IMPROVING INDOOR AIR QUALITY USING LOCAL EXHAUST VENTILATION (LEV)

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.

ABSTRACTIntroduction: The emergence of COVID-19 pandemic that occurred at the end of December 2019 in Wuhan, China, was a health crisis that greatly affected the world. Therefore, dentists and dental nurses are professionals who have a very high risk of being exposed to the droplets and aerosol particles generated during dental procedures. Furthermore, they also have a high risk of cross-infection from exposure to microorganisms in blood, saliva, droplets, and instruments contaminated with blood, saliva, and tissue debris. This study aims to analyze the effectiveness of using exhaust fan wall/Local Exhaust Ventilation (LEV), HEPA filter, and dental aerosol suction in the dental clinic of Academic Hospital Gadjah Mada University. Methods: The type of the research is analytical observational study. This study measured temperature, humidity, ACH and the microbial load in the 3 dental clinic rooms of Sadewa 1 RSA UGM in September 2020, using an analytical observational method with ANOVA to determine the effect of using a LEV, HEPA filter and dental aerosol suction in the dental clinic. Results: Dental clinic equipped with a LEV, HEPA filter, and dental aerosol suction, was negatively associated with room humidity levels, with a Pearson correlation of (-0.777), air humidity correlated with microbial load (0.242), but the correlation was not large. From the ANOVA results, the use of LEV, HEPA filter and dental aerosol suction against humidity has a significant effect on reducing the humidity in the dental clinic with p value 0.05. Conclusion: The use of an oral LEV, HEPA filter, and dental aerosol suction has an effect on reducing air humidity and decreasing the microbial load, affects the number of particles or droplets in dental clinics, and affects ACH.Keywords: local exhaust ventilation, HEPA filter and dental aerosol suction, microbial load, humidity

The vortex ventilator (VV) is a new concept of a local exhaust ventilation system that uses a vortex flow to improve the directional capture ability and thus overcomes the critical defects of the general local exhaust ventilation (LEV) system. The LEV has a rapid decrease of the capture velocity with distance from the exhaust inlet, resulting in a very poor capture efficiency when contaminants are generated far away from the exhaust inlet. In this study, the capture characteristics of the VV are evaluated with respect to the capture efficiency as well as the capture velocity. Three-dimensional computational fluid dynamics simulations are performed together with experiments using the tracer gas method with SF6. Compared with simple suction, the VV gives more than nine times as large a capture velocity and thus has a capture efficiency of higher than 70%. The larger capture velocity and the higher capture efficiency of the VV guarantee a more flexible layout of the equipment in the working area.

- In this study, we performed risk assessment of chloroprene by hazard evaluation and workplace investigation. The chemical is used to manufacture of shoes, tires, adhesives, and classified as IARC category 2B (possibly carcinogenic to humans) and target organ systemic toxicity. It is used about 1,300 tons per year in 27 sites. It was calculated the risk of carcinogenesis with chloroprene by Monte-carlo simulation that the averages are 2,199 and 26,404 in each case of working less than 15 minutes per day with local exhaust ventilation and over 4 hours per day without local exhaust ventilation. The risk of target organ systemic toxicity are 4.10 and 169.06 with high correlation with working time to be longer and with ventilation system. Therefore, it is recommended that the local exhaust ventilation and respirators to prevent occupational cancer and target organ systemic toxicity with chloroprene. Especially it is determined that there is a need to strengthen the workplace exposure limit (TWA 10 ppm) in Korea since it is managed with TWA less than 5 ppm (18 ㎎/㎥) by the United States Occupational Safety and Health Administration (OSHA) as well as it has carcinogenicity, reproductive toxicity. Key words : chloroprene, hazard, eisk assessment, dose-responseKIGAS Vol. 19, No. 3, pp 1~8, 2015 http://dx.doi.org/10.7842/kigas.20 15.19.3.1(Journal of the Korean Institute of Gas)

Chapter 6 - Commissioning, control, and maintenance of ventilation systems

Temperate buildings are comfortable, safer and more productive places to work. Ensuring that extremes of cold and heat, and airborne diseases are mitigated is through effective design, function and management of ventilation systems. This book addresses the basics of ventilation systems and their use in building-based workplaces and how to ensure they are managed successfully. This book provides comprehensive technical information regarding the design and implementation of dilution and local exhaust ventilation systems to ensure safe and productive workplaces. It presents a simple and readable summary of how to design, install, and operate industrial ventilation systems, all highlighted through illustrations and tables. This title is written to international standards on the design of dilution and local exhaust ventilation systems, including ASHRAE and ACGIH standards. Design of Workplace Dilution and Local Ventilation Systems is an ideal reference for safety engineers, designers, specialists, engineers, architects, and contractors tasked with ventilation systems. It is also a useful reference for undergraduate and graduate students to master the complex fundamentals of designing dilution and local exhaust ventilation systems.

Drilling is a common task throughout various industry sectors. When holes are drilled in silica-containing materials such as concrete, brick, and stone, respirable dust containing respirable crystalline silica (RCS) can be generated. Prolonged exposure to RCS can lead to silicosis, lung cancer, chronic obstructive pulmonary disease. Current good control practice includes the application of local exhaust ventilation (LEV) directly to the drills. This is via an external extraction system fitted to a shroud which extracts the dust generated during drilling. For several years, integrated LEV has been available for drills. Integrated LEV offers advantages over external LEV by providing increased portability, interlocked control, reduced trip hazards and reduced costs. However, little is known regarding the control effectiveness of integrated systems. The capture efficiency of 4 different integrated extractors and 1 external extraction system for controlling dust was measured using a real time respirable dust monitor. Furthermore, for 1 drill personal air sampling was conducted to assess the exposure potential to respirable dust from drilling repeatedly into concrete over a 1-h period using no LEV, integrated LEV, and external LEV options. The capture efficiency for respirable dust for 4 integrated drill LEV units ranged between 98.6% and 99.6%. This was comparable to the respirable dust capture efficiency provided by a self-sealing shroud fitted to an external extraction unit which provided efficiencies between 99.4% and 99.8%. The personal exposure testing showed respirable dust exposure was reduced by 87.6% for integrated LEV and 93.3% for external LEV fitted with a self-sealing shroud. The reason for the lower efficiency for the integrated LEV was attributed to dust generated as their dust bins were emptied more often throughout the tests. Given the size of the integrated LEV dust bins and the frequency at which they may require emptying, appropriate control measures to protect workers from dust exposure should be considered-eg emptying the units outdoors in conjunction with RPE.

Comparative analysis of indoor air quality in green office buildings of varying star levels based on the grey method

It is becoming increasingly necessary to improve people's daily living environments for their quality of life. Indoor air quality is also important, as most people spend a lot of time indoors. It is known that a significant proportion of indoor pollution is caused by outdoor pollution. However, the size of the outdoor influence may depend on the characteristics of indoor space. In this paper, we collected air and environmental data for 21 spaces and analyzed how much they relate to external environmental pollution. The result shows that the influence on the external environment varies greatly depending on the spaces.

Indoor air quality (IAQ) analysis takes into consideration several pollutants: chemical and biological elements, moisture, carbon dioxide (CO2), carbon monoxide (CO), dust, etc. Carbon dioxide (CO2) is strictly related to people's breathing, age, kind of activity and crowding in a building and it can be used as an IAQ index. In this paper, we describe CO2 evaluation and IAQ perception in a kindergarten attended by 4- and 5-year-old children and located in Reggio Emilia (Italy). We report monitoring results based on two different indicators: (a) CO2 concentration measured and monitored in the classrooms and (b) children's IAQ perception evaluated with a questionnaire. This new approach involves a psycho-pedagogical aspect of IAQ: how do children perceive IAQ? Can their behaviour or opinion represent a CO2 marker? The questionnaire helped us in understanding children's IAQ perception. The comparison between the subjective judgment resulting from the questionnaire and IAQ monitoring through a data logger shows a non-linear relationship. Children understood the IAQ concept, but they did not relate it to tiredness, breathing or allergy. They simply connected the IAQ to the smell of the air.

This work characterized airborne particles generated from the weighing of bulk, multiwall carbon nanotubes (CNTs) and the manual sanding of epoxy test samples reinforced with CNTs. It also evaluated the effectiveness of three local exhaust ventilation (LEV) conditions (no LEV, custom fume hood, and biosafety cabinet) for control of particles generated during sanding of CNT-epoxy nanocomposites. Particle number and respirable mass concentrations were measured using an optical particle counter (OPC) and a condensation particle counter (CPC), and particle morphology was assessed by transmission electron microscopy. The ratios of the geometric mean (GM) concentrations measured during the process to that measured in the background (P/B ratios) were used as indices of the impact of the process and the LEVs on observed concentrations. Processing CNT-epoxy nanocomposites materials released respirable size airborne particles (P/B ratio: weighing = 1.79; sanding = 5.90) but generally no nanoparticles (P/B ratio ∼1). The particles generated during sanding were predominantly micron sized with protruding CNTs and very different from bulk CNTs that tended to remain in large (>1 μm) tangled clusters. Respirable mass concentrations in the operator's breathing zone were lower when sanding was performed in the biological safety cabinet (GM = 0.20 μg/m3 compared with those with no LEV (GM = 2.68 μg/m3 or those when sanding was performed inside the fume hood (GM = 21.4 μg/m3; p-value < 0.0001). The poor performance of the custom fume hood used in this study may have been exacerbated by its lack of a front sash and rear baffles and its low face velocity (0.39 m/sec).

An integrated device for rapid analysis of indoor air quality in farms: The cases of milking parlors and greenhouses for baby leaf cultivation

Comparative analysis of indoor air quality in offices with different ventilation mechanisms and simulation of ventilation process utilizing system dynamics tool.

This research investigated the efficacy of machine enclosures in reducing employee exposures to metalworking fluid mist. Four hundred fifty-five personal samples from automotive machining and grinding operations collected over six years were divided into three groups based on the type and extent of enclosure and local exhaust ventilation. The sample groups were (1) machining equipment with original equipment manufacturer (OEM) total enclosures and local exhaust ventilation, (2) machining equipment with partial or retrofit enclosures and local exhaust ventilation, and (3) machining equipment with little or no enclosure. The results of the Mann Whitney U test of the three data sets indicated that the employees operating equipment with OEM enclosures had significantly lower exposures than employees operating equipment that had either of the other two control methods. There was no difference between the exposures of operators of equipment with retrofit enclosures compared to operators of equipment without enclosures. The median exposure for operators of equipment with OEM enclosures was 0.21 mg/m3, about half that found with the other two control methods. Each of the data sets was compared to exposure criteria; 100% of the exposures associated with OEM enclosures were below 1.0 mg/m3, and 90% of the exposures were below 0.5 mg/m3. The other two methods were not as effective as OEM in reducing exposure to below these criteria. These results indicate that OEM enclosures provide the most effective control of metalworking fluid mist exposure.

ABSTRACTThe purpose of this study was to compare personal exposures to isoflurane from participants' breathing zone samples during animal anesthesia procedures by the method of anesthetic gas delivery and the waste anesthetic gas (WAG) control method utilized. WAG control methods included passive scavenging using charcoal canisters, active scavenging using a building vacuum system, and various local exhaust ventilation systems such as laboratory fume hoods and capture hoods. Methods of anesthesia delivery included induction chambers, face masks (also known as nose cones), and intubation. Personal breathing zone samples were collected using 3M 3520 Organic Vapor Diffusion Monitors and submitted to an International Organization for Standardization (ISO) 17025 accredited laboratory for analysis.When using face masks and induction chambers as the method of anesthesia delivery, local exhaust ventilation systems were found to be the best WAG control method to mitigate personal exposures to isoflurane. Personal exposures to isoflurane were well-controlled when animals were intubated, regardless of whether passive scavenging with an adsorptive charcoal canister or active scavenging with a building vacuum system was used. Personal exposures to isoflurane were highest when induction chambers and face masks were used for anesthesia delivery, and passive scavenging with adsorptive charcoal canisters were used as the control method. This study served to identify best practice WAG control methods for research and veterinary procedures that involve isoflurane anesthesia.