Spatial traffic noise pollution assessment – A case study

Objectives: Spatial assessment of traffic noise pollution intensity will provide urban planners with approximate estimation of citizens exposure to impermissible sound levels. They could identify critical noise pollution areas wherein noise barriers should be embedded. The present study aims at using the Geographic Information System (GIS) to assess spatial changes in traffic noise pollution in Tehran, the capital of Iran, and the largest city in the Middle East. Material and Methods: For this purpose, while measuring equivalent sound levels at different time periods of a day and different days of a week in District 14 of Tehran, wherein there are highways and busy streets, the geographic coordination of the measurement points was recorded at the stations. The obtained results indicated that the equivalent sound level did not show a statistically significant difference between weekdays, and morning, afternoon and evening hours as well as time intervals of 10 min, 15 min and 30 min. Then, 91 stations were selected in the target area and equivalent sound level was measured for each station on 3 occasions of the morning (7:00–9:00 a.m.), afternoon (12.00–3:00 p.m.) and evening (5:00–8:00 p.m.) on Saturdays to Wednesdays. Results: As the results suggest, the maximum equivalent sound level (Leq) was reported from Basij Highway, which is a very important connecting thoroughfare in the district, and was equal to 84.2 dB(A), while the minimum equivalent sound level (Leq), measured in the Fajr Hospital, was equal to 59.9 dB(A). Conclusions: The average equivalent sound level was higher than the national standard limit at all stations. The use of sound walls in Highways Basij and Mahallati as well as widening the Streets 17th Shahrivar, Pirouzi and Khavaran, benchmarked on a map, were recommended as the most effective mitigation measures. Additionally, the research findings confirm the outstanding applicability of the Geographic Information System in handling noise pollution data towards depicting noise pollution intensity caused by traffic

Investigation of heat stress and heat strain in outdoor workers: a case study in Iran

Heat stress is an important and serious threat at work and is a particular concern in outdoor occupational environments. This study aims at comparing heat stress and heat strain at different outdoor groups, examining the protective and adaptive actions which were done by workers and also provi services to them by government or employer to reduce heat load. This cross–sectional study was conducted in the hottest days of the summer 2015 in Shabestar, Iran and 53 healthy men in nine occupational groups including concrete makers, porters, construction, waste site and road making workers, stonemasons, farmers, traffic officers, and street vendors participated. A set of physiological parameters, like heart rate, blood pressure, skin temperature and etc., WBGT index details and some of the adaptive and protective parameters were measured and monitored simultaneously at different times of the day. The study finds that heat exposure in outdoor workplace is prevalent and WBGT TWA/TLVave is less than 1 in some groups like stonemasons, waste site workers, traffic officers and street vendors whereas in other studied occupations, it is more than 1.This matter is compounded by the fact that the provision of health services by employers or local government was limited, and almost all of the participants had poor or insufficient access levels to public health and welfare services. This study confirms the necessity of interventions by a range of factors, such as government plans, improvement of services in the prevention of heat stress, and planning training courses for outdoor workers to build their knowledge of heat stress

A Model to Determine the Level of Serum Aldosterone in the Workers Attributed to the Combined Effects of Sound Pressure Level, Exposure Time and Serum Potassium Level: A Field-Based Study

Background: Occupational exposure to excessive noise is one of the biggest work-related challenges in the world. This phenomenon causes the release of stress-related hormones, which in turn, negatively affects cardiovascular risk factors. Objectives: The current study study aimed to determine the level of workers’ serum aldosterone in light of the combined effect of sound pressure level, exposure time and serum potassium level. Methods: This cross-sectional, descriptive, analytical study was conducted on 45 workers of Gol-Gohar Mining and Industrial Company in the fall of 2014. The subjects were divided into three groups (one control and two case groups), each including 15 workers. Participants in the control group were selected from workers with administrative jobs (exposure to the background noise). On the other hand, participants in the case groups were selected from the concentrator and pelletizing factories exposed to excessive noise. Serum aldosterone and potassium levels of participants were assessed at three different time intervals: at the beginning of the shift and before exposure to noise (7:30 - 8:00 AM), during exposure to noise (10:00 - 10:30 AM), and during continuous exposure (1:30 - 2:00 PM). The obtained data were transferred into SPSS ver. 18. Repeated measures analysis of variance (ANOVA) was used to develop the statistical model of workers’ aldosterone level in light of the combined effect of sound pressure level, exposure time, and serum potassium level. Results: The results of the final statistical model to determine the level of serum aldosterone based on the combined effect of sound pressure level, exposure time and serum potassium level indicated that the sound pressure level had a significant influence on the human’s serum aldosterone level (P = 0.04). In addition, the effects of exposure time and serum potassium on aldosterone level were statistically significant with P-values of 0.008 and 0.001, respectively. Conclusions: The obtained model in the study revealed that the results of predictive models to determine aldosterone level were very similar to real values; therefore, the obtained values of this model were largely in line with the ones obtained from the field

Development of an observational-perceptual heat strain risk assessment (OPHSRA) index and its validation

Background The thermal strain can be measured using subjective methods without the use of sensitive equipment. The purpose of the present study was the development and validation of an observational - perceptual heat strain risk assessment (OPHSRA) method. Methods This cross-sectional study, in 2019, was performed. At first, an observational-perceptual questionnaire was designed using effective items in producing heat strain. Then, the reliability and validity of the questionnaire were examined. Later, 201 male workers were asked to perform the routine tasks for 90 min under various climatic conditions after resting in a cool room. At the end of the activity, the tympanic temperature of the subjects was accurately measured. Also, the designed questionnaire was completed by researchers and participants. Then, the effect coefficients of the items were calculated and used for developing the novel index. At final, the index validity was investigated. Results The values of the content validity ratio (CVR), content validity index (CVI), and Cronbach's coefficient alpha (alpha) of the designed questionnaire with 16 questions were equal to 0.793, 0.913, and 0.910, respectively. The results indicated that environmental, job, administrative, and clothing items assessed by the questionnaire with the coefficients of 0.860, 0.658, 0.783, and 0.566 had significant effects on the thermal strain, respectively. These coefficients were exploited to develop the index. The result revealed that the OPHSRA index justified 69% of the variations of the tympanic temperature (R-2 = 0.69). Conclusion The novel index developed by the questionnaire had an acceptable validity. Therefore, this index can be used for estimating the risk of thermal strain in a variety of thermal conditions

Assessment of the Effects of Different Sound Pressure Levels on Distortion Product Otoacoustic Emissions (DPOAEs) in Rats

Excessive exposure to noise can lead to Noise-Induced Hearing Loss. Otoacoustic emissions affect the microscopic biomechanical activities of healthy outer hair cells. The present study aimed at assessing the influence of various sound pressure levels on Distortion Product Otoacoustic Emissions (DPOAEs) in rats. To this end, 27 adult male rats with an age range of 3 to 4 months and a weight of 200 ± 50 g were randomly divided into nine groups of three. Three groups were considered as the control groups and the rest (i.e. Six groups) as the case groups. Rats of the case groups were exposed to sound pressure levels of 85, 95, and 105 dBA. White noise was used as the noise to which the rats were exposed. The signal to noise ratio (SNR) of otoacoustic emissions of rats’ ears was measured at different frequencies in an acoustic room using a DPOAE machine (4000 I/O manufactured by Homoth of Germany). The collected data were analyzed by the use of Statistical Package for Social Sciences (SPSS) version 18. The results of SNR measurement indicated that over 90% of the data had SNR values of 6dB or more. Furthermore, sound pressure level had a significant negative correlation with SNR, i.e. as the sound pressure level increased, the SNR declined (p<0.001). There was also a significant negative correlation between exposure time and SNR, meaning that increase in the exposure time led to decline in the SNR (p=0.008). It is thus concluded that higher sound pressure levels result in decrease in DPOAE levels

Establishing research impact assessment in Iran: The first report from a non-high-income country

Background This study presents the first report on research impact assessment (RIA) in non-high-income countries, undertaken as a pilot initiative in 2021. Within it, we aimed to explore the feasibility of employing the ‘payback’ model for evaluating the impact of health research and enhancing the accountability of universities. We focussed on three key impact domains: ‘production of decision support documents and knowledge-based products,’ ‘implementation of research results,’ and ‘health and economic impact.’ Methods We adopted a case study approach to assess the impact of 5334 health research projects conducted by researchers from 18 universities from 2018 to 2020. Researchers were required to submit evidence related to at least one of the specified impact domains; six scientific committees verified and scored claimed impacts at the national level. Results Only 25% of the assessed projects achieved impact in at least one domain, with the production of decision support documents and knowledge products being the most reported impact. Notably, economic impact was verified in only three projects, indicating room for improvement in this area. Technology research exhibited the highest acceptance rate of claimed impact, suggesting a positive correlation between technology-focused projects and impactful outcomes. Conclusions This study demonstrates the feasibility of employing a case study approach and the ‘payback’ model to evaluate the impact of health research, even within the constraints of a moderately equipped research infrastructure. These findings underscore the potential of integrating RIA into the governance of health research in Iran and other non-high-income countries, as well as the importance of using RIA to assess the accountability of health research systems, guide the allocation of research funding, and advocate for the advancement of health research. The study sets a precedent for future assessments in similar contexts and contributes to the ongoing global dialogue on the societal impact of health research

The Role of Top Surface to Performance of Reactive T-Shape Noise Barriers

T-shape profile barriers are one of the most successful barriers among many different profiles. It has been shown that using welled diffusers on the top of T-shaped barriers makes a reactive barrier that shows better performance than that of any other used profile barriers compared with their equivalent absorbent barrier. The contribution of the top surface of reactive T-profile barriers to their efficiency in the shadow zone is discussed in this paper. The new multiple impedance discontinuity (NMID) method was used on a few multi-welled surfaces and the application of the findings on the diffuser T-profile barrier along with a descriptive theory of the welled surface effect was presented. An acceptable agreement between the result of the NMID model and BEM method for a few welled surfaces were found. The area-averaged impedance model was also used in the NMID model and it was found that this model can be a good performance indicator for a multi-welled surface. In order to explain the contribution of the top surface of a T-profile barrier, it is adequate to use the NMID model on a mixed ground equivalent to the top surface of the barrier where the source and receiver are located at near the ground where the separation of source and receiver is identical with the overall span of the cap. The effect of average admittance of top surface is dominant and the effect of the impedance discontinuity is overshadowed by this effect

Study of the effect of shape on acoustic performance of micro perforated absorbent at low frequencies

Introduction: Micro-perforated absorbents are one of the structures that are widely used nowadays. The sound absorption mechanism is performed by viscous energy losses in the cavities on the plate. In this study, the acoustic properties of non-flat perforated panels in oblique angle was investigated in numerical method. Material and Methods: This paper examined the effect of the surface shape on the micro perforated absorber performance at low frequencies (less than 500 Hz). The three-dimensional finite element method was used to predict the absorption coefficient of this group of adsorbents. Also, the results obtained from the shaped absorbents were compared with the flat micro perforated ones. After validating the numerical results, six different designs were defined as the surface shape of the micro perforated plates in the COMSOL Multiphasic, Ver. 5.3a software Results:  The results reflected the fact that the factor of the surface shape can be used as a contributing factor in lower frequencies. In general, the dented or concave shapes provide better outcomes than other flat designs and shapes and the convex or outward shapes bring the weakest results. Conclusion: To explain this function, shaping creates a phase difference and angling the sound wave and creates a variable depth behind the micro-perforated plate. It also influences the reflection process which affect the absorption coefficient