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Introduction: Literature is lacking on the safety of storing contaminated PPE in paper bags for reuse, potentially increasing exposure to frontline healthcare workers (HCW) and patients. The aim of this study is to evaluate the effectiveness of paper bags as a barrier for fomite transmission of SARS-CoV-2 by storing face masks, respirators, and face shields. Methods: This quasi-experimental study evaluated the presence of SARS-CoV-2 on the interior and exterior surfaces of paper bags containing PPE that had aerosolized exposures in clinical and simulated settings. Between May and October 2020, 30 unique PPE items were collected from COVID-19 units at two urban hospitals. Exposed PPE, worn by either an infected patient or HCW during a SARS-CoV-2 aerosolizing event, were placed into an unused paper bag. Samples were tested at 30-minute and 12-hour intervals. Results: A total of 177 swabs were processed from 30 PPE samples. We found a 6.8% positivity rate among all samples across both collection sites. Highest positivity rates were associated with ventilator disconnection and exposure to respiratory droplets from coughing. Positivity rates differed between hospital units. Total positivity rates were similar between 30-minute (6.7%) and 12-hour (6.9%) sample testing time intervals. Control samples exposed to inactivated SARS-CoV-2 droplets had higher total viral counts than samples exposed to nebulized aerosols. Conclusions: Data suggests paper bags are not a significant fomite risk for SARS-CoV-2 transmission. However, controls demonstrated a risk with droplet exposure. Data can inform guidelines for storing and re-using PPE in situations of limited supplies during future pandemics. [ABSTRACT FROM AUTHOR]

The worldwide spread of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has ubiquitously impacted many aspects of life. As vaccines continue to be manufactured and administered, limiting the spread of SARS-CoV-2 will rely more heavily on the early identification of contagious individuals occupying reopened and increasingly populated indoor environments. In this study, we investigated the utility of an impaction-based bioaerosol sampling system with multiple nucleic acid collection media. Heat-inactivated SARS-CoV-2 was utilized to perform bench-scale, short-range aerosol, and room-scale aerosol experiments. Through bench-scale experiments, AerosolSense Capture Media (ACM) and nylon flocked swabs were identified as the highest utility media. In room-scale aerosol experiments, consistent detection of aerosol SARS-CoV-2 was achieved at an estimated aerosol concentration equal to or greater than 0.089 genome copies per liter of room air (gc/L) when air was sampled for eight hours or more at less than one air change per hour (ACH). Shorter sampling periods (75 minutes) yielded consistent detection at ~31.8 gc/L of room air and intermittent detection down to ~0.318 gc/L at (at both 1 and 6 ACH). These results support further exploration in real-world testing scenarios and suggest the utility of indoor aerosol surveillance as an effective risk mitigation strategy in occupied buildings. [ABSTRACT FROM AUTHOR]

Evidence continues to grow supporting the aerosol transmission of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). To assess the potential role of heating, ventilation, and air conditioning (HVAC) systems in airborne viral transmission, this study sought to determine the viral presence, if any, on air handling units in a healthcare setting where coronavirus disease 2019 (COVID‐19) patients were being treated. The presence of SARS‐CoV‐2 RNA was detected in approximately 25% of samples taken from ten different locations in multiple air handlers. While samples were not evaluated for viral infectivity, the presence of viral RNA in air handlers raises the possibility that viral particles can enter and travel within the air handling system of a hospital, from room return air through high‐efficiency MERV‐15 filters and into supply air ducts. Although no known transmission events were determined to be associated with these specimens, the findings suggest the potential for HVAC systems to facilitate transfer of virions to locations remote from areas where infected persons reside. These results are important within and outside of healthcare settings and may present necessary guidance for building operators of facilities that are not equipped with high‐efficiency filtration. Furthermore, the identification of SARS‐CoV‐2 in HVAC components indicates the potential utility as an indoor environmental surveillance location. [ABSTRACT FROM AUTHOR]

Previous studies demonstrate an exchange of bacteria between hospital room surfaces and patients, and a reduction in survival of microorganisms in dust inside buildings from sunlight exposure. While the transmission of microorganisms between humans and their local environment is a continuous exchange which generally does not raise cause for alarm, in a hospital setting with immunocompromised patients, these building-source microbial reservoirs may pose a risk. Window glass is often neglected during hospital disinfection protocols, and the microbial communities found there have not previously been examined. This pilot study examined whether living bacterial communities, and specifically the pathogens Methicillin-resistant Staphylococcus aureus (MRSA) and Clostridioides difficile (C. difficile), were present on window components of exterior-facing windows inside patient rooms, and whether relative light exposure (direct or indirect) was associated with changes in bacterial communities on those hospital surfaces. Environmental samples were collected from 30 patient rooms in a single ward at Oregon Health & Science University (OHSU) in Portland, Oregon, USA. Sampling locations within each room included the window glass surface, both sides of the window curtain, two surfaces of the window frame, and the air return grille. Viable bacterial abundances were quantified using qPCR, and community composition was assessed using Illumina MiSeq sequencing of the 16S rRNA gene V3/V4 region. Viable bacteria occupied all sampled locations, but was not associated with a specific hospital surface or relative sunlight exposure. Bacterial communities were similar between window glass and the rest of the room, but had significantly lower Shannon Diversity, theorized to be related to low nutrient density and resistance to bacterial attachment of glass compared to other surface materials. Rooms with windows that were facing west demonstrated a higher abundance of viable bacteria than those facing other directions, potentially because at the time of sampling (morning) west-facing rooms had not yet been exposed to sunlight that day. Viable C. difficile was not detected and viable MRSA was detected at very low abundance. Bacterial abundance was negatively correlated with distance from the central staff area containing the break room and nursing station. In the present study, it can be assumed that there is more human traffic in the center of the ward, and is likely responsible for the observed gradient of total abundance in rooms along the ward, as healthcare staff both deposit more bacteria during activities and affect microbial transit indoors. Overall, hospital window components possess similar microbial communities to other previously identified room locations known to act as reservoirs for microbial agents of hospital-associated infections. [ABSTRACT FROM AUTHOR]

Since the advent of soap, personal hygiene practices have revolved around removal, sterilization, and disinfection—both of visible soil and microscopic organisms—for a myriad of cultural, aesthetic, or health‐related reasons. Cleaning methods and products vary widely in their recommended use, effectiveness, risk to users or building occupants, environmental sustainability, and ecological impact. Advancements in science and technology have facilitated in‐depth analyses of the indoor microbiome, and studies in this field suggest that the traditional "scorched‐earth cleaning" mentality—that surfaces must be completely sterilized and prevent microbial establishment—may contribute to long‐term human health consequences. Moreover, the materials, products, activities, and microbial communities indoors all contribute to, or remove, chemical species to the indoor environment. This review examines the effects of cleaning with respect to the interaction of chemistry, indoor microbiology, and human health. [ABSTRACT FROM AUTHOR]

Currently, there is no manual blind control guideline used consistently throughout the energy modeling community. This paper identifies and compares five manual blind control algorithms with unique control patterns and reports blind occlusion, rate of change data, and annual building energy consumption. The blind control schemes detailed here represent five reasonable candidates for use in lighting and energy simulation based on difference driving factors. This study was performed on a medium-sized office building using EnergyPlus with the internal daylight harvesting engine. Results show that applying manual blind control algorithms affects the total annual consumption of the building by as much as 12.5% and 11.5% for interior and exterior blinds respectively, compared to the Always Retracted blinds algorithm. Peak demand was also compared showing blind algorithms affected zone load sizing by as much as 9.8%. The alternate algorithms were tested for their impact on American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) Guideline 14 calibration metrics and all models were found to differ from the original calibrated baseline by more than the recommended ±15% for coefficient of variance of the mean square error (CVRMSE) and ±5% for normalized mean bias error (NMBE). The paper recommends that energy modelers use one or more manual blind control algorithms during design stages when making decisions about energy efficiency and other design alternatives. [ABSTRACT FROM AUTHOR]

Highlights: [•] PIR motion sensor data was analyzed to identify occupant behavior. [•] A total of 629 sensors were analyzed in the large commercial office building. [•] Private offices were analyzed in detail to identify changes throughout the year. [•] A 46% difference was found between private offices and ASHRAE reference occupancy. [ABSTRACT FROM AUTHOR]

Abstract: There is no comprehensive consensus about the way people operate blinds or the motivating factors that influence their decisions. However, there is a substantial body of research, encompassing data from more than 50 buildings worldwide, that offers guidance. Patterns of blind use can affect the energy consumption of buildings substantially and therefore energy and daylighting simulations that do not account properly for these blind use patterns will have greater error. An outline for a new more nuanced model for simulation-based blind control is offered. Specifically, this paper reviews the energy implications of blind use, blind occlusion and rate of change from field studies, specific quantitative measures influencing user blind control, investigations into user acceptance of automated blind control, and finally conclusions and knowledge gaps are summarized and suggested next steps for research are provided. Addressing these gaps is critical for the continued progress of the energy efficiency movement. [Copyright &y& Elsevier]

Volatile organic compound (VOC) emissions from indoor sources are large determinants of the indoor air quality (IAQ) and occupant health. Cross-laminated timber (CLT) is a panelized engineered wood product often left exposed as an interior surface finish. As a certified structural building product, CLT is currently exempt from meeting VOC emission limits for composite wood products and confirming emissions through California Department of Public Health (CDPH) Standard Method testing. In this study, small chamber testing was conducted to evaluate VOC emissions from three laboratory-produced CLT samples: One bonded with a new soy-based cold-set adhesive; a second bonded with a commercially available polyurethane (PUR) adhesive; and the third assembled without adhesive using dowels. A fourth commercially-produced eight-month-old sample bonded with melamine formaldehyde (MF) adhesive was also tested. All four samples were produced with Douglas-fir. The test results for the three laboratory-produced samples demonstrated VOC emissions compliance with the reference standard. The commercially-produced and aged CLT sample bonded with MF adhesive did not meet the acceptance criterion for formaldehyde of ≤9.0 µg/m3. The estimated indoor air concentration of formaldehyde in an office with the MF sample was 54.4 µg/m3; the results for the soy, PUR, and dowel samples were all at or below 2.5 µg/m3. [ABSTRACT FROM AUTHOR]

A broad range of building performance monitoring, sampling, and evaluation was conducted periodically after construction and spanning more than a year, for an occupied office building constructed using mass timber elements such as cross-laminated timber (CLT) floor and roof panels, as well as glue-laminated timber (GLT) beams and columns. This case study contributes research on monitoring indoor environmental quality in buildings, describing one of the few studies of an occupied mass timber building, and analyzing data in three areas that impact occupant experience: indoor air quality, bacterial community composition, and floor vibration. As a whole, the building was found to perform well. Volatile organic compounds (VOCs), including formaldehyde, were analyzed using multiple methods. Formaldehyde was found to be present in the building, though levels were below most recommended exposure limits. The source of formaldehyde was not able to be identified in this study. The richness of the bacterial community was affected by the height of sampling with respect to the floor, and richness and composition was affected by the location within the building. Floor vibration was observed to be below recognized human comfort thresholds. [ABSTRACT FROM AUTHOR]

• Thermal mass located near ventilation inlets lost more heat through NVM at night. • Automated NVM can improve energy efficiency, but also provides opportunity for error. • Periodic commissioning is recommended to ensure correct NVM function. Summer temperature extremes are expected to increase during the next century. Integrating night ventilation of mass (NVM) strategies in new 'smart' buildings could increase resilience to warming temperatures and reduce reliance on mechanical cooling. However, designing and operating buildings with NVM is challenging due to the complexity of interacting variables and difficulty of accurately measuring and predicting them, particularly when using automated controls and sensors. In this study we evaluated NVM performance by monitoring two night-ventilated classrooms in a mixed-mode smart academic building during October 2014 and June–July 2016. We investigated whether NVM systems were operating as intended, altered operation as needed to match design intent, and compared NVM efficacy during incorrect and corrected operation. We calculated the amount of heat NVM removed from each room overnight and visualized gradients of heat removal across the mass surface. We found that incorrect building automation system (BAS) operation during June 2016 resulted in overuse of mechanical cooling, while corrected operation later in July reduced the number of hours mechanical cooling was required, although average outdoor temperatures were higher. Our results also showed greatest overnight reductions in mass surface temperatures in locations nearest to the air inlets on the exterior south-facing walls. This critical evaluation quantifies the agreement between NVM performance as modeled during the design phase and during post-occupancy operation several years after construction. We conclude that the observed performance gap may be addressed through periodic or continuous re-commissioning. [ABSTRACT FROM AUTHOR]

Coordination of efforts to assess the challenges and pain points felt by industries from around the globe working to reduce COVID-19 transmission in the indoor environment as well as innovative solutions applied to meet these challenges is mandatory. Indoor infectious viral disease transmission (such as coronavirus, norovirus, influenza) is a complex problem that needs better integration of our current knowledge and intervention strategies. Critical to providing a reduction in transmission is to map the four core technical areas of environmental microbiology, transmission science, building science, and social science. To that end a three-stage science and innovation Summit was held to gather information on current standards, policies and procedures applied to reduce transmission in built spaces, as well as the technical challenges, science needs, and research priorities. The Summit elucidated steps than can be taken to reduce transmission of SARS-CoV-2 indoors and calls for significant investments in research to enhance our knowledge of viral pathogen persistence and transport in the built environment, risk assessment and mitigation strategy such as processes and procedures to reduce the risk of exposure and infection through building systems operations, biosurveillance capacity, communication form leadership, and stakeholder engagement for optimal response. These findings reflect the effective application of existing knowledge and standards, emerging science, and lessons-learned from current efforts to confront SARS-CoV-2., Competing Interests: KM and YH were affiliated to the commercial company HWC Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Morrow, Packman, Martinez, Van Den Wymelenberg, Goeres, Farmer, Mitchell, Ng, Hazi, Schoch-Spana, Quinn, Bahnfleth and Olsiewski.)

With the rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that results in coronavirus disease 2019 (COVID-19), corporate entities, federal, state, county, and city governments, universities, school districts, places of worship, prisons, health care facilities, assisted living organizations, daycares, homeowners, and other building owners and occupants have an opportunity to reduce the potential for transmission through built environment (BE)-mediated pathways. Over the last decade, substantial research into the presence, abundance, diversity, function, and transmission of microbes in the BE has taken place and revealed common pathogen exchange pathways and mechanisms. In this paper, we synthesize this microbiology of the BE research and the known information about SARS-CoV-2 to provide actionable and achievable guidance to BE decision makers, building operators, and all indoor occupants attempting to minimize infectious disease transmission through environmentally mediated pathways. We believe this information is useful to corporate and public administrators and individuals responsible for building operations and environmental services in their decision-making process about the degree and duration of social-distancing measures during viral epidemics and pandemics., (Copyright © 2020 Dietz et al.)

Humans purposefully and inadvertently introduce antimicrobial chemicals into buildings, resulting in widespread compounds, including triclosan, triclocarban, and parabens, in indoor dust. Meanwhile, drug-resistant infections continue to increase, raising concerns that buildings function as reservoirs of, or even select for, resistant microorganisms. Support for these hypotheses is limited largely since data describing relationships between antimicrobials and indoor microbial communities are scant. We combined liquid chromatography-isotope dilution tandem mass spectrometry with metagenomic shotgun sequencing of dust collected from athletic facilities to characterize relationships between indoor antimicrobial chemicals and microbial communities. Elevated levels of triclosan and triclocarban, but not parabens, were associated with distinct indoor microbiomes. Dust of high triclosan content contained increased Gram-positive species with diverse drug resistance capabilities, whose pangenomes were enriched for genes encoding osmotic stress responses, efflux pump regulation, lipid metabolism, and material transport across cell membranes; such triclosan-associated functional shifts have been documented in laboratory cultures but not yet from buildings. Antibiotic-resistant bacterial isolates were cultured from all but one facility, and resistance often increased in buildings with very high triclosan levels, suggesting links between human encounters with viable drug-resistant bacteria and local biocide conditions. This characterization uncovers complex relationships between antimicrobials and indoor microbiomes: some chemicals elicit effects, whereas others may not, and no single functional or resistance factor explained chemical-microbe associations. These results suggest that anthropogenic chemicals impact microbial systems in or around buildings and their occupants, highlighting an emergent need to identify the most important indoor, outdoor, and host-associated sources of antimicrobial chemical-resistome interactions. IMPORTANCE The ubiquitous use of antimicrobial chemicals may have undesired consequences, particularly on microbes in buildings. This study shows that the taxonomy and function of microbes in indoor dust are strongly associated with antimicrobial chemicals-more so than any other feature of the buildings. Moreover, we identified links between antimicrobial chemical concentrations in dust and culturable bacteria that are cross-resistant to three clinically relevant antibiotics. These findings suggest that humans may be influencing the microbial species and genes that are found indoors through the addition and removal of particular antimicrobial chemicals.