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1.
AORN J ; 113(3): P5-P8, 2021 03.
Article in English | MEDLINE | ID: covidwho-2157685
2.
Sensors (Basel) ; 22(22)2022 Nov 08.
Article in English | MEDLINE | ID: covidwho-2110219

ABSTRACT

Airborne diseases cause high mortality and adverse socioeconomic consequences. Due to urbanization, more people spend more time indoors. According to recent research, air ventilation reduces long-range airborne transmission in indoor settings. However, air ventilation solutions often incur significant energy costs and ecological footprints. The trade-offs between energy consumption and pandemic control indoors have not yet been thoroughly analyzed. In this work, we use advanced sensors to monitor the energy consumption and pandemic control capabilities of an air-conditioning system, a pedestal fan, and an open window in hospital rooms, classrooms, and conference rooms. A simulation of an indoor airborne pandemic spread of Coronavirus (COVID-19) is used to analyze the Pareto front. For the three examined room types, the Pareto front consists of all three air ventilation solutions, with some ventilation configurations demonstrating significant inefficiencies. Specifically, air-conditioning is found to be efficient only at a very high energy cost and fans seem to pose a reasonable alternative. To conclude, a more informed ventilation policy can bring about a more desirable compromise between energy consumption and pandemic spread control.


Subject(s)
Air Pollution, Indoor , COVID-19 , Humans , Pandemics/prevention & control , Air Pollution, Indoor/prevention & control , COVID-19/epidemiology , COVID-19/prevention & control , Ventilation , Air Conditioning
3.
Sci Total Environ ; 838(Pt 4): 156518, 2022 Sep 10.
Article in English | MEDLINE | ID: covidwho-2116842

ABSTRACT

BACKGROUND: The literature includes many studies which individually assess the efficacy of protective measures against the spread of the SARS-CoV-2 virus. This study considers the high infection risk in public buildings and models the quality of the indoor environment, related safety measures, and their efficacy in preventing the spread of the SARS-CoV-2 virus. METHODS: Simulations are created that consider protective factors such as hand hygiene, face covering and engagement with Covid-19 vaccination programs in reducing the risk of infection in a university foyer. Furthermore, a computational fluid dynamics model is developed to simulate and analyse the university foyer under three ventilation regimes. The probability of transmission was measured across different scenarios. FINDINGS: Estimates suggest that the Delta variant requires the air change rate to be increased >1000 times compared to the original strain, which is practically not feasible. Consequently, appropriate hygiene practices, such as wearing masks, are essential to reducing secondary infections. A comparison of different protective factors in simulations found the overall burden of infections resulting from indoor contact depends on (i) face mask adherence, (ii) quality of the ventilation system, and (iii) other hygiene practices. INTERPRETATION: Relying on ventilation, whether natural, mechanical, or mixed, is not sufficient alone to mitigate the risk of aerosol infections. This is due to the internal configuration of the indoor space in terms of (i) size and number of windows, their location and opening frequency, as well as the position of the air extraction and supply inlets, which often induce hotspots with stagnating air, (ii) the excessive required air change rate. Hence, strict reliance on proper hygiene practices, namely adherence to face coverings and hand sanitising, are essential. Consequently, face mask adherence should be emphasized and promoted by policymakers for public health applications. Similar research may need to be conducted using a similar approach on the Omicron (B.1.1.529) variant.


Subject(s)
Air Pollution, Indoor , COVID-19 , Air Pollution, Indoor/prevention & control , COVID-19/epidemiology , COVID-19/prevention & control , COVID-19 Vaccines , Humans , SARS-CoV-2 , Ventilation
4.
Int J Environ Res Public Health ; 19(21)2022 Nov 06.
Article in English | MEDLINE | ID: covidwho-2099555

ABSTRACT

The COVID-19 pandemic has generated a renewed interest in indoor air quality to limit viral spread. In the case of educational spaces, due to the high concentration of people and the fact that most of the existing buildings do not have any mechanical ventilation system, the different administrations have established natural ventilation protocols to guarantee an air quality that reduces risk of contagion by the SARS-CoV-2 virus after the return to the classrooms. Many of the initial protocols established a ventilation pattern that opted for continuous or intermittent ventilation to varying degrees of intensity. This study, carried out on a university campus in Spain, analyses the performance of natural ventilation activated through the information provided by monitoring and visualisation of real-time data. In order to carry out this analysis, a experiment was set up where a preliminary study of ventilation without providing information to the users was carried out, which was then compared with the result of providing live feedback to the occupants of two classrooms and an administration office in different periods of 2020, 2021 and 2022. In the administration office, a CO2-concentration-based method was applied retrospectively to assess the risk of airborne infection. This experience has served as a basis to establish a route for user-informed improvement of air quality in educational spaces in general through low-cost systems that allow a rational use of natural ventilation while helping maintain an adequate compromise between IAQ, comfort and energy consumption, without having to resort to mechanical ventilation systems.


Subject(s)
Air Pollution, Indoor , COVID-19 , Humans , COVID-19/epidemiology , Spain/epidemiology , Pandemics , Retrospective Studies , SARS-CoV-2 , Ventilation/methods , Air Pollution, Indoor/analysis
5.
Int J Environ Res Public Health ; 19(21)2022 Nov 05.
Article in English | MEDLINE | ID: covidwho-2099549

ABSTRACT

The supply of fresh air for underground rail transit systems is not as simple as opening windows, which is a conventional ventilation (CV) measure adopted in aboveground vehicles. This study aims to improve contaminant dilution and air purification in subway car ventilation systems and the safety of rail transit post-coronavirus disease pandemic era. We designed an air conditioning (AC) terminal system combined with stratum ventilation (SV) to enable energy consumption reduction for subway cars. We experimentally tested the effectiveness of a turbulence model to investigate ventilation in subway cars. Further, we compared the velocity fields of CV and SV in subway cars to understand the differences in their airflow organizations and contaminant removal efficiencies, along with the energy savings of four ventilation scenarios, based on the calculations carried out using computational fluid dynamics. At a ventilation flow rate of 7200 m3/h, the CO2 concentration and temperature in the breathing areas of seated passengers were better in the SV than in the CV at a rate of 8500 m3/h. Additionally, the energy-saving rate of SV with AC cooling was 14.05%. The study provides new ideas for reducing the energy consumption of rail transit and broadens indoor application scenarios of SV technology.


Subject(s)
Air Pollutants , Air Pollution, Indoor , Railroads , Automobiles , Air Pollution, Indoor/prevention & control , Air Pollution, Indoor/analysis , Air Pollutants/analysis , Environmental Monitoring , Ventilation
7.
Sci Rep ; 12(1): 17642, 2022 Oct 21.
Article in English | MEDLINE | ID: covidwho-2087309

ABSTRACT

A coronavirus disease 2019 (COVID-19) cluster emerged in a manufacturing factory in early August 2021. In November 2021, we conducted a ventilation survey using the tracer gas method. Firstly, we reproduce the situation at the time of cluster emergence and examined whether the ventilation in the office was in a condition that increased the risk of aerosol transmission. Secondly, we verified the effectiveness of the factory's own countermeasure implemented immediately after the August cluster outbreak. Furthermore, we verified the effectiveness of several additional improvement measures on the factory's own countermeasures already installed in August. Under the conditions of the cluster emergence, the air changes per hour (ACH) value was 0.73 ACH on average. The ACH value was less than 2 ACH recommended by the Ministry of Health, Labour, and Welfare, suggesting an increased risk of aerosol transmission. The factory's own countermeasures taken immediately in August were found to be effective, as the ACH value increased to 3.41 ACH on average. Moreover, it was confirmed that additional improvement measures on the factory's own countermeasures increased the ACH value to 8.33 ACH on average. In order to prevent the re-emergence of COVID-19 clusters due to aerosol infection in the office, it was found that while continuing the factory's own countermeasure, additional improvement measures should also be added depending on the number of workers in the room. In a company, it is important that workers themselves continue to take infection control measures autonomously, and confirming the effectiveness of the measures will help maintain workers' motivation. We believe it is helpful that external researchers in multiple fields and internal personnel in charge of the health and safety department and occupational health work together to confirm the effectiveness of conducted measures, such as in this case.


Subject(s)
COVID-19 , Humans , COVID-19/epidemiology , COVID-19/prevention & control , Japan/epidemiology , Respiratory Aerosols and Droplets , Ventilation , Manufacturing and Industrial Facilities
8.
Int J Environ Res Public Health ; 19(18)2022 Sep 08.
Article in English | MEDLINE | ID: covidwho-2047304

ABSTRACT

This study introduces a principle that unifies two experimental methods for evaluating airborne indoor virus-transmissions adapted to several ventilation measures. A first-time comparison of mechanical/natural ventilation and air purification with regard to infection risks is enabled. Effortful computational fluid dynamics demand detailed boundary conditions for accurate calculations of indoor airflows, which are often unknown. Hence, a suitable, simple and generalized experimental set up for identifying the spatial and temporal infection risk for different ventilation measures is more qualified even with unknown boundary conditions. A trace gas method is suitable for mechanical and natural ventilation with outdoor air exchange. For an accurate assessment of air purifiers based on filtration, a surrogate particle method is appropriate. The release of a controlled rate of either trace gas or particles simulates an infectious person releasing virus material. Surrounding substance concentration measurements identify the neighborhood exposure. One key aspect of the study is to prove that the requirement of concordant results of both methods is fulfilled. This is the only way to ensure that the comparison of different ventilation measures described above is reliable. Two examples (a two-person office and a classroom) show how practical both methods are and how the principle is applicable for different types and sizes of rooms.


Subject(s)
Air Filters , Air Pollution, Indoor , Aerosols , Air Pollution, Indoor/analysis , Filtration , Humans , Ventilation
9.
Int J Environ Res Public Health ; 19(21)2022 Oct 22.
Article in English | MEDLINE | ID: covidwho-2081823

ABSTRACT

Managing indoor environmental quality (IEQ) is a challenge in educational buildings in the wake of the COVID-19 pandemic. Adequate indoor air quality is essential to ensure that indoor spaces are safe for students and teachers. In fact, poor IEQ can affect academic performance and student comfort. This study proposes a framework for integrating occupants' feedback into the building information modelling (BIM) methodology to assess indoor environmental conditions (thermal, acoustic and lighting) and the individual airborne virus transmission risk during teaching activities. The information contained in the parametric 3D BIM model and the algorithmic environment of Dynamo were used to develop the framework. The IEQ evaluation is based on sensor monitoring and a daily schedule, so the results show real problems of occupants' dissatisfaction. The output of the framework shows in which range the indoor environmental variables were (optimal, acceptable and unacceptable) and the probability of infection during each lecture class (whether or not 1% is exceeded). A case study was proposed to illustrate its application and validate it. The outcomes provide key information to support the decision-making process for managing IEQ and controlling individual airborne virus transmission risks. Long-term application could provide data that support the management of ventilation strategies and protocol redesign.


Subject(s)
Air Pollution, Indoor , COVID-19 , Humans , Pandemics , COVID-19/epidemiology , Ventilation , Educational Status , Environmental Monitoring/methods
10.
Sensors (Basel) ; 22(19)2022 Oct 09.
Article in English | MEDLINE | ID: covidwho-2066358

ABSTRACT

COVID-19 is an infectious disease mainly transmitted through aerosol particles. Physical distancing can significantly reduce airborne transmission at a short range, but it is not a sufficient measure to avoid contagion. In recent months, health authorities have identified indoor spaces as possible sources of infection, mainly due to poor ventilation, making it necessary to take measures to improve indoor air quality. In this work, an accurate model for COVID-19 contagion risk estimation based on the Wells-Riley probabilistic approach for indoor environments is proposed and implemented as an Android mobile App. The implemented algorithm takes into account all relevant parameters, such as environmental conditions, age, kind of activities, and ventilation conditions, influencing the risk of contagion to provide the real-time probability of contagion with respect to the permanence time, the maximum allowed number of people for the specified area, the expected number of COVID-19 cases, and the required number of Air Changes per Hour. Alerts are provided to the user in the case of a high probability of contagion and CO2 concentration. Additionally, the app exploits a Bluetooth signal to estimate the distance to other devices, allowing the regulation of social distance between people. The results from the application of the model are provided and discussed for different scenarios, such as offices, restaurants, classrooms, and libraries, thus proving the effectiveness of the proposed tool, helping to reduce the spread of the virus still affecting the world population.


Subject(s)
Air Pollution, Indoor , COVID-19 , Air Pollution, Indoor/analysis , COVID-19/epidemiology , Carbon Dioxide , Humans , Respiratory Aerosols and Droplets , SARS-CoV-2 , Ventilation
11.
PLoS One ; 17(10): e0275654, 2022.
Article in English | MEDLINE | ID: covidwho-2065142

ABSTRACT

The aerosol route has been a pathway for transmission of many viruses. Similarly, recent evidence has determined aerosol transmission for SARS-CoV-2 to be significant. Consequently, public health officials and professionals have sought data regarding the role of Heating, Ventilation, and Air Conditioning (HVAC) features as a means to mitigate transmission of viruses, particularly coronaviruses. Using international standards, a systematic review was conducted to comprehensively identify and synthesize research examining the effect of humidity on transmission of coronaviruses and influenza. The results from 24 relevant studies showed that: increasing from mid (40-60%) to high (>60%) relative humidity (RH) for SARS-CoV-2 was associated with decreased virus survival; although SARS-CoV-2 results appear consistent, coronaviruses do not all behave the same; increasing from low (<40%) to mid RH for influenza was associated with decreased persistence, infectivity, viability, and survival, however effects of increased humidity from mid to high for influenza were not consistent; and medium, temperature, and exposure time were associated with inconsistency in results for both coronaviruses and influenza. Adapting humidity to mitigate virus transmission is complex. When controlling humidity as an HVAC feature, practitioners should take into account virus type and temperature. Future research should also consider the impact of exposure time, temperature, and medium when designing experiments, while also working towards more standardized testing procedures. Clinical trial registration: PROSPERO 2020 CRD42020193968.


Subject(s)
COVID-19 , Influenza, Human , Air Conditioning , Heating , Humans , Humidity , Respiratory Aerosols and Droplets , SARS-CoV-2 , Ventilation
12.
Int J Environ Res Public Health ; 19(19)2022 Sep 24.
Article in English | MEDLINE | ID: covidwho-2043744

ABSTRACT

This review aimed to provide an overview of the literature assessing the extent of COVID-19 transmission in the food processing sector along with the risk factors associated with COVID-19 infection/mortality rates in this setting, and the preventive measures used to reduce transmission. An electronic search was conducted using scientific databases, including Web of Science, OVID, PubMed and MedRxiv. The search strategy identified 26 papers that met the inclusion criteria. Six of these studies were based in the UK and the country with the most papers was the USA, with a total of nine papers. Findings showed some evidence of a high transmission level of SARS-CoV-2 within some areas of the food production sector. Risk factors associated with the spread included ethnicity, poor ventilation, lack of social distancing and lack of sick pay. The preventative measures included/recommended were social distancing, testing, adequate ventilation, cleaning regimes and access to PPE. Additional research focusing on the food production sector could show the potential variations in transmission and risk between each sub-sector. Future research focusing on the application of various preventative measures and their efficacy by sub-sector would be beneficial, while further qualitative research could help provide in-depth information regarding knowledge gaps.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/epidemiology , COVID-19/prevention & control , Humans , Ventilation
13.
Int J Environ Res Public Health ; 19(18)2022 Sep 06.
Article in English | MEDLINE | ID: covidwho-2010075

ABSTRACT

The COVID-19 pandemic has made significant impacts on public health, including human exposure to airborne pathogens. In healthcare facilities, the locations of return air vents in ventilation systems may have important effects on lowering airborne SARS-CoV-2 transmission. This study conducted experiments to examine the influence of different return air vents' heights (0.7 m, 1.2 m, and 1.6 m) on the particle removal effects in a simulated patient ward. Three different ventilation systems were examined: top celling air supply-side wall return (TAS), underfloor air supply-side wall return (UFAS) and side wall air supply-side wall return (SAS). CFD simulation was applied to further study the effects of return air inlets' heights (0.3 m, 0.7 m, 1.2 m, 1.6 m, and 2.0 m) and air exchange rates. The technique for order of preference by similarity to ideal solution (TOPSIS) analysis was used to calculate the comprehensive scores of 60 scenarios using a multi-criterion method to obtain the optimal return air inlets' heights. Results showed that for each additional 0.5 m distance in most working conditions, the inhalation fraction index of medical staff could be reduced by about 5-20%. However, under certain working conditions, even though the distances between the patients and medical personnel were different, the optimal heights of return air vents were constant. For TAS and UFAS, the optimal return air inlets' height was 1.2 m, while for SAS, the best working condition was 1.6 m air supply and 0.7 m air return. At the optimum return air heights, the particle decay rate per hour of SAS was 75% higher than that of TAS, and the rate of particle decay per hour of SAS was 21% higher than that of UFAS. The location of return air inlets could further affect the operating cost-effectiveness of ventilation systems: the highest operating cost-effectiveness was 8 times higher than the lowest one.


Subject(s)
Air Pollution, Indoor , COVID-19 , Air Pollution, Indoor/analysis , Air Pollution, Indoor/prevention & control , Bays , COVID-19/epidemiology , Hospitals , Humans , Pandemics , SARS-CoV-2 , Ventilation/methods
14.
Indoor Air ; 32(8): e13097, 2022 08.
Article in English | MEDLINE | ID: covidwho-2008742

ABSTRACT

In a virus pandemic context, buildings ventilation has been recognized as a solution for preventing transmission of the virus in aerosolized form. The impact of the widespread recommendation of window opening and sealing door on ventilation circuits needs to be considered with a multizone approach. We modeled the airflow distribution in a building where people are isolating in a pandemic context, including one infected person. We analyzed the impact of opening the window and sealing the door in the quarantine room on exposures and probability of infection for occupants of the flat and of adjacent flats. In order to study the sensitivity of the results, we tested three ventilation systems: balanced, exhaust-only, and humidity-based demand-controlled, and several window- and door-opening strategies. When the door of the quarantine room is sealed, we observe that opening the window in the quarantine room always results in increased exposure and probability of infection for at least one other occupant, including in neighbors' apartments. When all internal doors are opened, we observe moderate impacts, with rather an increase of exposure of the occupants of the same apartments and of their probability of infection, and a decrease for the occupants located in other apartments. Based on the analysis on the airflows distribution in this case study, we conclude that sealing the internal door has more influence than opening the window of the quarantine room, whatever the ventilation system. We observe that this widespread recommendation to open the window of a quarantine room and to seal the door is based on the consideration of a single zone model. We illustrate the importance of moving from such a single zone approach to a multizone approach for quantifying ventilation and airing impacts in multizone buildings as residences in order to prevent epidemics of viruses such as SARS-CoV-2. It highlights the need of air leakage databases.


Subject(s)
Air Pollution, Indoor , COVID-19 , Housing , Humans , SARS-CoV-2 , Ventilation/methods
15.
Indoor Air ; 32(8): e13087, 2022 08.
Article in English | MEDLINE | ID: covidwho-2008741

ABSTRACT

The SARS-CoV-2 pandemic, which suddenly appeared at the beginning of 2020, revealed our knowledge deficits in terms of ventilation and air pollution control. It took many weeks to realize that aerosols are the main route of transmission. The initial attempt to hold back these aerosols through textile masks seemed almost helpless, although there is sufficient knowledge about the retention capacity of fabric filters for aerosols. In the absence of a sufficient number of permanently installed heating, ventilation, and air conditioning systems, three main approaches are pursued: (a) increasing the air exchange rate by supplying fresh air, (b) using mobile air purifiers, and (c) disinfection by introducing active substances into the room air. This article discusses the feasibility of these different approaches critically. It also provides experimental results of air exchange measurements in a school classroom that is equipped with a built-in fan for supplying fresh air. With such a fan and a window tilted at the appropriate distance, an air exchange rate of 5/h can be set at a low power level and without any significant noise pollution. Heat balance calculations show that no additional heat exchanger is necessary in a normal classroom with outside temperatures above 10°C. Furthermore, a commercial mobile air purifier is studied in a chamber and a test room setup in order to examine and evaluate the efficiency of such devices against viable viruses under controlled and realistic conditions. For this purpose, bacteriophages of the type MS2 are used. Both window ventilation and air purifiers were found to be suitable to reduce the concentration of phages in the room.


Subject(s)
Air Pollution, Indoor , COVID-19 , Air Pollution, Indoor/prevention & control , COVID-19/prevention & control , Humans , Respiratory Aerosols and Droplets , SARS-CoV-2 , Schools , Ventilation/methods
16.
Anaesthesia ; 77(10): 1097-1105, 2022 10.
Article in English | MEDLINE | ID: covidwho-2008732

ABSTRACT

The ability to measure and track aerosols in the vicinity of patients with suspected or confirmed COVID-19 is highly desirable. At present, there is no way to measure and track, in real time, the sizes, dispersion and dilution/disappearance of aerosols that are generated by airway manipulations such as mask ventilation; tracheal intubation; bronchoscopy; dental and gastro-intestinal endoscopy procedures; or by vigorous breathing, coughing or exercise. We deployed low-cost photoelectric sensors in five operating theatres between surgical cases. We measured and analysed dilution and exfiltration of aerosols we generated to evaluate air handling and dispersion under real-world conditions. These data were used to develop a model of aerosol persistence. We found significant variation between different operating theatres. Equipment placement near air vents affects air flows, impacting aerosol movement and elimination patterns. Despite these impediments, air exchange in operating theatres is robust and prolonged fallow time before theatre turnover may not be necessary. Significant concentrations of aerosols are not seen in adjoining areas outside of the operating theatre. These models and dispersion rates can predict aerosol persistence in operating theatres and other clinical areas and potentially facilitate quantification of risk, with obvious and far-reaching implications for designing, evaluating and confirming air handling in non-medical environments.


Subject(s)
COVID-19 , Cough , Humans , Operating Rooms , Respiratory Aerosols and Droplets , Ventilation
17.
Indoor Air ; 32(8): e13099, 2022 08.
Article in English | MEDLINE | ID: covidwho-2005271

ABSTRACT

Particle size removal efficiencies for 0.1-1.0 µm ( PSE 0.1 - 1.0 $$ {PSE}_{0.1-1.0} $$ ) and 0.3-1.0 µm ( PSE 0.3 - 1.0 $$ {PSE}_{0.3-1.0} $$ ) diameter of Minimum Efficiency Reporting Value (MERV) filters, an electrostatic enhanced air filter (EEAF), and their two-stage filtration systems were evaluated. Considering the most penetrating particle size was 0.1-0.4 µm particulate matter (PM), the PSE 0.1 - 1.0 $$ {PSE}_{0.1-1.0} $$ as an evaluation parameter deserves more attention during the COVID-19 pandemic, compared to the PSE 0.3 - 1.0 $$ {PSE}_{0.3-1.0} $$ . The MERV 13 filters were recommended for a single-stage filtration system because of their superior quality factor (QF) compared to MERV 6, MERV 8, MERV 11 filters, and the EEAF. Combined MERV 8 + MERV 11 filters have the highest QF compared to MERV 6 + MERV 11 filters and EEAF + MERV 11 filters; regarding 50% of PSE 0.1 - 1.0 $$ {PSE}_{0.1-1.0} $$ as the filtration requirements of two-stage filtration systems, the MERV 8 + MERV 11 filtration system can achieve this value at 1.0 m/s air velocity, while PSE 0.1 - 1.0 $$ {PSE}_{0.1-1.0} $$ values were lower than 50% at 1.5 m/s and 2.0 m/s. EEAF obtained a better PSE 0.3 - 1.0 $$ {PSE}_{0.3-1.0} $$ in the full-recirculated test rig than in the single-pass mode owing to active ionization effects when EEAF was charged by alternating current.


Subject(s)
Air Filters , Air Pollution, Indoor , COVID-19 , Air Conditioning , Air Pollution, Indoor/analysis , Filtration , Heating , Humans , Pandemics , Respiration , Ventilation
18.
Indoor Air ; 32(8): e13094, 2022 08.
Article in English | MEDLINE | ID: covidwho-2005270

ABSTRACT

As virus-laden aerosols can accumulate and remain suspended for hours in insufficiently ventilated enclosed spaces, indoor environments can heavily contribute to the spreading of airborne infections. In the COVID-19 pandemics, the role possibly played by cable cars has attracted media attention following several outbreaks in ski resort. To assess the real risk of infection, we experimentally characterize the natural ventilation in cable cars and develop a general stochastic model of infection in an arbitrary indoor space that accounts for the epidemiological situation, the virological parameters, and the indoor characteristics (ventilation rate and occupant number density). As a results of the high air exchange rate (we measured up to 180 air changes per hour) and the relatively short duration of the journey, the infection probability in cable cars traveling with open windows is remarkably lower than in other enclosed spaces such as aircraft cabins, train cars, offices, classrooms, and dining rooms. Accounting for the typical duration of the stay, the probability of infection during a cable-car ride is lower by two to three orders of magnitude than in the other examples considered (the highest risk being estimated in case of a private gathering in a poorly ventilated room). For most practical purposes, the infection probability can be approximated by the inhaled viral dose, which provides an upper bound and allows a simple comparison between different indoor situations once the air exchange rate and the occupant number density are known. Our approach and findings are applicable to any indoor space in which the viral transmission is predominately airborne and the air is well mixed.


Subject(s)
Air Pollution, Indoor , COVID-19 , Automobiles , COVID-19/epidemiology , Humans , Respiratory Aerosols and Droplets , Ventilation
19.
J Hazard Mater ; 439: 129697, 2022 10 05.
Article in English | MEDLINE | ID: covidwho-1966844

ABSTRACT

Converging evidence reports that the probability of vertical transmission patterns via shared drainage systems, may be responsible for the huge contactless community outbreak in high-rise buildings. Publications indicate that a faulty bathroom exhaust fan system is ineffective in removing lifted hazardous virus-laden aerosols from the toilet bowl space. Common strategies (boosting ventilation capability and applying disinfection tablets) seem unsustainable and remain to date untested. Using combined simulation and experimental approaches, we compared three ventilation schemes in a family bathroom including the traditional ceiling fan, floor fan, and side-wall fan. We found that the traditional ceiling fan was barely functional whereby aerosol particles were not being adequately removed. Conversely, a side-wall fan could function efficiently and an enhanced ventilation capability can have increased performance whereby nearly 80.9% of the lifted aerosol particles were removed. There exists a common, and easily-overlooked mistake in the layout of the bathroom, exposing occupants to a contactless vertical pathogen aerosol transmission route. Corrections and dissemination are thus imperative for the reconstruction of these types of family bathrooms. Our findings provide evidence for the bathroom and smart ventilation system upgrade, promoting indoor public health and human hygiene.


Subject(s)
COVID-19 , Toilet Facilities , COVID-19/prevention & control , Computer Simulation , Humans , Respiratory Aerosols and Droplets , Ventilation
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