Theoretical and experimental substantiation of the system of local removal of harmful substances during the combustion of candles in the worship hall of Orthodox churches and cathedrals

The Local Exhaust Ventilation (LEV) is the most common type of engineering control equipment used to control employees' exposure to chemicals that are hazardous to their health. Before a contaminant disperses into the workroom environment, LEV systems operate on the principle of capturing it at or near its source. The welding guideline stated that the suggested minimum hood velocity is 100 ft/min, the recommended velocity along ducts for vapors, gases, and smoke is 1000 ft/min, and 2000 ft/min. The research objective is to identify the effectiveness of the LEV system using validation computational fluid dynamics (CFD) simulation. The data collected by experimental design during the pre-testing phase of the LEV system is quantitative and obtained through a fieldwork survey and document analysis. Findings found that LEV systems are effective to be used and meet all the minimum requirements set by the guideline. In CFD simulation, upon validation, the average absolute error obtained from the case study is 8.4%. There is good agreement between actual experimental and CFD simulation results, and the acceptable validity of CFD simulation is less than 10%. Therefore, simple CFD modeling is a tool to simulate air velocity in the LEV system, saving labor costs and time consumption during the earliest stage of LEV design development before actual construction. This study's outcome can serve as a benchmark or guideline for training facilities equipped with the LEV system to prioritize safety and health.

The performance of a commercially available Local Exhaust Ventilation (LEV) system for controlling mist, vapor and fume exposures during two-piece slim retractable aluminium can production line was assessed. This study focused on monitoring of LEV system performance in different phases of production which are drawing and wall ironing. Data such as static pressure, velocity pressure, transport velocity and flow rate values was obtained as a specific requirement to analyze the performance of the system. The first LEV system used to control mist exposure from drawing activities and the second system was implemented to control fume and vapor during ironing wall process. The performance of the system was investigated and compared with standard as required by USECHH Regulation 2000. The results of LEV system monitoring were discussed and several recommendations were proposed to improve the performance of the system and to reduce the mist, fume and vapor exposure for occupational safety and health purposes.

Acute and chronic exposure to xylene can result in a range of negative health effects. However, xylene is widely used and emitted in the air of workplaces. To evaluate xylene vapor concentrations to guide the design and evaluation of a local exhaust ventilation (LEV) system to reduce exposure in a pesticide production factory. A real time volatile organic compound (VOC) monitor was used to determine the workers' time-weighted average (TWA) exposure. A LEV system was designed, and then, workers' exposure to xylene vapor was evaluated. We found that worker's exposure to xylene (4·7±5·5 ppm) was lower than the standards recommended by the American Conference of Governmental Industrial Hygienists (ACGIH) and the Occupational safety and health administration (OSHA). Despite the low TWA exposures, the short-term exposures for some workers were higher than STEL levels. Three canopy hoods were designed and installed with capture velocities of 0·508 m second(-1) and duct velocity of 10·16 m second(-1). We found that an exhaust ventilation system had a significantly reduced occupational exposure to xylene vapor.

Respirable crystalline silica dust exposure in residential roofers is a recognized hazard resulting from cutting concrete roofing tiles. Roofers cutting tiles using masonry saws can be exposed to high concentrations of respirable dust. Silica exposures remain a serious threat for nearly two million U.S. construction workers. Although it is well established that respiratory diseases associated with exposure to silica dust are preventable, they continue to occur and cause disability or death. The effectiveness of both a commercially available local exhaust ventilation (LEV) system and a water suppression system in reducing silica dust was evaluated separately. The LEV system exhausted 0.24, 0.13, or 0.12 m 3 /sec of dust laden air, while the water suppression system supplied 0.13, 0.06, 0.03, or 0.02 L/sec of water to the saw blade. Using a randomized block design, implemented under laboratory conditions, the aforementioned conditions were evaluated independently on two types of concrete roofing tiles (s-shape and flat) using the same saw and blade. Each engineering control (LEV or water suppression) was replicated eight times, or four times for each type of tile. Analysis of variance was performed by comparing the mean airborne respirable dust concentrations generated during each run and engineering control treatment. The use of water controls and ventilation controls compared with the “no control” treatment resulted in a statistically significant (p < 0.05) reduction of mean respirable dust concentrations generated per tile cut. The percent reduction for respirable dust concentrations was 99% for the water control and 91% for the LEV. Results suggest that water is an effective method for reducing crystalline silica exposures. However, water damage potential, surface discolorations, cleanup, slip hazards, and other requirements may make the use of water problematic in many situations. Concerns with implementing an LEV system to control silica dust exposures include sufficient capture velocity, additional weight of the saw with the LEV system, electricity connections, and cost of air handling unit.

A study was conducted to evaluate the effectiveness of a local exhaust ventilation system for a foundry casting-cleaning operation in which a worker cleaned gray iron castings using a variety of handheld chipping and grinding tools. The operation originally had an exhaust system consisting only of an exhaust duct terminating approximately 1 m (3 ft) above the floor and 2 m (6 ft) from the casting-cleaning workstation. An earlier evaluation of this original control system found time-weighted average exposures to respirable silica ranging from 124 to 160 micrograms/m3. The local exhaust ventilation system evaluated in this present study consisted of a downdraft booth outfitted with a turntable for manipulating the castings. The modified local exhaust ventilation system was installed at this facility and connected to the existing plant exhaust ventilation system through the original ductwork. A direct-reading instrument was used to measure the operator's respirable aerosol exposure concentrations during a single day both before and after the installation of the new workstation. The same worker was sampled both times. The operator's activities were recorded on videotape so that the exposures associated with the various tools could be determined. While day-to-day variability could not be accounted for, depending on the type of tool used the local exhaust ventilation system reduced exposures by 59 to 79% during casting cleaning by the sampled worker when compared with the original configuration. These reductions were statistically significant.

To control chemical hazard, engineering control is one of the Hierarchy of Controls that protects workers from chemical hazard. Engineering control is accomplished by removing hazardous conditions by placing a barrier between the worker and the hazard. Local ventilation system is widely used in laboratories to remove any chemical agents that are released from any chemical reactions. The importance of these ventilation systems is to prevent any health complications to persons in the laboratory due to chemical exposure. İn this paper, the effects and effectiveness of sash height to vapor source position to effectiveness of local exhaust ventilation (LEV) system were studied and identified using vapor flow from the stimulated carbon dioxide (CO2) and water vapor. Eight LEVs were inspected. The stimulated vapor as a tracer was produced by mixing dry ice into hot-boiled water (100oC). The dispersion stimulated CO2 and water vapor inside and outside the LEV system, and this can predict the efficiency of LEV systems based on visual inspection. The results revealed that each LEV showed a different time taken to draw out the vapor from the inside of the fume hood.

Drilling large holes (e.g., 10–20 mm diameter) into concrete for structural upgrades to buildings, highways, bridges, and airport runways can produce concentrations of respirable silica dust well above the ACGIH® Threshold Limit Value (TLV® = 0.025 mg/m3). The aim of this study was to evaluate a new method of local exhaust ventilation, hollow bit dust extraction, and compare it to a standard shroud local exhaust ventilation and to no local exhaust ventilation. A test bench system was used to drill 19 mm diameter x 100 mm depth holes every minute for one hour under three test conditions: no local exhaust ventilation, shroud local exhaust ventilation, and hollow bit local exhaust ventilation. There were two trials for each condition. Respirable dust sampling equipment was placed on a “sampling” mannequin fixed behind the drill and analysis followed ISO and NIOSH methods. Without local exhaust ventilation, mean respirable dust concentration was 3.32 (± 0.65) mg/m3 with a quartz concentration of 16.8% by weight and respirable quartz dust concentration was 0.55 (± 0.05) mg/m3; 22 times the ACGIH TLV. For both LEV conditions, respirable dust concentrations were below the limits of detection. Applying the 16.8% quartz value, respirable quartz concentrations for both local exhaust ventilation conditions were below 0.007 mg/m3. There was no difference in respirable quartz dust concentrations between the hollow bit and the shroud local exhaust ventilation systems; both were below the limits of detection and well below the ACGIH TLV. Contractors should consider using either local exhaust ventilation method for controlling respirable silica dust while drilling into concrete.

Over 766 million people have been infected by coronavirus disease 2019 (COVID-19) in the past 3 years, resulting in 7 million deaths. The virus is primarily transmitted through droplets or aerosols produced by coughing, sneezing, and talking. A full-scale isolation ward in Wuhan Pulmonary Hospital is modeled in this work, and water droplet diffusion is simulated using computational fluid dynamics (CFD). In an isolation ward, a local exhaust ventilation system is intended to avoid cross-infection. The existence of a local exhaust system increases turbulent movement, leading to a complete breakup of the droplet cluster and improved droplet dispersion inside the ward. When the outlet negative pressure is 4.5 Pa, the number of moving droplets in the ward decreases by approximately 30% compared to the original ward. The local exhaust system could minimize the number of droplets evaporated in the ward; however, the formation of aerosols cannot be avoided. Furthermore, 60.83%, 62.04%, 61.03%, 60.22%, 62.97%, and 61.52% of droplets produced through coughing reached patients in six different scenarios. However, the local exhaust ventilation system has no apparent influence on the control of surface contamination. In this study, several suggestions with regards to the optimization of ventilation in wards and scientific evidence are provided to ensure the air quality of hospital isolation wards.

Ventilation is used to control indoor air quality for maintaining the health and performance of human and ensuring healthy environment. It is known that the environmental criteria are dictated by temperature, humidity, and contamination. In a case study at XY company, questionnaires were distributed to the workers and interviews were conducted to find out the level of satisfaction on working conditions in certain areas. 70% respondents reported feeling uncomfortable because of heat, dust and hot environment. An analysis of indoor air quality was carried out to measure the temperature at pouring area. Based on the analysis, the range of temperatures is from 35°C to 43°C. A local exhaust ventilation (LEV) system was design for improve indoor air quality and reduce extreme heat. The LEV system was proposed for the pouring area to capture then discharged heat or contaminants through a series of strategically placed overhead ducts.

Introduction: One of the ways to control hazards with an engineering approach in an effort to reduce hazards due to chemical reactions in the laboratory is to install a ventilation system, especially in the Atomic Absorption Spectrophotometer (AAS). The research objectives of this study are to evaluate the implementation of the Local Exhaust Ventilation System in the AAS room. Method: This study used a descriptive observational method with a cross-sectional approach. It was carried out at the Testing Laboratory of the Technical Implementation Unit (henceforth-UPT) of Occupational Safety Surabaya. Data collection was carried out through direct observation in the field to determine the LEV system components and to measure the flow velocity in the inlet and outlet areas of the LEV system. The data obtained were analyzed descriptively by describing the situation systematically and factually. The data were then presented in the form of narration, tabulation, and figures. Results: The conditions of the Local Exhaust Ventilation (LEV), in terms of the design, type and material of each component such as the hood, ducting system and pump machine as well as the fan, are already in accordance with the tool specifications and ASHRAE standards. However, the LEV system has not installed an air cleaner. The results of the measurement show that flow velocity in the LEV system has met the standard, which is 10 m/s with the danger of fume contaminants. In fact, its volumetric flow rate has decreased by more than 20%. Conclusion: laboratory management is advised to consider installing an air cleaner on the LEV system installed in the Hitachi AAS so that contaminants released in the air are cleaner and more environmentally friendly.Keywords: hazard control, laboratory, local exhaust ventilation, ventilation

In response to increasing focus on occupational exposures to welding fume, a 10-year series of personal exposure measurements was analyzed for the two main welding processes (Shielded Metal Arc Welding or Stick and Tungsten Inert Gas welding or TIG) used in an oil refinery setting. Exposures from ancillary gouging and grinding were also analyzed. The operations were conducted under a permit-to-work system, which stipulated control measures in the form of ventilation and respiratory protective equipment (RPE) depending on the work environment, base metal, and welding process. The analysis focused on three health hazards of interest: total particulate (TP); hexavalent chromium (Cr (VI)); and manganese (Mn). The study’s aims were the analysis of exposure levels related to operational conditions to verify the adequacy of required control measures and the generation of quantitative information for the development of predictive exposure models. Arithmetic mean exposures were 2.01 mg/m3 for TP (n = 94), 13.86 µg/m3 for Cr (VI) (n = 160), and 0.024 mg/m3 for Mn (n = 95). Requirements and practices for ventilation and use of RPE appeared adequate for maintaining exposure levels below maximum use concentrations. Predictive models for mean exposure levels were developed using multiple linear regression. Different patterns emerged for TP, Cr (VI), and Mn exposure determinants. Enclosed or confined work environments were associated with elevated exposure levels, regardless of the provision of local exhaust or general dilution ventilation. Carbon arc, used with gouging and grinding, contributed significantly to TP exposure (p = 0.006). The relative TP source strengths of the two main welding processes were comparable to the literature data. For Cr (VI), stick welding was associated with approximately 50-fold (p < 0.001) higher exposure potential than TIG welding. For Mn, this difference was approximately 2.5-fold. Differences were observed across the three analytes in exposure reduction efficiency of local exhaust ventilation (LEV) compared to natural ventilation, possibly due to ineffective use in confined spaces. These findings contribute to the overall understanding of TP, Cr (VI), and Mn exposures from welding and required controls in an oil refinery setting.

Protection of healthcare workers during aerosol-generating procedures with local exhaust ventilation

Local exhaust ventilation systems for the gross anatomy laboratory

Energy saving and indoor thermal comfort evaluation using a novel local exhaust ventilation system for office rooms

In general, control of metal dust from hand-held disk grinders is difficult because such respirable dust tends to disperse in every direction around the grinding wheel and cannot be captured effectively by a conventional exhaust hood. The author described the application of a custom-made tool-mounted local exhaust ventilation (LEV) system attached to a hand-held disk grinder, and by laboratory experiments assessed its effectiveness at dust control. The effectiveness of the LEV for dust control was assessed by determining the respirable dust concentration around the grinding wheel during metal surface grinding with and without the use of the LEV. It was shown that the average respirable grinding dust concentration decreased from 7.73 mg/m(3) with the LEV off to 4.87 mg/m(3) with the LEV on, a mean dust generation reduction of about 37%.