Quantifying the Impact of Ultraviolet Subtype C in Reducing Airborne Pathogen Transmission and Improving Energy Efficiency in Healthy Buildings: A Kahn–Mariita Equivalent Ventilation Model

There is growing evidence that viruses responsible for pandemics, such as Middle East respiratory syndrome and severe acute respiratory syndrome, are mainly spread through aerosols. Recommendations have been introduced to reduce the transmission risks of virulent airborne viral particles by increasing ventilation rates, expressed in air changes per hour (ACHs), effectively improving the dilution of pathogens via mechanical ventilation. However, infrastructural and operational costs associated with upgrades of building heating, ventilation, and air conditioning systems make these solutions expensive. It is well documented that Ultraviolet Subtype C (UVC) disinfection can help lower exposure risks by inactivating viruses and the performance of such solutions can translate into equivalent ventilation. Here, we present the first framework to extract the optimal UVC requirements to improve facility management yet ensuring compliance with ventilation guidelines at lower energy costs. The Kahn–Mariita (KM) model considers the air quality of shared enclosed spaces over time by supplementing the existing mechanical ventilation with localized UVC air treatment and includes variables such as room size, occupancy, existing ventilation, and target equivalent ACH. For example, the model applied to a conference room shows that a UVC chamber with recirculation rates of 160 m3/h increases ventilation from an ACH 3 to 7.9 and reduces the room’s reset time from 46 to <10 min with as little as 1 W. Recirculation rates of 30 m3/h however offer no benefits beyond 200 mW, with an eACH of 3.9 and reset time of 31 min. The first finding is that single-pass disinfection is not an appropriate metric of performance, i.e., low recirculation rates increase single-pass disinfection, and, however, only treats a portion of the space volume within a given time, limiting the overall performance. Conversely, higher recirculation rates decrease single-pass disinfection but treat larger portions of air, potentially multiple times, and are therefore expected to lower the transmission risk faster. The second result is that for fixed amounts of recirculating air flow, increasing UVC power helps with diminishing return, while for a fixed UVC power, increasing the recirculating air flow will always help. This dynamic is particularly important toward optimizing solutions, given the constraints system engineers must work with, and particularly to design for end-user benefits such as increased occupancy, in-dwelling time, or reduction of shared-space reset time.

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An analytical study to evaluate the impact of distributed zone fans on the air flow rate in a mechanical ventilation system

Building Services Engineering Research and Technology ◽

10.1177/0143624419873761 ◽

2019 ◽

Vol 41 (4) ◽

pp. 507-516

Author(s):

Fa-Li Ju ◽

Liying Liu ◽

Xiaoping Yu

Keyword(s):

Mechanical Ventilation ◽

Flow Rate ◽

Pressure Ratio ◽

Air Flow ◽

Ventilation System ◽

Theoretical Expression ◽

Air Flow Rate ◽

Rate Testing ◽

Fan Speed ◽

The Impact

Based on air flow rate testing of each branch fan in a distributed fan ventilation system under different branch air duct inlet static pressures, the conclusion can be drawn that there is a branch fan air flow rate deviation phenomenon. The air flow rate of the branch fan increases with the branch air duct inlet static pressure at the same branch fan speed, and the branch fan hinders the air flow rate in some cases. In this study, a theoretical expression of the deviation of the branch air duct design air flow rate was established, and the influencing factors of the deviation were determined to include the branch air duct resistance characteristics, branch fan performance, and branch air duct inlet pressure ratio. A graphic analytical method for determining the deviation of the branch fan design air flow rate was also proposed. Both methods can provide a theoretical basis for calculating and analysing the deviation of the branch fan design air flow rate in a distributed fan ventilation system. Practical application: This paper provides new data on the performance of a distributed fan ventilation system. Our results could be used to evaluate the impact of distributed zone fans on the air flow rate in a mechanical ventilation system. Crucially, we not only propose two types of methods that can be applied to predict deviations of the air flow rate in a distributed fan ventilation system caused by the branch air duct inlet static pressures but also obtain the factors that are important for understanding the true impact of the deviation of the branch fan air flow rate. This study lays an important foundation for the design and operation of building mechanical ventilation systems.

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Model of thermal buoyancy in cavity-ventilated roof constructions

Journal of Building Physics ◽

10.1177/1744259120984189 ◽

2021 ◽

pp. 174425912098418

Author(s):

Toivo Säwén ◽

Martina Stockhaus ◽

Carl-Eric Hagentoft ◽

Nora Schjøth Bunkholt ◽

Paula Wahlgren

Keyword(s):

Analytical Model ◽

Flow Rate ◽

Numerical Study ◽

Air Flow ◽

Wind Pressure ◽

Air Flow Rate ◽

Test Set ◽

Air Cavity ◽

Thermal Buoyancy ◽

The Impact

Timber roof constructions are commonly ventilated through an air cavity beneath the roof sheathing in order to remove heat and moisture from the construction. The driving forces for this ventilation are wind pressure and thermal buoyancy. The wind driven ventilation has been studied extensively, while models for predicting buoyant flow are less developed. In the present study, a novel analytical model is presented to predict the air flow caused by thermal buoyancy in a ventilated roof construction. The model provides means to calculate the cavity Rayleigh number for the roof construction, which is then correlated with the air flow rate. The model predictions are compared to the results of an experimental and a numerical study examining the effect of different cavity designs and inclinations on the air flow rate in a ventilated roof subjected to varying heat loads. Over 80 different test set-ups, the analytical model was found to replicate both experimental and numerical results within an acceptable margin. The effect of an increased total roof height, air cavity height and solar heat load for a given construction is an increased air flow rate through the air cavity. On average, the analytical model predicts a 3% higher air flow rate than found in the numerical study, and a 20% lower air flow rate than found in the experimental study, for comparable test set-ups. The model provided can be used to predict the air flow rate in cavities of varying design, and to quantify the impact of suggested roof design changes. The result can be used as a basis for estimating the moisture safety of a roof construction.

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Metagenomics Analysis Reveals the Microbial Communities, Antimicrobial Resistance Gene Diversity and Potential Pathogen Transmission Risk of Two Different Landfills in China

Diversity ◽

10.3390/d13060230 ◽

2021 ◽

Vol 13 (6) ◽

pp. 230

Author(s):

Shan Wan ◽

Min Xia ◽

Jie Tao ◽

Yanjun Pang ◽

Fugen Yu ◽

...

Keyword(s):

Antibiotic Resistance ◽

Microbial Communities ◽

Resistance Gene ◽

Resistance Genes ◽

Gene Diversity ◽

Antibiotic Resistance Gene ◽

Antibiotic Resistance Genes ◽

Pathogen Transmission ◽

Transmission Risk ◽

Antimicrobial Resistance Gene

In this study, we used a metagenomic approach to analyze microbial communities, antibiotic resistance gene diversity, and human pathogenic bacterium composition in two typical landfills in China. Results showed that the phyla Proteobacteria, Bacteroidetes, and Actinobacteria were predominant in the two landfills, and archaea and fungi were also detected. The genera Methanoculleus, Lysobacter, and Pseudomonas were predominantly present in all samples. sul2, sul1, tetX, and adeF were the four most abundant antibiotic resistance genes. Sixty-nine bacterial pathogens were identified from the two landfills, with Klebsiella pneumoniae, Bordetella pertussis, Pseudomonas aeruginosa, and Bacillus cereus as the major pathogenic microorganisms, indicating the existence of potential environmental risk in landfills. In addition, KEGG pathway analysis indicated the presence of antibiotic resistance genes typically associated with human antibiotic resistance bacterial strains. These results provide insights into the risk of pathogens in landfills, which is important for controlling the potential secondary transmission of pathogens and reducing workers’ health risk during landfill excavation.

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Lower peripheral blood Toll-like receptor 3 expression is associated with an unfavorable outcome in severe COVID-19 patients

Scientific Reports ◽

10.1038/s41598-021-94624-4 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Maria Clara Saad Menezes ◽

Alicia Dudy Müller Veiga ◽

Thais Martins de Lima ◽

Suely Kunimi Kubo Ariga ◽

Hermes Vieira Barbeiro ◽

...

Keyword(s):

Mechanical Ventilation ◽

Peripheral Blood ◽

World Health ◽

Control Group ◽

Pyrin Domain ◽

Peripheral Blood Gene Expression ◽

Severe Group ◽

Health Organization ◽

The Impact

AbstractThe role of innate immunity in COVID-19 is not completely understood. Therefore, this study explored the impact of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection on the expression of Pattern Recognition Receptors (PRRs) in peripheral blood cells and their correlated cytokines. Seventy-nine patients with severe COVID-19 on admission, according to World Health Organization (WHO) classification, were divided into two groups: patients who needed mechanical ventilation and/or deceased (SEVERE, n = 50) and patients who used supplementary oxygen but not mechanical ventilation and survived (MILD, n = 29); a control group (CONTROL, n = 17) was also enrolled. In the peripheral blood, gene expression (mRNA) of Toll-like receptors (TLRs) 3, 4, 7, 8, and 9, retinoic-acid inducible gene I (RIGI), NOD-like receptor family pyrin domain containing 3 (NLRP3), interferon alpha (IFN-α), interferon beta (IFN-β), interferon gamma (IFN-γ), interferon lambda (IFN-λ), pro-interleukin(IL)-1β (pro-IL-1β), and IL-18 was determined on admission, between 5–9 days, and between 10–15 days. Circulating cytokines in plasma were also measured. When compared to the COVID-19 MILD group, the COVID-19 SEVERE group had lower expression of TLR3 and overexpression of TLR4.

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Virus Transmission Risk in Urban Rail Systems: Microscopic Simulation-Based Analysis of Spatio-Temporal Characteristics

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/03611981211010181 ◽

2021 ◽

pp. 036119812110101

Author(s):

Jiali Zhou ◽

Haris N. Koutsopoulos

Keyword(s):

Public Transportation ◽

Virus Transmission ◽

Flow Characteristics ◽

Transportation Systems ◽

Transmission Risk ◽

Microscopic Simulation ◽

Spatial And Temporal Patterns ◽

Subway System ◽

Public Transportation Systems ◽

The Impact

The transmission risk of airborne diseases in public transportation systems is a concern. This paper proposes a modified Wells-Riley model for risk analysis in public transportation systems to capture the passenger flow characteristics, including spatial and temporal patterns, in the number of boarding and alighting passengers, and in number of infectors. The model is used to assess overall risk as a function of origin–destination flows, actual operations, and factors such as mask-wearing and ventilation. The model is integrated with a microscopic simulation model of subway operations (SimMETRO). Using actual data from a subway system, a case study explores the impact of different factors on transmission risk, including mask-wearing, ventilation rates, infectiousness levels of disease, and carrier rates. In general, mask-wearing and ventilation are effective under various demand levels, infectiousness levels, and carrier rates. Mask-wearing is more effective in mitigating risks. Impacts from operations and service frequency are also evaluated, emphasizing the importance of maintaining reliable, frequent operations in lowering transmission risks. Risk spatial patterns are also explored, highlighting locations of higher risk.

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936. Evaluating the Impact of Polypharmacy on Virologic Success in People with HIV

Open Forum Infectious Diseases ◽

10.1093/ofid/ofaa439.1122 ◽

2020 ◽

Vol 7 (Supplement_1) ◽

pp. S501-S502

Author(s):

Humberto R Jimenez ◽

Naana Boachie ◽

Sangwon Park ◽

Jin Suh

Keyword(s):

Hiv Transmission ◽

Virologic Failure ◽

Descriptive Analysis ◽

Virologic Response ◽

Transmission Risk ◽

Pill Burden ◽

Cross Sectional ◽

Hiv Rna ◽

Aids Diagnosis ◽

The Impact

Abstract Background As people with HIV (PWH) have experienced reductions in antiretroviral pill burden, there has been an increase in medications to manage non-AIDS-related co-morbidities. Previous studies have linked virologic failure to an increased pill burden. This study assessed whether polypharmacy and other variables affect success of HIV management in our population. Methods A retrospective, cross-sectional analysis of PWH receiving care at a Ryan White-funded clinic in New Jersey was performed. Eligible patients were ≥18 years old, had ≥2 visits in 2019 and were receiving antiretroviral therapy (ART). The primary endpoints were to determine the effect polypharmacy (defined as 5 or more non-ART pills per day) on virologic response rates (HIV RNA < 200 copies/mL). Secondary endpoints accounted for the impact of age, gender, race/ethnicity, HIV transmission risk factor, and AIDS diagnosis on virologic response. A descriptive analysis of comorbidities and medication classes was also completed. Logistic regression, chi square and student’s t test were used for statistical analysis. Results 964 patients were included in the analysis, with 355 (37%) meeting the criteria for polypharmacy. Most patients were male (60%) and the mean age was 49 years of age. The racial/ethnic breakdown was 46% Hispanic, 45% Black and 8% White. Polypharmacy was associated with higher rates of virologic success compared to those with a lower pill burden: 94% vs 86% had an HIV RNA < 200 copies/mL (P=0.0003), respectively. ART pill burden was statistically, but not clinically higher among those with polypharmacy (1.34 vs 1.45, P=0.025). Virologic response was found to be higher among Hispanics and Whites in comparison to Black patients (OR 2.2, CI 1.4-3.5 and 3.0, CI 1.1-8.2). Patients with an AIDS diagnosis were less likely to achieve virologic response (OR 0.64, CI 0.42-0.99). Conclusion Patients with polypharmacy were more likely to achieve virologic success than paitents with a low pill burden in our population. Disclosures Humberto R. Jimenez, PharmD, BCPS, AAHIVP, Gilead (Speaker’s Bureau)

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375. COVID 19 infection in a Massachusetts community hospital

Open Forum Infectious Diseases ◽

10.1093/ofid/ofaa439.570 ◽

2020 ◽

Vol 7 (Supplement_1) ◽

pp. S257-S258

Author(s):

Raul Davaro ◽

alwyn rapose

Keyword(s):

Intensive Care Unit ◽

Mechanical Ventilation ◽

Intensive Care ◽

Essential Hypertension ◽

Severe Acute Respiratory Syndrome ◽

High Mortality ◽

Case Series ◽

World Health ◽

Minimal Risk ◽

The Impact

Abstract Background The ongoing pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections has led to 105690 cases and 7647 deaths in Massachusetts as of June 16. Methods The study was conducted at Saint Vincent Hospital, an academic health medical center in Worcester, Massachusetts. The institutional review board approved this case series as minimal-risk research using data collected for routine clinical practice and waived the requirement for informed consent. All consecutive patients who were sufficiently medically ill to require hospital admission with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection by positive result on polymerase chain reaction testing of a nasopharyngeal sample were included. Results A total of 109 consecutive patients with COVID 19 were admitted between March 15 and May 31. Sixty one percent were men, the mean age of the cohort was 67. Forty one patients (37%) were transferred from nursing homes. Twenty seven patients died (24%) and the majority of the dead patients were men (62%). Fifty one patients (46%) required admission to the medical intensive care unit and 34 necessitated mechanical ventilation, twenty two patients on mechanical ventilation died (63%). The most common co-morbidities were essential hypertension (65%), obesity (60%), diabetes (33%), chronic kidney disease (22%), morbid obesity (11%), congestive heart failure (16%) and COPD (14%). Five patients required hemodialysis. Fifty five patients received hydroxychloroquine, 24 received tocilizumab, 20 received convalescent plasma and 16 received remdesivir. COVID 19 appeared in China in late 2019 and was declared a pandemic by the World Health Organization on March 11, 2020. Our study showed a high mortality in patients requiring mechanical ventilation (43%) as opposed to those who did not (5.7%). Hypertension, diabetes and obesity were highly prevalent in this aging population. Our cohort was too small to explore the impact of treatment with remdesivir, tocilizumab or convalescent plasma. Conclusion In this cohort obesity, diabetes and essential hypertension are risk factors associated with high mortality. Patients admitted to the intensive care unit who need mechanical ventilation have a mortality approaching 50 %. Disclosures All Authors: No reported disclosures

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The Impact of Intervention-Related Risk Factors on the Risk of Ventilator-Associated Pneumonia Is High in a Neurosurgical Intensive Care Unit

Infection Control and Hospital Epidemiology ◽

10.1017/ice.2020.1059 ◽

2020 ◽

Vol 41 (S1) ◽

pp. s407-s409

Author(s):

Ksenia Ershova ◽

Oleg Khomenko ◽

Olga Ershova ◽

Ivan Savin ◽

Natalia Kurdumova ◽

...

Keyword(s):

Risk Factors ◽

Mechanical Ventilation ◽

Negative Slope ◽

Infection Prevention And Control ◽

Ventilator Associated Pneumonia ◽

Related Factors ◽

Icu Patients ◽

The Impact ◽

Adf Test ◽

Over Time

Background: Ventilator-associated pneumonia (VAP) represents the highest burden among all healthcare-associated infections (HAIs), with a particularly high rate in patients in neurosurgical ICUs. Numerous VAP risk factors have been identified to provide a basis for preventive measures. However, the impact of individual factors on the risk of VAP is unclear. The goal of this study was to evaluate the dynamics of various VAP risk factors given the continuously declining prevalence of VAP in our neurosurgical ICU. Methods: This prospective cohort unit-based study included neurosurgical patients who stayed in the ICU >48 consecutive hours in 2011 through 2018. The infection prevention and control (IPC) program was implemented in 2010 and underwent changes to adopt best practices over time. We used a 2008 CDC definition for VAP. The dynamics of VAP risk factors was considered a time series and was checked for stationarity using theAugmented Dickey-Fuller test (ADF) test. The data were censored when a risk factor was present during and after VAP episodes. Results: In total, 2,957 ICU patients were included in the study, 476 of whom had VAP. Average annual prevalence of VAP decreased from 15.8 per 100 ICU patients in 2011 to 9.5 per 100 ICU patients in 2018 (Welch t test P value = 7.7e-16). The fitted linear model showed negative slope (Fig. 1). During a study period we observed substantial changes in some risk factors and no changes in others. Namely, we detected a decrease in the use of anxiolytics and antibiotics, decreased days on mechanical ventilation, and a lower rate of intestinal dysfunction, all of which were nonstationary processes with a declining trend (ADF testP > .05) (Fig. 2). However, there were no changes over time in such factors as average age, comorbidity index, level of consciousness, gender, and proportion of patients with brain trauma (Fig. 2). Conclusions: Our evidence-based IPC program was effective in lowering the prevalence of VAP and demonstrated which individual measures contributed to this improvement. By following the dynamics of known VAP risk factors over time, we found that their association with declining VAP prevalence varies significantly. Intervention-related factors (ie, use of antibiotics, anxiolytics and mechanical ventilation, and a rate of intestinal dysfunction) demonstrated significant reduction, and patient-related factors (ie, age, sex, comorbidity, etc) remained unchanged. Thus, according to the discriminative model, the intervention-related factors contributed more to the overall risk of VAP than did patient-related factors, and their reduction was associated with a decrease in VAP prevalence in our neurosurgical ICU.Funding: NoneDisclosures: None

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Quantity and Quality of Aquaculture Enrichments Influence Disease Epidemics and Provide Ecological Alternatives to Antibiotics

Antibiotics ◽

10.3390/antibiotics10030335 ◽

2021 ◽

Vol 10 (3) ◽

pp. 335

Author(s):

Anssi Karvonen ◽

Ville Räihä ◽

Ines Klemme ◽

Roghaieh Ashrafi ◽

Pekka Hyvärinen ◽

...

Keyword(s):

Disease Transmission ◽

Bacterial Infections ◽

Environmental Heterogeneity ◽

Pathogen Transmission ◽

Central Component ◽

Flavobacterium Columnare ◽

Disease Epidemics ◽

The Impact ◽

Environmental Microbes

Environmental heterogeneity is a central component influencing the virulence and epidemiology of infectious diseases. The number and distribution of susceptible hosts determines disease transmission opportunities, shifting the epidemiological threshold between the spread and fadeout of a disease. Similarly, the presence and diversity of other hosts, pathogens and environmental microbes, may inhibit or accelerate an epidemic. This has important applied implications in farming environments, where high numbers of susceptible hosts are maintained in conditions of minimal environmental heterogeneity. We investigated how the quantity and quality of aquaculture enrichments (few vs. many stones; clean stones vs. stones conditioned in lake water) influenced the severity of infection of a pathogenic bacterium, Flavobacterium columnare, in salmonid fishes. We found that the conditioning of the stones significantly increased host survival in rearing tanks with few stones. A similar effect of increased host survival was also observed with a higher number of unconditioned stones. These results suggest that a simple increase in the heterogeneity of aquaculture environment can significantly reduce the impact of diseases, most likely operating through a reduction in pathogen transmission (stone quantity) and the formation of beneficial microbial communities (stone quality). This supports enriched rearing as an ecological and economic way to prevent bacterial infections with the minimal use of antimicrobials.

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Impact of an accelerated melting of Greenland on malaria distribution over Africa

Nature Communications ◽

10.1038/s41467-021-24134-4 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Alizée Chemison ◽

Gilles Ramstein ◽

Adrian M. Tompkins ◽

Dimitri Defrance ◽

Guigone Camus ◽

...

Keyword(s):

Climate Change ◽

Malaria Transmission ◽

Ice Sheet ◽

Transmission Risk ◽

Future Climate Change ◽

Climate Change Scenarios ◽

Climate Change Risk ◽

System A ◽

Climate Simulations ◽

The Impact

AbstractStudies about the impact of future climate change on diseases have mostly focused on standard Representative Concentration Pathway climate change scenarios. These scenarios do not account for the non-linear dynamics of the climate system. A rapid ice-sheet melting could occur, impacting climate and consequently societies. Here, we investigate the additional impact of a rapid ice-sheet melting of Greenland on climate and malaria transmission in Africa using several malaria models driven by Institute Pierre Simon Laplace climate simulations. Results reveal that our melting scenario could moderate the simulated increase in malaria risk over East Africa, due to cooling and drying effects, cause a largest decrease in malaria transmission risk over West Africa and drive malaria emergence in southern Africa associated with a significant southward shift of the African rain-belt. We argue that the effect of such ice-sheet melting should be investigated further in future public health and agriculture climate change risk assessments.

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