle trap device packed with MIL-100(Fe) metal organic frameworks for efficient headspace sampling and analysis of urinary BTEXs.

The aim of this study was to develop a new method for the determination of benzene, toluene, ethylbenzene and xylene isomers (BTEXs) in urine samples. In this method, MIL-100(Fe)@Fe3 O4 @SiO2 metal-organic framework was synthesized, characterized and packed inside a needle trap device (NTD) as a sorbent for headspace extraction of unmetabolized BTEXs from urine samples followed by gas chromatography (GC) analysis. The GC device was equipped with a flame ionization detector (FID). The results showed that the optimal extraction time, extraction temperature and salt content were 60 min, 30°C and 5%, respectively. Also, the optimal desorption time and temperature were determined to be 1 min and 250°C, respectively. The limits of detection and quantification of the analytes of interest were in the ranges 0.0001-0.0005 and 0.0003-0.0014 µg ml-1 , respectively. The intra- and inter-day repeatability were <7.6%. The accuracy of the measurements in urine samples was in the range 7.1-11.4%. The results also demonstrated that the proposed NTD offered various advantages such as having high sensitivity and being inexpensive, reusable, user friendly, environmentally friendly and compatible for use with the GC device. Therefore, it can be efficiently used as a MIL-NTD for the extraction and analysis of unmetabolized BTEXs from urine samples.

The Past and Future Trends of Heat Stress Based On Wet Bulb Globe Temperature Index in Outdoor Environment of Tehran City, Iran.

BACKGROUND: The workers who are working in the open and warm environments are at risk of health effects of climate and heat changes. It is expected that the risk is increase with global warming. This study aimed to investigate the changes of Wet Bulb Globe Temperature (WBGT) index in the past and to predict their trend of future changes in Tehran, capital of Iran. METHODS: The meteorological data recorded in Tehran, Iran during the statistical period between 1961 and 2009 were obtained from the Iran Meteorological Organization and based on them, WBGT index was calculated and processed using Man-Kendall correlation test. RESULTS: The results of Man-Kendall correlation test showed that the trend of changes of annual mean WBGT during the statistical period under study (1961-2009) has been significantly increasing. In addition, the result of proposed predictive model estimated that an increase of about 1.55 degree in WBGT index will be seen over 40 years from 2009 to 2050 in Tehran. CONCLUSION: Climate change in Tehran has had an effect on person's exposure to heat stresses consistent with global warming.

Noise annoyance due to construction worksites.

BACKGROUND: Noise pollution can contribute to adverse health effects in humans. Noise annoyance and related problems, caused by noise emission during the progress of building construction, have become increasingly important. These problems can influence the exposed workers, as well as vicinity residents. The goal of the present study was to assess the noise annoyance due to noise from construction worksites among residents of Hamadan City (west of Iran). METHODS: In this cross-sectional study, 20 construction worksites and 140 near vicinity residents were selected. The main sources of construction worksite noise were diesel power generators, cutting and welding processes, heavy machinery (such as trucks) and transport of materials. Ambient noise levels were measured using a calibrated sound level meter, at each home of the residents included in the study. A noise annoyance questionnaire was employed for annoyance assessment. RESULTS: The majority of subjects had very high annoyance (87.1%). The mean and SD of ambient levels were 74.57±7.12 dB (A) which exceeded the acceptable recommended level for residential areas. The most common problems among the participants were disturbance in sleep, difficulty in reading and distraction. Results showed significant relationship between noise annoyance and some factors including residing which floors had highest annoyance (F=13.22, P<0.001) and ambient noise (F=11.313, P<0.001). CONCLUSIONS: High levels of noise annoyance among near vicinity residents who are affected by construction activities. This means that construction activities and other noise related sources should be regarded as the major source of ambient noise leading to noise annoyance.