breathing zone
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Author(s):  
Дмитрий Валерьевич Лобанов ◽  
Игорь Иванович Звенигородский ◽  
Александр Александрович Мерщиев ◽  
Роман Александрович Шепс

Умственный труд достаточно разнообразен и характеризуется различной степенью ответственности, монотонности, внимания, уровнем эмоционального напряжения. Для обеспечения комфортных условий пребывания человека на постоянном рабочем месте, необходимо в том числе организовывать системы климатизации. Наиболее перспективными для указанной деятельности, являются персональные системы вентиляции, обеспечивающие качественную воздушную среду в зоне дыхания человека при одновременном снижении капитальных и эксплуатационных затрат по сравнению с традиционными видами систем вентиляции (смешивающая, вытесняющая вентиляция). Однако, при проектировании таких систем следует ориентироваться не на «среднего условного человека», а учитывать индивидуальные особенности работника (возраст, пол и др.), выполняющего конкретный вид умственной деятельности. С целью уточнения фактической величины углекислого газа, выделяемого человеком при определенной умственной работе, проведены натурные экспериментальные исследования, результатом которых является подтверждение характера и динамики изменения углекислого газа в помещении при отсутствии (бездействии) вентиляционных систем (линейная зависимость), а также уточнение величины выделяющейся двуокиси углерода при конкретном виде умственной деятельности (исследовался труд инженера-проектировщика). Intellectual work is quite diverse and is characterized by different degrees of responsibility, monotony, attention, the level of emotional tension. In order to ensure comfortable conditions for a person staying at a permanent workplace among other things it is necessary to arrange climate control systems. The most promising ventilation systems for the above activities are personal ones that provide high-quality air environment in the breathing zone of a person while reducing capital and operating costs compared with traditional types of ventilation systems (mixing, displacement ventilation). However, the design of such systems should be guided not by the "average conditional person" but by the individual characteristics of the worker (age, gender, etc.) performing a particular type of mental activity. In order to clarify the actual value of carbon dioxide emitted by a person doing a particular mental work, we conducted a series of field experimental studies. They resulted in confirmation of the nature and dynamics of changes in carbon dioxide in the room in the absence (inactivity) of ventilation systems (linear dependence). As well we clarified the value of emitted carbon dioxide at a particular type of mental activity (in this article we studied the work of an engineer-designer).


Electronics ◽  
2021 ◽  
Vol 10 (24) ◽  
pp. 3069
Author(s):  
Haiying Wang ◽  
Lin Wang ◽  
Heechan Kang ◽  
Moon-Hyon Hwang ◽  
Do Gyun Lee ◽  
...  

Recently, increasing numbers of people have realized the harm that particulate matter (PM) causes to health, especially those with a diameter less than 2.5 μm (PM2.5). With the increasing popularity of wearable devices in recent years, it is believed that wearable technology can contribute feasible solutions to prevent health hazards caused by PM2.5. In order to better understand the public’s needs regarding wearable devices, this study aimed to determine what kinds of PM2.5 wearable devices were needed by the public and the factors that may influence these needs. An online survey was conducted in the Beijing metropolitan area of China of a total of 894 subjects. The results showed that the public’s overall need for wearable PM2.5 purifiers was higher than for wearable PM2.5 trackers. The public’s needs for wearable breathing-zone PM2.5 devices were significantly higher than for any other type, indicating that people care about the quality of the air they actually breathe. It was also found that education, income level, and attitude toward PM2.5 positively affected their needs for wearable devices. In contrast, age had a negative influence on their needs. The results of this study are expected to serve as a valuable reference for related academic and industrial research.


Author(s):  
Carla J. Olave ◽  
Kathleen M. Ivester ◽  
Laurent L. Couëtil ◽  
Jackeline Franco-Marmolejo ◽  
Abhijit Mukhopadhyay ◽  
...  

Abstract OBJECTIVE To investigate the role of omega-3 polyunsaturated fatty acids (Ω-3)–derived proresolving lipid mediators (PRLM) in the resolution of mild airway inflammation in horses. ANIMALS 20 horses with mild airway inflammation. PROCEDURES Horses previously eating hay were fed hay pellets (low Ω-3 content; n = 10) or haylage (high Ω-3 content; 9) for 6 weeks. Dust exposure was measured in the breathing zone with a real-time particulate monitor. Bronchoalveolar lavage (BAL) was performed at baseline, week 3, and week 6. The effect of PRLM on neutrophil apoptosis and efferocytosis was examined in vitro. BAL fluid inflammatory cell proportions, apoptosis of circulating neutrophils, efferocytosis displayed by alveolar macrophages, and plasma lipid concentrations were compared between groups fed low and high amounts of Ω-3 by use of repeated measures of generalized linear models. RESULTS Dust exposure was significantly higher with hay feeding, compared to haylage and pellets, and equivalent between haylage and pellets. BAL fluid neutrophil proportions decreased significantly in horses fed haylage (baseline, 11.8 ± 2.4%; week 6, 2.5 ± 1.1%) but not pellets (baseline, 12.1 ± 2.3%; week 6, 8.5% ± 1.7%). At week 6, horses eating haylage had significantly lower BAL neutrophil proportions than those eating pellets, and a significantly lower concentration of stearic acid than at baseline. PRLM treatments did not affect neutrophil apoptosis or efferocytosis. CLINICAL RELEVANCE Despite similar reduction in dust exposure, horses fed haylage displayed greater resolution of airway inflammation than those fed pellets. This improvement was not associated with increased plasma Ω-3 concentrations. Feeding haylage improves airway inflammation beyond that due to reduced dust exposure, though the mechanism remains unclear.


PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0246916
Author(s):  
Sean M. Kinahan ◽  
David B. Silcott ◽  
Blake E. Silcott ◽  
Ryan M. Silcott ◽  
Peter J. Silcott ◽  
...  

The COVID-19 pandemic has reintroduced questions regarding the potential risk of SARS-CoV-2 exposure amongst passengers on an aircraft. Quantifying risk with computational fluid dynamics models or contact tracing methods alone is challenging, as experimental results for inflight biological aerosols is lacking. Using fluorescent aerosol tracers and real time optical sensors, coupled with DNA-tagged tracers for aerosol deposition, we executed ground and inflight testing on Boeing 767 and 777 airframes. Analysis here represents tracer particles released from a simulated infected passenger, in multiple rows and seats, to determine the exposure risk via penetration into breathing zones in that row and numerous rows ahead and behind the index case. We present here conclusions from 118 releases of fluorescent tracer particles, with 40+ Instantaneous Biological Analyzer and Collector sensors placed in passenger breathing zones for real-time measurement of simulated virus particle penetration. Results from both airframes showed a minimum reduction of 99.54% of 1 μm aerosols from the index source to the breathing zone of a typical passenger seated directly next to the source. An average 99.97 to 99.98% reduction was measured for the breathing zones tested in the 767 and 777, respectively. Contamination of surfaces from aerosol sources was minimal, and DNA-tagged 3 μm tracer aerosol collection techniques agreed with fluorescent methodologies.


Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7570
Author(s):  
Zhonghua Zhang ◽  
Lingjie Zeng ◽  
Huixian Shi ◽  
Gukun Yang ◽  
Zhenjiang Yu ◽  
...  

The poor indoor air quality (IAQ) of severely polluted toilets is associated with increased risk of severe disease. This study aimed to evaluate the overall IAQ according to the contaminant removal efficiency, volume average concentration, and breathing zone control level. The characteristics of contaminant transmission in a non-flushing ecological toilet (NFET) were analyzed using the computational fluid dynamics (CFD) methodology, and the proposed model was further validated based on experimental measurements. Both an orthogonal experimental design and CFD were used to analyze factors such as exhaust fan position (EFP), air change rate per hour (ACH), natural vent location (NVL), and grid height (G-h). The EFP and ACH were demonstrated to be the dominant factors affecting the IAQ, whereas NVL and G-h were found to play key roles. Single-factor analysis based on the significance levels of the ACH, EFP, and NVL was conducted using the CFD methodology to define three exhaust behaviors—namely, “ineffective”, “enhanced”, and “excessive”. These results provide key insights that may be used to improve the IAQ of NFETs.


2021 ◽  
pp. 002203452110562
Author(s):  
J.R. Allison ◽  
C. Dowson ◽  
K. Pickering ◽  
G. Červinskytė ◽  
J. Durham ◽  
...  

Dental procedures produce aerosols that may remain suspended and travel significant distances from the source. Dental aerosols and droplets contain oral microbes, and there is potential for infectious disease transmission and major disruption to dental services during infectious disease outbreaks. One method to control hazardous aerosols often used in industry is local exhaust ventilation (LEV). The aim of this study was to investigate the effect of LEV on aerosols and droplets produced during dental procedures. Experiments were conducted on dental mannequins in an 825.4-m3 open-plan clinic and a 49.3-m3 single surgery. Ten-minute crown preparations were performed with an air-turbine handpiece in the open-plan clinic and 10-min full-mouth ultrasonic scaling in the single surgery. Fluorescein was added to instrument irrigation reservoirs as a tracer. In both settings, optical particle counters (OPCs) were used to measure aerosol particles between 0.3 and 10.0 µm, and liquid cyclone air samplers were used to capture aerosolized fluorescein tracer. In addition, in the open-plan setting, fluorescein tracer was captured by passive settling onto filter papers in the environment. Tracer was quantified fluorometrically. An LEV device with high-efficiency particulate air filtration and a flow rate of 5,000 L/min was used. LEV reduced aerosol production from the air-turbine handpiece by 90% within 0.5 m, and this was 99% for the ultrasonic scaler. OPC particle counts were substantially reduced for both procedures and air-turbine settled droplet detection reduced by 95% within 0.5 m. The effect of LEV was substantially greater than suction alone for the air-turbine and was similar to the effect of suction for the ultrasonic scaler. LEV reduces aerosol and droplet contamination from dental procedures by at least 90% in the breathing zone of the operator, and it is therefore a valuable tool to reduce the dispersion of dental aerosols.


2021 ◽  
Vol 5 (2) ◽  
pp. 904-917
Author(s):  
Anita Maria Magdalena Silaban ◽  
Mila Tejamaya

Measurement of nanoparticles in the personal breathing zone (PBZ) is an effort to assess the risk of nanoparticle exposure in the workplace. Can be done with Direct-Reading as a monitor effort. Indonesia, as one of the countries that also participates in the use of nanotechnology, requires a measurement method that is appropriate to its conditions. Methods: this systematic literature review examines direct-reading methods. Result: two types of instruments were found for direct reading. Results: by conducting an assessment in accordance with the conditions of the Indonesian state, this study recommends Condensation particle counter (CPC) as an instrument that can be used


Author(s):  
Shijun Wei ◽  
Belinda Johnson ◽  
Michael Breitenstein ◽  
Lina Zheng ◽  
John Snawder ◽  
...  

Abstract A method for aerosol chemical analysis using handheld Raman spectrometer has been developed and its application to measurement of crystalline silica concentration in workplace atmosphere is described. The approach involves collecting aerosol as a spot sample using a wearable optical aerosol monitor, followed by direct-on-filter quantitative analysis of the spot sample for crystalline silica using handheld Raman spectrometer. The filter cassette of a commercially available optical aerosol monitor (designed to collect aerosol for post-shift analysis) was modified to collect 1.5-mm-diameter spot sample, which provided adequate detection limits for short-term measurements over a few tens of minutes or hours. The method was calibrated using aerosolized α-quartz standard reference material in the laboratory. Two Raman spectrometers were evaluated, one a handheld unit (weighing less than 410 g) and the other a larger probe-based field-portable unit (weighing about 5 kg). The lowest limit of quantification for α-quartz of 16.6 μg m−3 was obtained using the handheld Raman unit at a sample collection time of 1 h at 0.4 l min−1. Short-term measurement capability and sensitivity of the Raman method were demonstrated using a transient simulated workplace aerosol. Workplace air and personal breathing zone concentrations of crystalline silica of workers at a hydraulic fracturing worksite were measured using the Raman method. The measurements showed good agreement with the co-located samples analyzed using the standard X-ray powder diffraction (XRD) method, agreeing within 0.15–23.2% of each other. This magnitude of difference was comparable to the inter- and intra-laboratory analytical precision of established XRD and infrared methods. The pilot study shows that for silica-containing materials studied in this work it is possible to obtain quantitative measurements with good analytical figures of merit using handheld or portable Raman spectrometers. Further studies will be needed to assess matrix interferences and measurement uncertainty for several other types of particle matrices to assess the broader applicability of the method.


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