Room Size Research Articles

Verification and Optimization of an Ultra-low Volume (ULV) Sprayer Used for the Inactivation of Indoor Total Bacteria

BACKGROUND AND AIM: Physical and chemical cleaning to remove indoor microorganisms, which cause allergic reactions and respiratory diseases, is labor-intensive and time-consuming. An ultra-low volume (ULV) sprayer, a newly introduced device to inactivate pathogenic microorganisms, allows the disinfectant particles to reach hard-to-reach spaces indoors and is more cost-effective than the existing methods. However, few studies have been conducted to verify the efficiency of the ULV sprayer. We aimed to verify the disinfection efficiency of the ULV sprayer for inactivating total bacteria indoors, considering the factors affecting bacteria inactivation, and present the optimal ULV sprayer usage conditions to achieve the highest disinfection efficiency depending on room size. METHODS: Two-stage experiments were conducted. Total bacteria were grown in broth culture, seeded into biofilm templates, and placed in each location. VirkonTM Micro was dispersed into the rooms. Samples were collected pre-and post-spraying using Rodac plates to evaluate the disinfection efficacy. A response surface model was developed to optimize usage conditions for bacterial inactivation. RESULTS:The total bacteria removal efficiency was high (0.56 – 2.46 log10 reductions), including hard-to-reach spaces. The disinfectant concentration, spray amount, and room size had interactive effects on the total bacteria disinfection efficiency. The experimental data were fitted to a second-order polynomial model, with high coefficients of determination (R2) for all models (R2 0.82). The optimum conditions were a spray amount of 3.08 – 6.40 L in 160 m3, 3.78 – 7.22 L in 230 m3, and 5.68 – 8 L in 300 m3 when using dilution rates of 100 times. These conditions predicted a bacterial disinfection efficiency of 1.10 log10 reductions (92%) on all surfaces. CONCLUSIONS:Our results clearly indicate that the ULV sprayer effectively inactivates total bacteria indoors. The study results can be used as basic data for effective control of indoor surface microbes using ULV sprayer based on quantitative evidence. KEYWORDS: Built environment, Particle components, Microbes

Exploration on Research Methods for Exploring Human Response to Luminous Environment with Chromogenic Windows Applied

Chromogenic windows enable both energy-saving and daylighting regulation. However, the human response to the luminous environment affected by them is difficult to test, since their features of dynamic change and tinting automatically. This study explores the research methods, including experimental design and statistical analysis, by literature review and an experiment demonstration. The results show that a proper size of the test room is significant to obtain desired data, and the advanced VR technologies have the potential to be applied for testing these dynamic variables. Bayesian approaches are recommended to be tried and get more accurate interference about the experimental results.

241. Does OR size impact spine surgery efficiency?

<h3>BACKGROUND CONTEXT</h3> Increased operative duration, in addition to time under anesthesia, has been shown to increase the risk of intraoperative and postoperative complications. The specific relationship between operating room size and prolonged surgical duration in spine surgery has yet to be explored. <h3>PURPOSE</h3> To determine if operating room (OR) size is independently associated with extended duration of spine surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study. <h3>PATIENT SAMPLE</h3> All patients over age 18 who underwent any primary or revision decompression or fusion for degenerative spinal pathologies at a single academic institution were retrospectively identified. Patients with a traumatic injury, infection, malignancy, or incomplete surgical timing parameters were excluded. <h3>OUTCOME MEASURES</h3> Surgical case extension. Surgical case delay. <h3>METHODS</h3> A retrospective cohort analysis of patients undergoing spine surgery for degenerative pathologies at a high-volume academic center was performed. Operating room timing parameters including theater time, duration under anesthesia, and procedural time were recorded. Surgical case delay and surgical case extension were calculated through deviations from the scheduled case start time and expected case duration. Operating rooms were dichotomized into large and small groups based on size above or below mean square footage. Univariate analysis compared patient demographics and surgical factors across large and small OR groups. The relationship between OR size and minutes of case delay and case extension was evaluated. <h3>RESULTS</h3> A total of 4,178 patient surgeries met the inclusion criteria. Patient demographics, medical comorbidities, and surgical characteristics did not vary meaningfully between large and small OR groups. Patients undergoing surgery in large ORs experienced significantly greater prolongation in case duration (actual theater time - scheduled theater time). When cases with extended duration were compared to equivalent cases adhering to expected duration parameters, procedure time and time under anesthesia remained significantly greater in large operating rooms. Extension in theater time was found to vary independently from delay in surgical start time as delay time was statistically equivalent between OR groups. <h3>CONCLUSIONS</h3> Spine surgery in larger ORs was shown to correlate with extended procedural duration. Larger operating rooms may decrease surgical efficiency. Further research is required to determine if operating size independently predicts prolonged surgery and adverse outcomes. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

The Physical Hospital Environment and Its Effects on Palliative Patients and Their Families: A Qualitative Meta-Synthesis.

To review the latest qualitative literature on how the physical hospital environment affects palliative patients and their families. People with a life-limiting illness may receive palliative care to improve their quality of life in hospital and may have multiple admissions as their illness progresses. Yet, despite a preference for a death at home, more than half of the dying population will receive end-of-life care in hospital. The physical hospital environment consists of ambiance, aesthetics, and architectural factors, and it is well known that the hospital's acute wards are not a homely environment. Demand is increasing for the physical environment to be improved to better meet the needs and demands of palliative and end-of-life patients and their families. Combining thematic analysis and meta-ethnography methodologies, 12 international qualitative papers were analyzed and synthesized by the three authors. Findings resulted in the development of the SSAFeR Place approach that incorporates the concepts that are important to palliative and end-of-life patients and their families by describing an environment within the acute or palliative care units that feels safe, is private, customizable, and accommodates family; is a space to share with others, is homelike in ambiance and aesthetics, and is conducive for reflection. The concepts of identity, belonging, and safety are connected to the notions of home. To provide person-centered care and to move the focus toward the palliative approach of comfort and quality of life, attention to room size, layout, aesthetics, and ambiance is needed.

Design and simulation of acoustics for the home theatre

As a typical acoustics room, the sound quality of home theatre is an important standard to evaluate its design. Qualified acoustics design is the guarantee of good sound quality. The volume of home theatre is generally small, so the room size is similar to the low-frequency wavelength. Then the resonance will occur when the excitation of the sound source frequency acts on the natural resonance frequency of the room. At the same time, the secondary reflection of the room also interferes the direct sound emitted by the speaker, thus destroying the sound image. In order to solve the above problems, this paper took a home theatre as an example, analyzed the normal modes of the room by the theory of wave acoustics, and then made an acoustics design and simulation. The simulation results showed that the reverberation time was up to the relevant standards and the room acoustic quality environment was improved obviously after the acoustic design.

Room Size Influences Flow in Robotic-Assisted Surgery.

The introduction of surgical technology into existing operating rooms (ORs) can place novel demands on staff and infrastructure. Despite the substantial physical size of the devices in robotic-assisted surgery (RAS), the workspace implications are rarely considered. This study aimed to explore the impact of OR size on the environmental causes of surgical flow disruptions (FDs) occurring during RAS. Fifty-six RAS procedures were observed at two academic hospitals between July 2019 and January 2021 across general, urologic, and gynecologic surgical specialties. A multiple regression analysis demonstrated significant effects of room size in the pre-docking phase (t = 2.170, df = 54, β = 0.017, p = 0.035) where the rate of FDs increased as room size increased, and docking phase (t = −2.488, df = 54, β = −0.017, p = 0.016) where the rate of FDs increased as room size decreased. Significant effects of site (pre-docking phase: p = 0.000 and docking phase: p = 0.000) were also demonstrated. Findings from this study demonstrate hitherto unrecognized spatial challenges involved with introducing surgical robots into the operating domain. While new technology may provide benefits towards patient safety, it is important to consider the needs of the technology prior to integration.

Development Of Electrical Installation Learning Me-dia With Delphi Language

Learning Media is a learning tool that is used by someone by using tools that are made to facilitate the delivery of material when teaching at school. Things like that really help teachers in teaching in schools and are a solution to make students happy when learning and not feel bored. One of the learning materials in Vocational High Schools is electrical installation material. Introducing electrical installation material will be very difficult if only with books. Therefore this study aims to adopt material about electrical installations in a computer system. This system is called the Electrical Installation Learning Media in Delphi Language. This system is used to determine the number of light points on an electrical installation from the room size indicator and the amount of lux to be achieved. In addition, the system provides a brief description of the electrical installation material. In this system the electrical installation input data is entered into the computer manually. In building this system, Delphi 7 and Inno Set Up Compiler software are used as installers. The method used in this research is Research and Development (R&amp;D), with the following stages: (1) preliminary research; (2) designing software; (3) collection of materials; (4) initial product development; (5) validation of instructional media experts; (6) product analysis and revision; (8) testing the media in learning; and (9) the final product of the instructional media. The results show that: (1) the results of the feasibility test according to electrical installation experts are that this system is suitable to be used as a learning medium in electrical installation subjects in vocational schools because it contains an explanation of the calculation method of an electrical installation in detail; (2) the results of the feasibility test according to media experts are that this system has very attractive visuals, is user friendly, is compatible with Windows and Linux and the media size is not too large; and (3) the results of the experiment using an indication of the size of the room and the amount of lux to be achieved, obtained data on the number of lamps according to the calculation using the formula.

Risk Assessment of Infection by Airborne Droplets and Aerosols at Different Levels of Cardiovascular Activity

Since end of 2019 the COVID-19 pandemic, caused by the SARS-CoV-2 virus, is threatening humanity. Despite the fact that various scientists across the globe try to shed a light on this new respiratory disease, it is not yet fully understood. Unlike many studies on the geographical spread of the pandemic, including the study of external transmission routes, this work focuses on droplet and aerosol transport and their deposition inside the human airways. For this purpose, a digital replica of the human airways is used and particle transport under various levels of cardiovascular activity in enclosed spaces is studied by means of computational fluid dynamics. The influence of the room size, where the activity takes place, and the aerosol concentration is studied. The contribution aims to assess the risk of various levels of exercising while inhaling infectious pathogens to gain further insights in the deposition behavior of aerosols in the human airways. The size distribution of the expiratory droplets or aerosols plays a crucial role for the disease onset and progression. As the size of the expiratory droplets and aerosols differs for various exhaling scenarios, reported experimental particle size distributions are taken into account when setting up the environmental conditions. To model the aerosol deposition we employ text{OpenFOAM} by using an Euler-Lagrangian frame including Reynolds-Averaged Navier–Stokes resolved turbulent flow. Within this study, the effects of different exercise levels and thus breathing rates as well as particle size distributions and room sizes are investigated to enable new insights into the local particle deposition in the human airway and virus loads. A general observation can be made that exercising at higher levels of activity is increasing the risk to develop a severe cause of the COVID-19 disease due to the increased aerosolized volume that reaches into the lower airways, thus the knowledge of the inhaled particle dynamics in the human airways at various exercising levels provides valuable information for infection control strategies.

STOP &amp; STARE: STUDI KASUS PERILAKU PENGGUNA RUANG DURIAND BINTARO

Durian specialty restaurant is a restaurant that sells a variety of durians and souvenirs. One of the durian specialty restaurants is DuriAnd Bintaro. In the way of payment and order, the Quality Control stage is a unique part of this restaurant. This stage presents a pattern of behavior that is different from other restaurants. There is a special ‘talented’ restaurant staff at the Quality Control table to recommend the perfect durian to be purchased. In the other hand, this stage affects the rest of order and payment method. The Quality Control stage takes a lot of time which can result in customer buildup in the space, waiting for their turn to order. However, this stage is an important part because it will decide the quality of the durian that customers will eat. Qualitative research methods with literature studies, visits and interviews were carried out to analyze behaviors of all related actors. The study found that space that holds “stop &amp; stare” activity during quality control stage in similar restaurant needs to consider the room size and interior layout to accommodate the situation.

Estimate of the critical exposure time based on 70 confirmed COVID-19 cases.

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 effect of opening windows on the airflow distribution inside naturally ventilated residential bedrooms with ceiling fans

Ceiling fans are the most common equipment in any household with electricity to induce a higher air movement since the potential of natural ventilation is limited. However, the higher airflow region is generally limited to the zone below the fan. The non-uniform distribution of airflow is also affected by the furniture layout and airflow from window openings. This study attempts to evaluate the effect of the different window-opening patterns on the airflow inside naturally ventilated bedrooms, having a ceiling fan for air movement with numerical simulations and on-site measurements. The airflow pattern created by a ceiling fan in a room with furniture is modelled and simulated with ANSYS Fluent 2019 R3. The results were validated with on-site measurements and compared with the literature. The air velocity was measured in bedrooms of three different sizes. It was observed that the opening of windows created a better distribution of air irrespective of room size. The non-uniformity of the air velocity is reduced from 76% to 39% with the opening of windows in the larger-sized room. The reduction in non-uniformity is influenced by the location of windows also. The practice of opening windows along with the induced air movement by ceiling fans results in a better distribution of air in the space. Practical application: People tend to depend mainly on ceiling fans even if windows are open in naturally ventilated rooms. A study of patterns of non-uniform distribution of airflow can help designers to improve comfort conditions by specifying the number and location of fans and windows while designing room furniture layout. This aids the building services engineers to provide thermal comfort without always depending on alternative active ventilation strategies.

Management of trauma to the anterior segment of the maxilla: alveolar fracture and primary incisors crown and root fracture

Background: An injury to both the primary and permanent teeth and the supporting structures is one of the most common dental problems seen in children. Splinting is usually difficult or impossible to perform in the primary dentition (due to diminutive room size and lack of patient cooperation). Healing must, therefore, occur despite mobility at the fracture line, usually resulting in interposition of connective tissue. In some instances, infection will occur in the coronal pulp. The present study reported a case of trauma to the anterior primary teeth and alveolar bone in a four year old child. The trauma has caused fracture to the crowns and roots of the primary anterior teeth. The following case was managed in a procedure that may provide primary teeth subjected to trauma a better chance than extraction with a better prognosis. Case presentation: a 4 and a half year old child was subjected to trauma in anterior segment of maxilla. Suturing of the torn soft tissue was the first step followed by pulpotomy for the left primary lateral incisor. Fixation of the right primary central and lateral incisors was done by acid etch wire fixation. Both clinical and radiographic follow up was carried out for 6.4 years. Results: healing of the soft tissue was observed after one week and completed after two months. Fixation of the teeth continued for ten months. The fracture lines in the roots remained in position. Clinically there was no sign of any pulpal inflammation or necrosis. Radiographically, no signs of infection to the surrounding tissues could be seen, no resorption in the alveolar bone, external or internal resorption of the root did not happen also. After ten months fixation ended and the wire was removed. At that time there was normal resorption of the roots of the primary incisors in relation with the normal development of the permanent incisors. After 3 years both permanent central incisors erupted in their normal position. After 6.4 years all four permanent incisors erupted into occlusion in their normal position. Conclusion: primary teeth with root fractures and severely mobile coronal fragments can be treated by a conservative approach. The severity of the sequels is directly related to the degree of permanent tooth formation (child’s age), type of dental trauma and extent of the impact.

Products of Interest

Products of Interest

Thermal Analysis on Heat Pump Chili Drying Chamber with variations in the direction of air flow using Computational Fluid Dynamics

Drying chilies using a heat pump includes drying at low temperatures so that the temperature distribution and flow direction in the drying chamber need to be considered. The distribution of temperature and flow direction in the heat pump drying room with a drying room size of 1 m × 0.8 m × 0.75 m to dry 1 kg of chilies built in the Sustainable Energy and Research Center (SERC) laboratory is not good enough to make the drying time longer. The procedure has been established with the aim of evaluating the speed distribution and temperature of the drying air in the drying chamber to determine the need for redesign. Computational Fluid Dynamics (CFD) is used to analyze flow patterns that occur in the drying chamber where in this study two types of flow directions that enter the heat pump chili drying chamber are compared. CFD has replaced the classical numerical analysis method of drying processes based on experimental models. Analytical methods and experimental methods are limited in describing the distribution of temperature and air flow in the drying chamber. In this case, the finite element method is used in the form of CFD analysis where the geometry of the drying chamber is divided into several analyzed elements. After doing the CFD simulation, it is obtained that the heat pump chili drying chamber model with the flow direction from below the temperature increases faster than the heat pump chili drying chamber model with the flow direction from the side. The simulation results show that the drying room with the direction of hot air flow from below, the temperature of the dried chilies increases faster and the temperature distribution is better than the drying room with the flow direction from the side. In both models of the drying chamber, the temperature value is obtained in the timestep 600, namely in the drying chamber model with hot air flow from the side is 305,569 K and in the drying chamber model with hot air flow from below is 313,697 K. For the drying model in this heat pump chili drying room it is advisable to use the flow direction from below because it is better. This solution can also be offered to get the right drying chamber model.

Factors Affecting Auditory Estimates of Virtual Room Size: Effects of Stimulus, Level, and Reverberation.

When vision is unavailable, auditory level and reverberation cues provide important spatial information regarding the environment, such as the size of a room. We investigated how room-size estimates were affected by stimulus type, level, and reverberation. In Experiment 1, 15 blindfolded participants estimated room size after performing a distance bisection task in virtual rooms that were either anechoic (with level cues only) or reverberant (with level and reverberation cues) with a relatively short reverberation time of T60 = 400 milliseconds. Speech, noise, or clicks were presented at distances between 1.9 and 7.1 m. The reverberant room was judged to be significantly larger than the anechoic room (p < .05) for all stimuli. In Experiment 2, only the reverberant room was used and the overall level of all sounds was equalized, so only reverberation cues were available. Ten blindfolded participants took part. Room-size estimates were significantly larger for speech than for clicks or noise. The results show that when level and reverberation cues are present, reverberation increases judged room size. Even relatively weak reverberation cues provide room-size information, which could potentially be used by blind or visually impaired individuals encountering novel rooms.

Exposition of respiratory ailments from trace metals concentrations in incenses

Selected trace metals of importance in different incense before and after the smoldering process were assessed based on the recent respiratory ailments. Marketed perfumed and non-perfumed incense from different countries was separately analyzed using an Inductive coupled Plasma-Mass Spectroscopy (ICP-MS). A particulate analyzer measured the dispersed particulates (PM2.5) in the indoor environment. The analysis revealed higher mean metals concentrations in the smoldered perfumed incense (1.98 µg g−1) than in the non-smoldered and non-perfumed incense (0.59 µg g−1). Pilot-scale experiments included the smoke dispersed in different sized-rooms, and the distance between the inhaler and the smoldering incense. Simultaneously, a questionnaire distributed to 300 residents from six sampling areas revealed the exposure of incense to human health. This study indicated significant attributes on (a) the room size and incense volume, (b) the permissible inmate’s number in a room, (c) the distance between the inmate vicinity and the point of smoldering incense, (d) selectivity of incense, besides the outdoor environmental influence. Furthermore, this study revealed the various categories of respiratory ailments in residents in relation to the frequency of burning incense, prolonged smoke exposure, and the impact of burners although, earlier beneficial effects of incenses were evidenced. This study recommends preventive measures to human respiratory ailments from smoldering incense.

Detailed measured air speed distribution in four commercial buildings with ceiling fans

The layout of ceiling fans in buildings is challenging because of the need to co-ordinate with other elements in the ceiling space, and because the resulting airflows within the occupied space interact with furniture. This study conducted detailed air speed measurements in four buildings with different room sizes, furniture configurations, ceiling fan types, and ceiling-fan-to-floor-area ratios. We measured air speeds across the occupied spaces at four heights while varying ceiling fan operation modes such as fan rotational speed, operating direction, and the number of operating fans. In total, we collected 207,080 air speed samples at 343 sites under 20 test conditions. This paper presents the magnitude and distribution of air speeds, cooling effects, and their influencing factors. The Airspeed Coverage Index (ACI=Fanairspeed(SF)×Fandiameter(D)Averageareaservedperceilingfan(A)) describes the combined effects of multiple influencing factors on the magnitude of air speed. ACI is employed to predict the average air speed and occupant cooling effect, yielding regression confidences higher than 0.95. When designing a space to a target airspeed or cooling effect, the ACI can help to determine parameters such as fan density required for fan choices. The measured data are compared with predictions from the CBE fan tool that had been developed from laboratory tests under simplified conditions. The comparison displays the blocking effects of the furniture, lowering the average air movement in the space, as well as reducing the air movement at the ankle level while increasing it at higher heights. The blocking effect increases with the density of the furniture. We also visually present fan interactions in which triplets of fans are arranged linearly or diagonally, showing that the diagonal layout of ceiling fans increases average air speed and improves its uniformity.

Aging-in-Place: Residents' Attitudes and Floor Plan Potential in Apartment Buildings From 1990 to 2015.

We investigated apartment designs in apartment blocks built 1990-2015 in Gothenburg, Sweden. We investigated the residents' attitudes toward their previous, present, and future housing and their perceived possibilities for aging-in-place. We analyzed their apartments, focusing on the possibilities for aging-in-place in future care situations concerning bedroom capacity in a care situation; spatial proximity between bathroom, bedroom, storage, and entrance; and functional autonomy in a care situation without too much disturbance for a partner. Since the 2000s, the ambition in Sweden is to enable older people to remain in ordinary housing. The possibilities for aging-in-place should therefore be considered already in the design stage, also when producing standard apartments. Semi-structured interviews were made with 30 households, with one or more resident 65 years or older. Floor plan analyses were made of their present apartments. The majority displayed a pragmatic attitude toward aging, high satisfaction with their present housing situation, and good chances for aging-in-place in future homecare scenarios. The floor plan analysis shows that the three concepts of bedroom capacity, spatial proximity, and functional autonomy can be used to determine the potential for aging-in-place. The results suggest that architectural qualities related to aging-in-place are not automatically connected to floor size or number of rooms. Small apartments can perform better than larger ones, depending on spatio-functional organization and connections between different functions. The residents' perceived chances for aging-in-place confirm this relation. Future studies should compare different locations, production periods, and relations between size, space efficiency, and accessibility.

Prevalence and factors associated to dysphonia and laryngeal lesions: a study among teachers in a region of the Brazilian Legal Amazon

&lt;p&gt;&lt;strong&gt;Objective&lt;/strong&gt;: to investigate the prevalence and factors associated with dysphonia and laryngeal lesions in teachers of basic education in a region of the Amazonian region. &lt;strong&gt;Methods: c&lt;/strong&gt;ross-sectional study with collection of sociodemographic variables, occupational, environmental and clinics. Laryngeal lesions were evaluated by laryngoscopy. Was used a logistic regression to determine factors associated. &lt;strong&gt;Results&lt;/strong&gt;: the prevalence of dysphonia and laryngeal lesions was 68.9% and 53.3%, respectively. There was association between self-reported dysphonia and respiratory problems (OR=3.00; CI95%=1.25-7.22), use of drugs (OR= 2.31, CI95%= 1.19-4.49) and noise in the internal environment (OR= 2.43; CI95%=1.24-4.73). Easy access to water was a protection factor against self-reported dysphonia (OR=0.09; CI95%: 0.01-0.79). We found a significant association between dysphonia diagnosed and digestive problems (OR= 6.09; CI95%=2.79-13.30), external noise (OR=5.20, CI95%=1.99-13.57) and inadequate ventilation (OR=3.24; CI95%=1.36-7.74). The variables associated with higher chance of laryngeal lesions in dysphonic teachers were lighting (OR=3.74; CI95%=1.15-12.14%), acoustics (OR= 4.14; CI95%=1.32-12.95) and inadequate room size (OR= 3.76; CI95%=1.29-10.91). The use of drugs (OR=0.34; CI95%=0.12-0.92), respiratory problems (OR=0.21; CI95%=0.06-0.76) and easy access to water (OR= 0.12; CI95%=0.04-0.38) were protection factors for laryngeal lesions. &lt;strong&gt;Conclusion:&lt;/strong&gt; occupational environmental factors aggravated the vocal health of this professional category. Access to water in the work impacted positively.&lt;/p&gt;

Verification and Optimization of an Ultra-Low Volume (ULV) Sprayer Used for the Inactivation of Indoor Total Bacteria

Physical and chemical cleaning for the removal of indoor microorganisms, which can cause allergic reactions and respiratory diseases, is labor-intensive and time-consuming. An ultra-low volume (ULV) sprayer, a newly introduced device to inactivate pathogenic microorganisms, allows the disinfectant particles to reach hard-to-reach spaces indoors and is more cost-effective than the existing methods. However, few studies have been conducted to verify the efficiency of the ULV sprayer. Here, we verified the disinfection efficiency of the ULV sprayer for inactivating total bacteria present on indoor surfaces, considering the factors affecting bacteria inactivation, and presented the optimal ULV sprayer usage conditions to achieve the highest disinfection efficiency depending on room size. The total bacteria removal efficiency was high (range: 0.56–2.46 log10 reductions), including hard-to-reach spaces. A response surface model was developed to identify the individual and interactive effects of the disinfectant concentration, spray amount, and room size on total bacteria disinfection efficiency. These three variables had interactive effects on the total bacteria disinfection efficiency. The experimental data were fitted to a second-order polynomial model, with high coefficients of determination (R2) for all models (R2 &gt; 0.82). The optimum conditions were a spray amount of 3.08–6.40 L in 160 m3, 3.78–7.22 L in 230 m3, and 5.68–8 L in 300 m3 surface area when using dilution rates of 100 times. These conditions predicted a bacterial disinfection efficiency of &gt;1.10 log10 reductions (92%) on all surfaces. Our results clearly indicate that the ULV sprayer effectively inactivates total bacteria present on indoor surfaces.