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Few studies have documented the air quality, noise, thermal comfort, and health risk assessment of household kitchens related to Sub-Sahara Africa. In this paper, air quality (CO and PM2.5), thermal comfort (relative humidity (RH) and temperature), noise, and health risk in urban household kitchens with kerosene-fueled stoves were presented. This study was carried out during the dry season (summer) in the Southwestern part of Nigeria. At the breathing zone, PM2.5 and CO concentrations in the assessed kitchens were measured. In addition, the noise level, RH, and air temperature in the assessed kitchens were also determined. Furthermore, an evaluation of the heat index and health risk of the exposed population to the kerosene-fueled stove kitchens was carried out. During cooking, average CO and PM2.5 concentrations were 24.77 ± 1.05 ppm and 138.10 ± 2.61 µg/m3, respectively, while the RH was 68.34 ± 0.73%, noise level was 51.14 ± 1.08 dB, and temperature was 29.86 ± 0.23 °C. The CO and noise levels were relatively slightly lower and PM2.5 was significantly higher than the thresholds recommended by World Health Organisation. In most of the kitchens, the heat index evaluation revealed the possibility of heat exhaustion, heat cramps, and sunstroke with prolonged exposure of the vulnerable group. The air quality index depicted unhealthy (CO exposure) and very unhealthy (PM2.5 exposure) while the hazard quotient (> 1) implied possible health risk concerning exposure by inhalation. Better design of kitchen with adequate ventilation and improved stoves are suggested.

The advantages of the demand control ventilation system (DCV) have been widely discussed in previous research studies. However, the literature has not addressed the benefits of DCV on controlling indoor CO2 concentration and minimizing cooling energy consumption for school buildings located in extremely hot climates. Therefore, this paper contributes to the development of DCV and mechanical ventilation systems through a comprehensive evaluation of these systems to maintain acceptable indoor air quality (IAQ) while minimizing cooling energy demands for school buildings located in the harsh hot climate of Saudi Arabia. The evaluation is based on a calibrated whole-building energy model and validated IAQ predictions using field data obtained from a school case study in Jeddah. The results of this research study confirm that hourly and sub-hourly monitoring of indoor CO2 concentration is required to ensure optimal design and operation of the ventilation systems in schools. In addition, the analyses indicate that a 13% increase in cooling energy end-use can result for any additional 0.1 students/m2 density increase in the classrooms. However, the energy penalties related to ventilation needs can be reduced by up to 25% using DCV instead of conventional mechanical ventilation systems for school buildings located in Saudi Arabia’s hot climate.

This research addresses different issues related to the ventilation and the aerosol concentration present in a metal additive manufacturing facility using Laser Powder Bed Fusion (L-PBF) machine. Performing air monitoring requires quantifying the emissions potentially generated in the different areas and during the different L-PBF process phases. A practical Indoor Air Quality (IAQ) assessment protocol is addressed in this research questioning the type of emissions to measure, and the way to collect them. As a measurement strategy for the airborne particles lower than 700 nm, real-time metrology discmini instruments were used (Testo, 1 L.min−1, Forbach, France). The particle number concentration was assessed during three operations: (i) before cleaning the room where the L-PBF machine is located, (ii) during the cleaning phase of the room, and (iii) after the cleaning phase. Without ventilation and without human activity, the background concentration level in the additive manufacturing facility was 5.103 #/cm3 either before or after cleaning. With ventilation and without human activity, the background concentration level was decreased to 4.103 #/cm3 before cleaning, and increased to 1.5.104 #/cm3 after cleaning. Besides, human activity leads to an increase in the number of suspended particles, since they passed from 5.103 #/cm3 to 1.9.104 #/cm3. Finally, a value of 105 #/cm3 was recorded on the operator during the cleaning phase and clearly, show peaks of particle number concentration. It was found that the local ventilation plays a role in the resuspension of particles from surfaces. Indeed, particles deposited on the floor are a source of exposure and hence the need for a clean room. The result section reinforces the necessity of wearing individual protective equipment during the maintenance and cleaning operations of a facility including L-PBF machine.

Background Medical simulation training requires realistic simulators with high fidelity. This prospective multi-center study investigated anatomic precision, physiologic characteristics, and fidelity of four commercially available very low birth weight infant simulators. Methods We measured airway angles and distances in the simulators Premature AirwayPaul (SIMCharacters), Premature Anne (Laerdal Medical), Premie HAL S2209 (Gaumard), and Preterm Baby (Lifecast Body Simulation) using computer tomography and compared these to human cadavers of premature stillbirths. The simulators’ physiologic characteristics were tested, and highly experienced experts rated their physical and functional fidelity. Results The airway angles corresponded to those of the reference cadavers in three simulators. The nasal inlet to glottis distance and the mouth aperture to glottis distance were only accurate in one simulator. All simulators had airway resistances up to 20 times higher and compliances up to 19 times lower than published reference values. Fifty-six highly experienced experts gave three simulators (Premature AirwayPaul: 5.1 ± 1.0, Premature Anne 4.9 ± 1.1, Preterm Baby 5.0 ± 1.0) good overall ratings and one simulator (Premie HAL S2209: 2.8 ± 1.0) an unfavorable rating. Conclusion The simulator physiology deviated significantly from preterm infants’ reference values concerning resistance and compliance, potentially promoting a wrong ventilation technique. Impact Very low birth weight infant simulators showed physiological properties far deviating from corresponding patient reference values. Only ventilation with very high peak pressure achieved tidal volumes in the simulators, as aimed at in very low birth weight infants, potentially promoting a wrong ventilation technique. Compared to very low birth weight infant cadavers, most tested simulators accurately reproduced the anatomic angular relationships, but their airway dimensions were relatively too large for the represented body. The more professional experience the experts had, the lower they rated the very low birth weight infant simulators.

Heating, ventilation and air conditioning (HVAC) systems are widely used to regulate indoor temperature and air quality of modern buildings. The central supply and exhaust system cause the dispersal and removal of bioaerosols. This study presents results from ex situ experiments conducted to a better understanding of the spatiotemporal distribution, passive dispersal and removal of fungal spores through HVAC systems. The study was conducted in a 50 square meters by 3 m high instrument room in a research building with HVAC systems. Plates with Aspergillus flavus colony were attached upside down on the edge of the ceiling vent to imitate the mildew growing. Fungal spores were released for 10 min, collected and counted by the settle plate method in 2 h. Results show that A. flavus spores dispersed to 3.6 m in 2 min and were evenly distributed in the room within 8 min. The concentration of spores decreased from 48 to 3–6 CFU/plate after 60 min and was lower than 1% after 120 min. Our results suggest that airborne fungal spores disperse and remove by HVAC systems efficiently. Without the external and internal source, the HVAC system could greatly reduce the fungal amount in the indoor air to the background level within one hour. This study provided the observed data of the transmission and retention of internal or external biological contaminants through HVAC system.

Residential areas are being increasingly impacted by wildfire smoke that causes hazardous local ambient air quality conditions. Poor outdoor air quality also exacerbates the quality of indoor air as smoke particles penetrate the building envelope or the heating, ventilation, and air-conditioning (HVAC) filtration systems. In this work, we investigate the impact of wildfire-affected poor ambient air quality on indoor air particulate matter during a wildfire episode in June 2015 in interior Alaska. We measured size-resolved (0.3–10 μm) particle number counts (PNC; numbers/cm3) and calculated particle mass concentrations (PMC; μg/m3) outside and inside of three buildings in Fairbanks, Alaska, during this summer wildfire event. For comparison, the measurements were repeated during a no-wildfire period in summer 2017. Our results show that the fire episode increased the total PNC by factors of 189.4–244 in the outdoor air and by 19.5–150 in the indoor air compared to the total PNC measured during a non-fire season. The PNC was primarily dominated by particles in the size range 0.3–1 μm (> 99%) at all locations during the fire season, whereas the PMC was dominated by particles in the size range from 2.5 to 10 μm (40–67%). The indoor to outdoor ratio (I/O) of PNC during the fire season was significantly lower for an unventilated building (I/O = 0.13 ± 0.001) as compared to those with active (filtered) ventilation (I/O = 0.76 ± 0.11 and 0.62 ± 0.02), suggesting that lower efficiency filters (

Owing to the vulnerability of Invar to moisture in the membranes of LNG tanker cargo tank construction platforms (CTCPs), an energy-efficient ventilation system is needed to maintain a suitable thermal-moisture environment and a healthy workplace. However, the optimal distribution of supply and return devices that would guarantee worker satisfaction, air quality, and energy efficiency is unclear. Therefore, we conducted numerical simulations to determine the worker satisfaction indices (temperature, relative humidity, and carbon monoxide concentration satisfactions), air quality index (contaminant-removal efficiency), and energy efficiency index (heat-removal efficiency) with supply vane angles ranging from -75° to 0° and two return vent positions (the bottom return vent and the top return vent). The analytic hierarchy process (AHP) entropy weight method was employed to determine the optimal supply vane angle and return vent position for three design targets by considering these indices simultaneously. The results indicated that, with a supply angle of -45° and a bottom return vent, worker satisfaction and air quality were prioritized. Furthermore, a high energy performance of the ventilation system was achieved with a -15° supply angle and a bottom return vent. Moreover, a comprehensive graph of supply vane angles at both return heights, which could provide a reference for optimizing the ventilation system in LNG-CTCPs, is described.

Deposition based direct radon and thoron progeny sensors give a more accurate estimate of the inhalation dose due to radon and thoron. The dependence of equilibrium factor on aerosol concentration and the ventilation rates has been studied. Deposited flux represents a better index of inhalation dose. Deposition based sensors are based on deposition velocity of the progeny atoms in the environment which show variability only in extremities like very low aerosol environment or very high ventilation rates, which has been presented in this work. Wire-mesh capped deposition sensor which is based on attached fraction deposition velocity, has been studied at different particle concentrations and it can be used for such occupational environments.

This paper outlines a unique case of the development of strategies to reduce ventilation and heating costs in Konsuln iron ore mine in northern Sweden. The mine, located just south of Luossavaara-Kiirunavaara Aktiebolag’s Kiruna iron ore mine, was developed as a test mine 2018–2020 for the Sustainable Underground Mining (SUM) project. Besides functioning as a test mine, Konsuln also contributes ore production. The existing mine ventilation system was designed for the current production rate of 0.8 million tons per annum (Mtpa). There is a plan to increase this rate to between 1.8 and 3 Mtpa in the future, and this requires the primary fans to be upgraded. Therefore, a study was carried out to determine whether using ventilation on demand (VOD) could avoid this fan upgrade and reduce Konsuln’s ventilation and heating power costs in the future. The study also investigated whether using battery electric vehicles (BEVs) along with VOD or as a standalone strategy could further reduce these power costs. In addition, the study analyzed the suitability of heating power reduction strategies presently or previously used in the Nordic countries and Canada to investigate potential additional strategies to reduce the heating power cost, the largest portion of Konsuln’s ventilation and heating power costs. The study found using VOD can avoid the expensive upgrading of the existing primary fans and reduce Konsuln’s ventilation and heating power costs in the future. Using BEVs can further reduce these costs. Finally, none of the Nordic and Canadian heating power reduction strategies is suitable for Konsuln because they require unique conditions that do not exist in Konsuln. Validerad;2022;Nivå 2;2022-03-15 (hanlid);For correction, see: Gyamfi, S., Halim, A. & Martikainen, A. Correction to: Development of Strategies to Reduce Ventilation and Heating Costs in a Swedish Sublevel Caving Mine—a Unique Case of LKAB’s Konsuln Mine. Mining, Metallurgy & Exploration 39, 239 (2022). https://doi.org/10.1007/s42461-021-00538-0

Increasing air movement by utilizing electric fans is among the common approaches for comfort and energy savings in buildings in summer; however, the use of electric fans is usually the forced constant airflow. This study reformed the one-chip computer program of a floor fan motor and simulated dynamic airflow through controlling the rotating frequency only. The flow field characteristics of constant, oscillated, sinusoidal airflows with periods of 10 s, 30 s, 60 s, 100 s were measured. The comfort performance was evaluated by chamber experiments, with 20 subjects exposed to six airflow patterns under 30 $dgC, 70%RH. The results showed that the simulated sinusoidal airflows had relatively higher turbulence intensity (32%–37%) and β values (> 0.4). While subjects’ thermal sensations were not statistically significant among six airflows, their reported discomfort symptoms during 60 min exposure were reduced under sinusoidal airflows. The calculated convective heat transfer shared similar variations to instantaneous air velocity and skin temperature. A large fluctuation of 10–50 W/m2 and higher total convective heat loss (3000–3500 W/m2) were found for sinusoidal period 30 s. This study develops a new method to simulate varying air velocities through conveniently controlling the fan motor amplitude and frequency, and verifies the comfortable feelings to dynamic sinusoidal airflows. The work benefits to improve the performance of the current electric fans with lower costs and promote the applications of personal ventilation devices in buildings, thus optimizing human thermal comfort, reducing dependences on air conditionings and achieving building energy efficiency.

The recent rapid development of underground utility tunnels (UUT) in China reflects the government’s resolve to improve the municipal service amid rapid urbanization. Although safety is of primary concern in the design and operation of the UUT, the moisture issue appears to be neglected. In the southern and eastern China, however, condensation in the UUT is noted and is believed to be responsible for the high rate of equipment failure and the deterioration of air quality inside the tunnel. To understand the moisture issue and its implications to the design and construction of the UUT, this study investigates the moisture balance in a section of the UUT in Suzhou city, eastern China. An experimental dehumidification study was carried out in a 200 m long 4.05 m × 2.5 m cable compartment with the objective to identify major sources and their strengths. Two refrigeration dehumidifiers were used to control the relative humidity. The results show that the most significant moisture source was the outdoor air through ventilation (values dependent on the air change rates), followed by the open water evaporation (~ 4.195 kg/hr) inside the tunnel and the leakage from the neighboring unconditioned compartments. The concrete walls had a strong buffering effect, which was a strong source at the beginning of the dehumidification (~ 17.171 kg/hr). A mathematical model was developed that can predict the tunnel humidity fairly well. The results suggested that the dehumidification needs to be included in the design, construction, and operation of the future utility tunnel. This includes reserved spaces for moisture control systems, an operation strategy for dehumidification, covered drainage system, and quality construction and maintenance.

Some Swedish school buildings built in the 1960s and 1970s experience indoor air quality problems, where the contaminants are suspected to come from the crawl space underneath the building. The poor indoor air quality causes discomfort among pupils and teachers. Installing an exhaust fan to maintain a negative pressure difference in the crawl space relative to indoors or increasing the ventilation in the classroom are two examples of common measures taken to improve the indoor air quality. However, these measures are not always effective, and sometimes the school building has to be demolished. The relation between pressure distribution, contaminant concentration in the classroom, outdoor temperature, wind, mechanical ventilation, and air leakage distribution is complex. A better understanding of these relations is crucial for making decisions on the most efficient measure to improve the indoor air quality. In this paper, a model for contaminant infiltration from the crawl space is used together with the Monte Carlo method to study these relations. Simulations are performed for several cases where different building shapes, building orientations, shielding conditions, and geographical locations are simulated. Results show, for example, that for a building with an imbalanced ventilation system, air is leaking from the crawl space to the classroom for the majority of cases and that concentration levels in the classroom are usually the highest during mild and calm days.

Thermal comfort has become one of the most important factors to be considered for the working efficiency and health of occupants in an indoor space. In addition, it is considered in the design of heating, ventilation, and air-conditioning systems for the management of building energy. In this study, the key factors influencing thermal comfort are briefly discussed, such as air temperature, air velocity, radiant temperature, relative humidity, insulation of clothes, and metabolic rate. These factors act in a complex manner, affecting people and causing physical and psychological changes. Also, human physical changes have a significant impact on the human body, including skin temperature, heart rate variability, and electroencephalogram measurements, and are modified by the surrounding thermal environment. In this article, the factors influencing thermal comfort and biosignals of humans are discussed, and recent related studies are introduced.

A review of the current literature suggests that heating, ventilating, and air conditioning (HVAC) systems increase the risk of nosocomial infections if not properly maintained and frequently scrutinized via quality checks. Herein, we present a novel hot water treatment (HWT) to produce aluminum oxide (Al2O2) nanostructures on the surface of aluminum (Al) sheets which are used as ductwork for HVAC systems. These aluminum oxide nanostructures, because of morphological changes undergone during hot water treatment, have the unique ability to inhibit bacteria growth using both physical and chemical mechanisms of action, i.e., contact cell membrane damage and reactive oxygen species (ROS). Air and surface analysis was done with an untreated ventilation system and the HWT ventilation system with Al2O2 nanostructures. We observed ~ 460 Escherichia coli colonies on agar plates in untreated control samples, while almost no bacteria growth was observed on the agar plates placed in the nanostructured aluminum sheets. This research clearly demonstrates the effectiveness of this novel, inexpensive, and chemical-free method of producing aluminum oxide nanostructures to decrease bacteria growth in HVAC systems and in turn significantly improving the air quality.

The relative location of inlets and outlets plays an important role in thermal comfort and energy conservation under ventilation modes for the building non-uniform indoor environment. Hence, a comparison study of thermal comfort and energy efficiency of eight widely-used ventilation modes for space heating was conducted in this study. Both subjective experiments and verified computational fluid dynamics (CFD) models were carried out. In the subjective experiments, the vote of local thermal sensation (LTS), overall thermal sensation (OTS) and draft sensation were collected. In the CFD simulations, RNG k-e model was applied to compare and analyze the air temperature field, turbulence intensity, ventilation effectiveness and air diffusion performance index (ADPI). The thermal comfort results showed that the air inlets are better located at the mid-height level of a wall, and the outlets are located at the same or higher height. While the results of the energy efficiency suggested that the inlets are better installed at the lower level of a wall, and the outlets should be placed far from the inlets. Since the results were conflict, the economic-comfort ratio was introduced to calculate and compare the thermal comfort and energy efficiency simultaneously. The final results concluded that it can achieve excellent thermal comfort performance without sacrificing energy efficiency when the inlets are at the height of 1.2 m of the front wall, and the outlets are at 1.2 m height of the back wall. Hence it is the best choice for the winter air distribution in northern China. This study can offer a guideline for the air terminal arrangements in non-uniform ventilation under heating mode.

The relationship between body mass and the respiratory microenvironment of burrowing animals is examined using artificial burrows containing surrogate animals that simulate O2 consumption by removal of air and simultaneous replacement with N2. Allometric relationships between body mass and burrow radius, nest chamber radius, and O2 consumption rate show that published mathematical predictions of diffusion-mediated gas exchange are adequate to describe the respiratory environments of animals in small blind-ending burrows through porous substrata. Diffusion is sufficient to ventilate burrows containing small mammals weighing less than 340 g, or subterranean nest chambers connected to the surface by one or more tunnels containing mammals weighing less than 30 kg. Outside of these limits, convection prevails and prevents the development of hypoxic conditions, particularly in burrows of mammals weighing more than 1300 g.

In recent years, air ventilation garments (AVG) have been reported effective to improve thermal comfort. In this study, an AVG incorporated with small fans was investigated on torso thermal comfort in moderate environment (Ta=25 °C, RH=50 %). Eight female subjects walked on the treadmill at a speed of 4 km·h−1 for 30 min and then rested for another 30 min. During the whole test protocol, the AVG was worn in three conditions of flow rates to examine which flow rate was the best choice to keep thermal comfort: fans off with no air ventilation (a controlled condition, CON), low flow rate (12 l/s, LOW) and high flow rate (20 l/s, HIGH). Results showed that HIGH made significantly lowered local skin temperature of the abdomen, scapula and the lower back (p

Focusing on the effect of street morphology on the ventilation efficiency, this paper presents 3D computational fluid dynamics (CFD) simulations of airflow and pollutant dispersion within urban-like three-way intersections, four-way intersections and roundabouts. The steady-state Reynolds-averaged Navier-Stokes (RANS) k-ε turbulence model is adopted and eight directions of the approaching wind are considered. The ventilation efficiency is evaluated using the ventilation indices purging flow rate (PFR) and the net escape velocity (NEV). Results show the sensitivity of the ventilation efficiency to the type of intersection, to the wind direction and to the number of branches. Specifically, the ventilation efficiency of the investigated three-way intersections is found to be better than that of the other intersections, especially when the angle between the streets is large, while that of roundabouts is also considerable, even with a similar average wind velocity, among the cases evaluated in this paper. Further, the influence of the wind direction for the three-way and four-way intersections is greater than that on roundabouts. Studies on the ventilation efficiency at urban intersections are not common in the literature and this work may help urban planners to better design such hub nodes of urban traffic, where traffic-related pollutants are not easily dispersed, thus avoiding harm to the health of pedestrians and surrounding residents.

Background Functional planning based merely on 4DCT ventilation imaging has limitations. In this study, we proposed a radiotherapy planning strategy based on 4DCT ventilation imaging and CT density characteristics. Materials and methods For 20 stage III non-small-cell lung cancer (NSCLC) patients, clinical plans and lung-avoidance plans were generated. Through deformable image registration (DIR) and quantitative image analysis, a 4DCT ventilation map was calculated. High-, medium-, and low-ventilation regions of the lung were defined based on the ventilation value. In addition, the total lung was also divided into high-, medium-, and low-density areas according to the HU threshold. The lung-avoidance plan aimed to reduce the dose to functional and high-density lungs while meeting standard target and critical structure constraints. Standard and dose–function metrics were compared between the clinical and lung-avoidance plans. Results Lung avoidance plans led to significant reductions in high-function and high-density lung doses, without significantly increasing other organ at risk (OAR) doses, but at the expense of a significantly degraded homogeneity index (HI) and conformity index (CI; p p > 0.05). Compared with the clinical plan, the mean lung dose (MLD) in the high-function and high-density areas was reduced by 0.59 Gy and 0.57 Gy, respectively. Conclusion A lung-avoidance plan based on 4DCT ventilation imaging and CT density characteristics is feasible and implementable, with potential clinical benefits. Clinical trials will be crucial to show the clinical relevance of this lung-avoidance planning strategy.

The critical velocity is the minimum velocity blowing towards the fire seat in tunnels to reduce the length of back-layering to zero, and it has been extensively adopted in the design of longitudinal smoke control in tunnels. A new concept, i.e., sub-critical velocity, is proposed in lieu of critical velocity for longitudinally ventilated tunnels. The sub-critical velocity allows the presence of back-layering upstream of the fire, provided that the back-layering is kept above the heads of motorists, thus posing no detrimental impact on them during evacuation. Experiments with propane fires with heat release rates of 3.7–25.5 kW were conducted in a 1/20 reduced-scale model tunnel. Both the lengths and the heights of back-layering at varying HRRs and longitudinal velocities were studied. Subsequently, the relationship of critical velocity and sub-critical velocity were developed. The results showed that sub-critical velocity is around 45–60% of the critical velocity. The adoption of sub-critical velocity in the design of longitudinally ventilated tunnels not only significantly reduces the cost of fans to drive the airflow, but also minimizes the impact of ventilation on heat release rates.

In the indoor environment of dental clinics, dental personnel and patients are exposed to a risk of infection because of the transmission of SARS-CoV-2 via particles or droplets. This study investigated the presence of SARS-CoV-2 RNA in indoor air of dental clinics in Tehran, Iran. Air sampling was done (n = 36) collecting particulate samples on PTFE filters at flow rates of 30 to 58 L/min. The samples were analyzed with novel coronavirus nucleic acid diagnostic real-time PCR kits. Only 13 out of 36 samples were positive for SARS-CoV-2 RNA. Logistic regression showed that sampling site’s volume, PM2.5 concentration, number of people, and number of active patient treatment units were significantly positively related with the presence of SARS-CoV-2 RNA. Thus, strategies to control the spread of COVID-19 should include reducing the number of infected people in dental clinics, adding filtration systems, and/or improving ventilation conditions.

The stability of longwall coal mines has been a challenging concern for geotechnical and mining engineers. Rock-bolting is the commonly used support system preventing roof and wall convergence and floor heave. This study attempts to suggest an optimized new rock-bolting pattern to effectively prevent the convergence of transportation and ventilation tunnels in Tabas coal longwall mine at panels 2 and 3. Three-dimensional numerical analysis was performed on the support system using FLAC3d code. Investigating the rock bolts axial force applied to the ventilation tunnels roofs shows that, the safety factor of the new support system compared to the old one can be reduced by the ratio of 1.2 to 2, while the amount of the roof displacements are still within the allowable limit. Moreover, rock bolts installed in the transportation tunnels walls have yielded about 10 m from the working face, which became stable in the redesigned rock-bolting pattern. In order to decrease the floor heave, a support system with inclined bolts was proposed, in which the amount of floor heave in the transportation and ventilation tunnels decreased about 40% and 33%, respectively.

The spaces must be designed in accordance with certain design principles for people to feel comfortable. In accordance with that, building ventilation is particularly important during hot periods to ensure thermal comfort. In this study, the effect of ventilation realized using a wind tower on the thermal quality of a classroom was investigated. In the study, two popular models (unidirectional and multidirectional wind tower) were studied, and the model that provided more ergonomic ventilation to sitting users based on climate conditions of the province of Trabzon (Turkey) during the month of August was determined. The more efficient model was studied further. Some dimensional changes in width, height, and shelf height were applied to it to find a model that provided more comfort for the used thermal conditions. The models were modelled and simulated using ANSYS FLUENT. Velocity distributions were generated to ease the interpretation of the results. With the calculated average wind speeds in different regions in the classroom, the thermal sensation in the space was evaluated. Furthermore, the thermal perception of users of the retained model was evaluated by entering thermal comfort parameter values calculated for the relevant region into the CBE thermal comfort tool available online. The change in the dimensional features of the wind tower had an impact on wind tower performance. Ventilation provided by wind towers under the thermal conditions of Trabzon in August often caused thermal discomfort.

Fire events in nuclear power plants represent a significant potential hazard and are an important contributor to the overall operational risks of these facilities. Consequently, a detailed understanding of fire and smoke propagation behaviour in such applications is required for fire performance-based engineering and risk assessment. This paper presents computational fluid dynamics modelling of a postulated fire scenario and occupant evacuation in a typical multi compartment nuclear building. The NIST Fire Dynamic Simulator (FDS) was used to model fire and smoke propagation by adopting large eddy simulation turbulence modelling approach. FDS simulation benchmarking was first performed against available experimental data of a two-storey compartment. Following this, a study was conducted to understand the smoke propagation, distribution of temperature, toxic gas concentrations, and smoke optical density inside a typical multi-compartment nuclear building. The effect of ventilation on the fire and smoke spread was also investigated. Human evacuation modelling was conducted to determine the required evacuation time and toxic gas dose for each occupant. The FDS predicted smoke parameters, including smoke optical density and toxic gas concentrations, were used as inputs to the evacuation modelling. The results suggest that ventilation flows decrease the smoke optical density due to smoke dilution and thereby result in a shorter time for the occupants to evacuate.

Background The aim of this study was to investigate the effect of feedback devices on visual attention and the quality of pediatric resuscitation. Methods This was a randomized cross-over simulation study at the Medical University of Vienna. Participants were students and neonatal providers performing four resuscitation scenarios with the support of feedback devices randomized. The primary outcome was the quality of resuscitation. Secondary outcomes were total dwell time (=total duration of visit time) on areas of interest and the workload of participants. Results Forty participants were analyzed. Overall, chest compression (P P = 0.002) when using a feedback device. Dwell time on the feedback device was 40.1% in the ventilation feedback condition and 48.7% in the chest compression feedback condition. In both conditions, participants significantly reduced attention from the infant’s chest and mask (72.9 vs. 32.6% and 21.9 vs. 12.7%). Participants’ subjective workload increased by 3.5% (P = 0.018) and 8% (P Conclusions The quality of pediatric resuscitation significantly improved when using real-time feedback. However, attention shifted from the manikin and other equipment to the feedback device and subjective workload increased, respectively. Impact Cardiopulmonary resuscitation with feedback devices results in a higher quality of resuscitation and has the potential to lead to a better outcome for patients. Feedback devices consume attention from resuscitation providers. Feedback devices were associated with a shift of visual attention to the feedback devices and an increased workload of participants. Increased workload for providers and benefits for resuscitation quality need to be balanced for the best effect.

The objective of this study is to investigate critical velocity and smoke maximum temperature beneath the ceiling in the connected area of branch tunnel with varying fire locations. The fire sources were located in the divergent connected area of the branch tunnel, to imitate traffic accidents near the branch point. A 1/20 scale model branch tunnel was built including main line before branch, main line after branch, and ramp. Experimental tests and numerical simulations were performed to explore smoke movement characteristics with longitudinal ventilation. The results showed that the enlarged cross-sectional area in branch tunnel caused the shortening of the back-layering length, and a modified model of back-layering length was proposed. The higher tunnel height in this work affected the critical condition of large fire; it caused a larger transition point of dimensionless critical velocity. A revised model was proposed for the maximum temperature rise of tunnel fires in the connected area of branch tunnel. The critical velocity kept unchanged when the branch angle increased from 0° to 20° because there is little change in the longitudinal smoke temperature. As the local tunnel width of fire source was increased, the required critical velocity was increased while the local effective velocity kept nearly the same.

To investigate how variations in positioning of laryngoscope and location of jet cannula on the laryngoscope body influence tracheal airflow during simulated high-pressure source supraglottic (HPSV) jet ventilation laryngoscopy using an anatomical model. A Broncho Boy Bronchoscopy model was modified to allow recording of tracheal airflow. A laryngoscope was suspended and positioned to simulate laryngoscopy. HPSV was delivered by a jet cannula attached to the body of the laryngoscope. Different combinations of laryngoscope angulation and cannula attachment were used and air flow recorded for each combination. Statistical analysis assessed the variations in flow. Significant statistical differences in flow effect (P 1 L/s) compared to downward or either side (

In this work, a passive detection technique is utilized to analyze radon, 222Rn, concentration levels in indoor and outdoor air after implanting 126 (CR-39) detectors for 130 days during the winter season in Irbid governorate, the second largest governorate in Jordan. Also, the spatial variations of the outdoor 222Rn concentrations in the air were interpolated and mapped using ArcGIS. Kriging method has been found the finest, among other geostatistical methods, for generating outdoor 222Rn concentration spatial interpolations with the least uncertainty and highest smoothness. The outdoor radon concentrations have ranged from 9 to 72 Bq m-3, while the indoors' have started as low as 17 and up to 102 Bq m-3. There was no clear realizable correlation among the identified indoor and outdoor air radon concentration levels. However, the calculated health risk indicators associated with radon inhalation show that around 11 residents in every 1000 could have an increased risk of lung cancer developing due to relatively higher radon gas exposure levels. These findings are important when applying radon policies both at the local and at the national levels, in terms of changing the air ventilation practices and for identifying areas of priority for further study, zoning, and land-use decision.

The thermal buoyancy generated by the difference in air density in a building can drive hot-pressed natural ventilation, which is an energy-efficient means of ventilation used to obtain higher air quality. Therefore, the effect of a single-point heat source with limited sides at different heights on stratified flow was studied in a naturally ventilated room in this paper. Based on the classical plume diffusion law of an independent point heat source and the mirroring principle, a calculation model of the thermal stratification height with a restricted source elevated to different levels was derived and validated. The quantitative effects of the heat source height from the floor, the effective opening area and other factors on the natural ventilation of hot pressure were analyzed. A threshold xT for the separation between a point source and a sidewall was defined to estimate whether the thermal plume was independent or restricted by a sidewall. And a method for calculating the threshold xT was obtained. This research can provide a reference basis for designing natural ventilation for buildings with a restricted heat source at different levels to achieve a desired indoor environment.

It is critical to comprehend the safety aspects of hydrogen fuel cell vehicles (FCVs) in semi-confined and confined environments. The hydrogen jet fire is a key hazard resulting from coincidental hydrogen release from onboard storage followed by ignition. The rise in temperature and depletion of oxygen inside the tunnel may cause calamitous debacles. In this study, comprehensive computational fluid dynamics (CFD) simulations were designed to understand the interactions of multiple hydrogen fires in a confined environment. CFD simulations for hydrogen and liquefied petroleum gas (LPG) jet fires were conducted inside a reduced scale model tunnel. The model is initially validated against the experimental data for a single LPG fire scenario. A parametric study was then made to understand the impact of the fire location in the tunnel and the ventilation velocity. The results show an increasing-decreasing trend in the temperature over the two fire sources before the temperature reaches a quasi-steady state for the cases without ventilation speed. However, in the presence of ventilation velocity, the temperature rises are seen until a quasi-steady-state is reached. The vicinity of the two flames in the tunnel influences ignition proficiency, dependent on the heat feedback enhancement and air supply restriction instruments. A temperature drop was seen at the ceiling as we move along the passage length. The ventilation velocity influences the proportion of fuel and oxygen, driving the burning proficiency to either increase or decrease. The overall ceiling temperatures were seen to reduce in the presence of higher ventilation velocity. In conclusion, for hydrogen and LPG fire interaction, a distinction in the ceiling temperature pattern was seen between the two because of the disparity in the emissivity of the two fuels.

Thermal comfort of occupants in conventional vehicles driven by an internal combustion engine is controlled by heating, ventilation, and air conditioning (HVAC) system. However, the operation of a conventional HVAC system decreases the mileage of electric vehicle (EV) in the heating mode by nearly 50 %. Thus, local radiant heating was proposed as a heating strategy to reduce electric energy consumption while providing reasonable thermal comfort. In this work, we developed a personalized overall thermal sensation (OS) model using machine learning to evaluate the thermopsychological effect of local radiant heating and simulate the OS of occupants in EVs. Data were obtained from a real EV that went through a cold environmental chamber and were evaluated using random forest algorithm. By considering individual thermal preferences of occupants, we predicted the OS for each subject with higher accuracy by a factor of 2.6 compared with the prediction performed using the weighted average method. Total energy consumption was reduced by approximately 10 % in the EV equipped with local infrared radiant warmers while providing OS that was comparable with that of the HVAC system.

Construction ventilation runs through the entire construction process of large underground caverns and is the key to ensuring construction progress and project safety. For the specific underground cavern group of pumped-storage power plants, a three-dimensional model is constructed, and the CFD method based on fluid mechanics theory is used to simulate the ventilation flow field of the underground cavern group. Through the comparison of the airflow in the main caverns and the air velocity distribution law, Quantitative analysis of the influence of the diameter of the ventilation shaft and the inclination of the shaft on the ventilation flow field shows that when the diameter of the ventilation shaft is 8 m and the inclination of the shaft is 80°, the ventilation effect in the underground cavern group is the best. Applying this scheme to engineering practice and conducting on-site tests, the average relative error of the measuring points is 11.32% by comparing the measured data and the simulation results, which verifies the correctness of the CFD method used. It provides reference value for studying the construction ventilation of underground caverns.

Smoking indoors generally exists in daily life, and highlighting the importance of reducing the hazard from smoke particles to non-smoking occupants is crucial. To quantitatively investigate the flow characteristics in a ventilated room, a computational fluid dynamics (CFD) method is used to assess the velocity, concentration, and inhalation levels of indoor particles using a manikin with a realistic upper respiratory tract. It realizes smoke particles’ diffusion simulation from room scale to human upper respiratory tract scale. An experiment is also performed to measure PM2.5 concentrations. With the increase of a high air change rate per hour (ACH) from zero to 12.32 and 17.14, the indoor particle concentration reduces by 58.5% and 67.9%, the number of inhaled particles decreases by 22.9% and 43.8%, and the particle concentration around the occupant decreases by 10.3% and 17.5%, respectively. It shows that indoor ventilation has a drastic effect on flow characteristics, particle concentrations, and particle outcomes. ACH of 17.14 is found to significantly reduce the particle concentration around the occupant and decrease the number of smoke particles inhaled and remaining indoors. It indicates that the ventilation equipment can reduce the number of smoke particles in the room. There are still 41.3% and 31.9% particles remaining in the room when the ACH is 12.32 and 17.14, which does harm to human health.

The transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) occurs via contact with contaminated surfaces and inhalation of large airborne droplets and aerosols. As growing evidence of airborne SARS-CoV-2 transmission has been reported worldwide, ventilation is an effective method of reducing the infection probability of SARS-CoV-2. This leads to such questions as “What is a sufficient ventilation rate for avoiding the risk of COVID-19 infection?” Therefore, this study evaluates the critical ventilation rates according to room size and exposure time when a susceptible person is in the same room as an infector. The analytical results were based on data obtained from 70 confirmed COVID-19 cases transmitted in confined spaces without an operational ventilation system. The results reveal that even with active ventilation (20 h−1 air exchange rate), the critical exposure time for a susceptible person with a COVID-19 infector in a small space of 20 m3 is less than 1 h. For other cases (different space sizes), the estimated air exchange rates for avoiding the risk of infection are generally higher than various requirements for good indoor air quality. The findings of this study will provide guidelines for determining sufficient ventilation rates to protect against the highly contagious COVID-19.

The present study revealed that the traditional cooking practices could load ~ 2.8 ± 1.2 mg/m3 of PM2.5 in the kitchen, leading to womenfolk at risk. The high variability was observed in the measured values as the concentrations were influenced by several factors such as species of fuel wood used, amount of fuel burnt, duration of cooking, ventilation facility in the kitchen, etc. The calculated health quotient showed that the long-term prolong exposure to such PM2.5 concentrations can reduce the lung capacity of the exposed persons due to harmful impacts. A survey about air pollution awareness was also conducted among the village inhabitants, and findings of pollution loading in the kitchen were also shared with them for enabling them to make more informed decisions about choice of fuel types and precautions during the cooking process for avoiding the health risk.

Elbow resistance is an important part of energy consumption in ventilation and air conditioning (VAC) systems. By considering the structural characteristics of bat wings and humpback whale pectoral fins, a simplified leading edge for sawtooth guide vanes is designed. Based on the theory of fluid mechanics, the resistance reduction mechanism of the sawtooth guide vane is analyzed. The numerical calculation results show that proper sawtooth groove parameters for the guide vane can effectively reduce the elbow resistance. Compared with that for a normal guide vane, the maximum resistance can be reduced by approximately 9% with the new design. In addition, we analyze the influence of the sawtooth guide vane on the entropy production of the duct elbow and the relationship between entropy production and the resistance of the duct elbow. Finally, the resistance reduction performance of the sawtooth guide vane is verified through full-scale tests.

Indoor particulate matter (PM) concentrations may be high due to indoor PM generation as well as PM introduced from the outdoors in residential buildings. In particular, as building airtight performance has been strengthened to reduce energy consumption, the indoor-generated PM has greatly influenced a person’s overall PM exposure. The indoor activities of residents may generate and resuspend PM, which in turn increases the indoor PM concentration. This study aims to analyze the characteristics of indoor PM generation by activities in a residential building and the removal effect of the ventilation methods. Field measurements were accomplished for indoor PM generation activities in real conditions, such as vacuum cleaning, cooking (fish and pork), air freshener spraying, and scented candle burning in a residential building. As a result, the PM concentration was the highest for broiling fish, with a concentration of 15.714 mg/m3 for PM10 and 13.679 mg/m3 for PM2.5. The decreasing order of the peak concentration for indoor activities was cooking, burning scented candles, vacuuming, and spraying air freshener. Additionally, the residual PM concentration exceeded the standard upper limit even 30 min after most of the PM generation activities ended. Especially, in the cooking activity, with the highest PM generation, PM could not be removed properly even when the range hood was operated. This is because the static pressure loss of the range hood in an air-tightened house and additional air supply or window opening can improve the PM removal performance of the range hood.

In the daytime, building facades and ground surfaces are heated by solar radiation, and the resulting buoyancy can change the flow field inside street canyons. In this study, the impacts of uneven and time-varying heating of surfaces inside an ideal urban street canyon (aspect ratio = 1) on single-sided indoor natural ventilation are analyzed. This work introduces a methodology for a numerical approach based on the coupling between a computational fluid dynamics (CFD) model and an energy balance model. First, EnergyPlus is employed to calculate the time-varying and uneven surface heating. Simulations are performed at four typical study times (05:00, 09:00, 15:00, 20:00) during a hot summer day (July 15) in Wuhan, China. Second, the surface temperature results are transferred to OpenFOAM for CFD simulation. Two inlet wind velocities (Uref) are investigated. The results show that for a relatively strong ambient wind (Uref = 3 m/s), the buoyancy caused by surface heating does not significantly change the airflow structures and indoor ventilation compared with those in the isothermal case. However, for a weak ambient wind (Uref = 0.5 m/s), the airflow structures inside the street canyon vary with the time of day. Moreover, the average air exchange rate (ACH) differs by −25.0% to 15.9% compared with that in the isothermal case, and the ACH of a single room increases by up to 2710%. The results indicate that the surface-heating-induced buoyancy is nonnegligible and should be carefully investigated, especially for weak ambient winds.

Tall buildings in cold climates have unique challenges in maintaining indoor air quality due to stack effect. During the heating season, interior air buoyancy creates large pressure differentials in vertical shafts that can drive airflow from lower floors into upper floors. This pressure differential can result in the spread of contaminants throughout a building. Most recently, concern over COVID-19 has increased attention to the potential spread of airborne diseases in densely populated buildings. For many multi-unit residential buildings, suite ventilation has traditionally relied upon fresh air supplied through a mechanically pressurized corridor. In cold climates, large pressure differentials created by stack-effect can reduce the effectiveness of this approach. Multizone and CFD simulations are employed to analyze airflow and contaminant spread due to stack effect. Simulations are conducted on an idealized model of a 10-storey building using a range of experimentally derived airtightness parameters. Simulations demonstrate stack effect can reduce corridor ventilation to suites and even reverse the airflow for leakier buildings. Reduced airflow to suites can result in the accumulation of contaminants. Reversal of the airflow can allow contaminants from a suite to spread throughout the building. Contaminant spread is illustrated as a function of mechanical ventilation, building airtightness, and ambient temperatures. Strategies to reduce the influence of stack effect on mechanically pressurized corridors are discussed.

In order to control the dust pollution produced by air leg rock drill in the trolley area during the excavation of long-distance single ended tunnel, the full-scale physical model of working face was established by using FLUENT software, and the numerical simulation analysis of tunnel drilling ventilation and dust removal parameters was carried out. The results show that it is difficult to control the dust pollution of the face by conventional ventilation, and the drilling dust is distributed in the range of 10 m from the face; after the introduction of the long pressure and short suction ventilation scheme, when the ratio of compressed air volume to exhaust air volume is 0.72, the height of the pressure fan is 2.5 m, the distance between the pressure fan and the palm face is 20 m, and the exhaust fan is 12 m away from the palm, the dust concentration control efficiency of the working face is increased by about 60%. Therefore, in the similar long-distance single head tunnel construction, it is appropriate to adopt the dust removal method of long-distance short suction and exhaust fan to ensure the working environment.

During the circulation of air in the garment’s microclimate, the body extra heat dissipates to the environment. This event is an important factor in thermal comfort and ventilation. In this study, a heating cylinder was designed and calibrated to assess the ventilation occurrences in garment as a simulator of the human body. Tubular samples with different sizes were prepared using double jersey weft knitted fabric in order to obtain five levels of air gap thickness, including −1.5, 0, 1, 1.5 and 2 cm. Experiments were carried out in two conditions including without wind and by wind blowing with eight different wind speeds include 0.5, 1, 1.5, 2, 2.5, 3, 5 and 7 m/s. In each condition, the air gap’s temperature was considered as the main parameter for examination of the microclimate ventilation. The obtained outcomes revealed that by increasing the air gap thickness to more than 1 centimetre, the ventilation rate increased significantly. In the absence of wind, the change in the air gap’s temperature was not considerable for all sizes due to the natural convection phenomena that were slow. An increase of wind speed to more than 1 m/s led to a rise in the forced convection heat loss and took less time for the system to reach the equilibrium temperature; hence, higher ventilation rate was achieved. Moreover, by the increment of wind speed, the reduction of microclimate temperature follows a power function and at higher wind speeds remained approximately constant. According to the statistical analysis of results, it was confirmed that the ventilation rate of garment was influenced by wind speed; however, the influence of air gap thickness only in the absence of wind is significant.

The hypoxic environment at high altitudes causes various sleep disorders. Diffuse oxygen enrichment is an effective way to alleviate sleep disorders and improve the built environment in high altitude areas. In this study, a novel point source local diffuse oxygen supply method was proposed to improve the sleeping oxygen environment. The oxygen supply performance was investigated by the computational fluid dynamics (CFD) method including the oxygen concentration and air velocity distributions. A sleeping experiment was conducted on the plateau to validate the CFD model. The occupied zone including the inhalation zone and the active zone was defined. The results showed that the oxygen concentration showed a rapid rise, then decreased slowly, and finally tended to be stable. The oxygen concentration after stabilization was remarkably influenced by indoor ventilation rate. The sleeping environment’s improvement was examined considering the oxygen enrichment efficiency, uniformity, stability and human comfort demand. The optimal strategies were recommended with a ventilation rate of 1 air change per hour, supplied oxygen concentration of 90%, and jet distance of 0.50 m. The study contributes to improving the oxygen environment and human sleep quality in an effective and energy-saving approach to the sustainable development of buildings in high altitude areas.

If a pulmonary pathology can be removed by anatomical segmentectomy, the need for lobectomy is obviated. The procedure is considered oncologically equivalent and saves healthy lung tissue. In every segmentectomy, lung parenchyma must be transected in the intersegmental plane. Using an ex vivo model based on porcine lung, three transection techniques (monopolar cutter + suture, stapler, and Nd:YAG laser) are to be compared with respect to their initial airtightness. At an inspiratory ventilation pressure of 25 mbar, all three preparations were airtight. Upon further increase in ventilation pressure up to 40 mbar, the laser group performed best in terms of airtightness. Since thanks to its use of a laser fibre, this technique is particularly suitable for minimally invasive surgery; it should be further evaluated clinically for this indication in the future.

Shock wave pressure, high temperature flames, and toxic gases are among the factors that cause mine ventilation system failure following a gas explosion. Herein, we propose a Support Vector Regression (SVR)-based machine learning model to quickly determine the propagation of these disaster-causing hazards throughout the whole ventilation network. FLACS was used to simulate the explosions in a straight roadway with different spatial geometric parameters and gas explosion equivalents. Four SVR machine learning models were constructed by incorporating the roadway’s cross-sectional area, length of gas filling, gas concentration, and the distance between the observation point and the explosion source as inputs, while the shock wave pressure, flame temperature, time to the maximum temperature, and pressure served as outputs. The proposed model can quickly and accurately predict the propagation of disaster-causing hazards for a given explosion position and equivalent. As such, it plays a significant role in determining the ventilation system failure mode and aids decision makers and rescuers in developing a rescue and refuge plan.

BackgroundThe novel coronavirus disease 2019 (COVID-19) undermines the benefits of cancer screening. To date, no study has identified specific infection control methods. We aimed to provide practical methods for COVID-19 risk reduction during breast cancer screening mammography (MMG) by examining an overview of potential contamination routes of aerosols and possible risks for patients and health care providers.MethodsComputational fluid dynamics (CFD) simulations were conducted for airflow and aerosol dispersion in a 3D virtual model of a mobile MMG laboratory room. This model was constructed based on the actual mobile screening MMG bus ‘Cosmos’ in the Chiba Foundation for Health Promotion & Disease Prevention. Examiner and patient geometries were obtained by scanning an actual human using a 3D Scanner. Contamination of the room was evaluated by counting the numbers of suspended and deposited aerosols.ResultsWe applied the CFD simulation model to the exhalation of small or large aerosols from a patient and examiner in the MMG laboratory. Only 14.5% and 54.5% of large and small aerosols, respectively, were discharged out of the room with two doors open. In contrast, the proportion of large and small aerosols discharged out of the room increased to 96.6% and 97.9%, respectively, with the addition of forced gentle wind by the blower fan. This simulation was verified by a mist aerosol experiment conducted in the mobile MMG laboratory.ConclusionAdding forced ventilation to a MMG laboratory with two doors open may enable risk reduction dramatically. This could be applied to other clinical situations.

Load forecasting can increase the efficiency of modern energy systems with built-in measuring systems by providing a more accurate peak power shaving performance and thus more reliable control. An analysis of an integrated CO2 heat pump and chiller system with a hot water storage system is presented in this paper. Drastic power fluctuations, which can be reduced with load forecasting, are found in historical operation records. A model that aims to forecast the ventilation system heating demand is thus established on the basis of a long short-term memory (LSTM) network. The model can successfully forecast the one-hour-ahead power using records of the past 48 h of the system operation data and the ambient temperature. The mean absolute percentage error (MAPE) of the forecast results of the LSTM-based model is 10.70%, which is respectively 2.2% and 7.25% better than the MAPEs of the forecast results of the support vector regression based and persistence method based models.

Risks shoot up when virus particles accumulate in buildings, but it’s not clear how best to improve ventilation. Risks shoot up when virus particles accumulate in buildings, but it’s not clear how best to improve ventilation.

This paper presents results of measurements of 99mTc activity concentration in air and nuclear medical personnel blood during ventilation–perfusion SPECT lung scans. 99mTc activity measurements were conducted at the Nuclear Medicine Department, John Paul II Hospital, Krakow. Technicians and nurses who perform examinations were equipped with personal aspirators enabling air sampling to determine the radiation exposure at their workplaces. Measurements allowed to evaluate the concentration of 99mTc in 14 air samples and it ranged from 7800 ± 600 to 10,000 ± 1000 Bq m−3 for air samples collected by technicians and from 390 ± 30 to 600 ± 40 Bq m−3 for air samples collected by nurses. In addition 99mTc concentrations in blood of medical personnel were determined in 24 samples. For technicians the maximum 99mTc blood concentration levels reached 920 ± 70 Bq L−1 and 1300 ± 100 Bq L−1. In the case of nurses, the maximum estimated activity concentrations were about ten times lower, namely 71 ± 7 Bq L−1 and 39 ± 3 Bq L−1. Although the intakes appear to be relatively high, the resulting annual effective doses are about 34 µSv for technicians and only 2 µSv for nurses.

Understanding the climatic conditions in underground mines is necessary for efficient ventilation design, cost savings, and to ensure the health and safety of mine workers. Large volumes of ventilation and climatic data including air volume, barometric pressure, dry bulb temperature, and relative humidity were collected at active underground precious metal mines in Nevada, which allows for the determination of wet bulb temperature and other key parameters. Through the utilization of neural networks, the wet bulb temperature at the bottom of the intake shafts is predicted, while taking into account the “thermal flywheel effect” (TFE). Wet bulb temperature is one of the most important climatic parameters to model and understand because it significantly affects the work conditions and the cooling capacity of the ventilating air. The accurate prediction of the dry bulb and the wet bulb temperatures at the bottom of intake shafts is critical when assessing the climatic conditions in future underground mines and deciding on whether a cooling system is needed to assure adequate working conditions throughout the mine. By utilizing accurate predictions of wet bulb temperatures and other climatic parameters, mine personnel will be safer as reported by Bluhm et al. (2003), and a more accurate ventilation design can be achieved resulting in major cost savings for underground mines.

Irregularity in plan shape is very common and sometimes unavoidable for providing proper ventilation in and around a tall building. In this present study, the pros and cons of using irregular type butterfly plan-shaped building over regular square plan-shaped buildings are discussed. Two turbulence models, standard k-epsilon (SKE) and shear stress transport (SST), were used for the validation of the numerical model, and the data were compared with previous experimental results of Commonwealth Advisory Aeronautical Research Council (CAARC) building model from literature. The force coefficients (both X and Y direction) and external pressure coefficients are observed considering four different heights and five different irregularity ratios of the butterfly building for wind incidence angle ranging between 00 and 450 at an interval of 150. The variation of pressure along various faces of the building is analysed with the help of contours and horizontal peripheral lines. With the increase in the irregularity ratio, the overall plan area consumed by the building is increased although the ventilation of the building is improved drastically along with a decrease in the force coefficient acting on the building and the maximum local suction at the corner regions.