Impact of respiratory aerosol size and number distribution on the relative importance of different routes in SARS-CoV-2 transmission

Exploring the relative importance of different routes in SARS-CoV-2 transmission is crucial in infection prevention. However, even in the same environmental setting, the relative importance of different routes has varied in different studies. We hypothesize that respiratory aerosol size and number distribution might play a key role. In this study, size and number distribution of respiratory droplets emitted from breathing, talking, and coughing were identified from PubMed and Web of Science. The infection risk of SARS-CoV-2 via airborne, droplet, and fomite transmission routes was modeled in a household and a healthcare setting. The relative importance of three routes varied with different size distributions in both settings. Generally, the contribution of the airborne route increased with the volume percentage of respirable droplets emitted. And the increase of the total number of emitted droplets leads to an increase in the contribution of tdroplet route. In the healthcare setting, as the total number of emitted droplets increased from 110 to 4,973, the contribution of droplet route increased from 62.24% to 98.11%. Next, by considering the combination of breathing, coughing, and talking when the infected person was asymptomatic, the airborne route predominated over the droplet and contact routes. When the infected person had developed symptoms, that is, cough, the droplet route played a dominant role in SARS-CoV-2 transmission. In conclusion, risk analyses will be improved with improved sampling methods that enable characterization of viruses within respiratory droplets of different sizes.

Aerosol and surface contamination assessment of a novel ventilated infectious aerosol containment device

Healthcare personnels (HCPs) are at risk of respiratory infectious diseases during patient care activities. HCPs rely primarily on personal protective equipment to prevent pathogen exposures, but there is a need to develop alternative, or complementary control strategies, including engineering controls. The objective of this study was to evaluate the ability of the 3 designs (denoted D1A, D1B, and D2) of the University of Utah Containment Ventilation for Exposure Reduction (U-COVER), a protective barrier enclosure device to contain respirable aerosols when placed over a simulated patient. The 2 primary performance metrics were the percent reduction in: (i) the concentration of respirable aerosols in the simulated breathing zone of an HCP, and (ii) surface contamination outside the device, which were tested using salt aerosols and fluorescein aerosols, respectively. Briefly, salt or fluorescein aerosols were generated as though expelled by a prone patient under 3 conditions: (i) no device (control), (ii) with the device but without exhaust ventilation, and (iii) with the device with exhaust ventilation. Device D2 was also tested under simulated use conditions, in which cardboard "arms" were placed inside the device ports. All 3 device designs showed the ability to reduce particle concentrations in the simulated HCP breathing zone and on surfaces by >99% with exhaust ventilation compared to the control condition. Without exhaust ventilation, device performance was lower and highly variable. Under simulated use conditions, device D2 reduced particle concentrations in the simulated HCP breathing zone by ≥91% and on surfaces by >99% relative to control for all combinations of "arms" tested. The U-COVER device demonstrates excellent aerosol containment and warrants further testing with dynamic simulated or actual use conditions.

Gender aspects in occupational exposure and health studies

While sex is a biological attribute associated with physical and physiological features, gender refers to socially constructed roles, behaviors, expressions, and identities. On the biological side, males and females differ concerning hormonal and anatomical differences, and It is therefore plausible occupational exposure may act differently on males and females. In contrast, gender may influence the work organization, work environment conditions and exposures, and employment conditions, leading people of different genders to perform different jobs or job tasks, be exposed to different stressors, and work under different employment terms. Traditionally, occupational exposures have been assessed without considering how exposures may differ by sex or gender. Early research focused on occupations that primarily employed men. However, women have entered occupations historically dominated by men, leading to emerging exploration of gender differences in exposure. Some women-dominated occupations have become the focus of intensive research activity. In the Annals, the number of articles including sex and gender issues has increased dramatically over time, with only two published prior to 1980, and 70 in the 2010s, and with a special issue dedicated to Gender, Work, and Health in 2018 where the editors highlighted a need to improve assessment of gender and sex identities to allow for more nuanced knowledge to elucidate the role of work organization and contextual factors about gender, work exposures, and health. Females, on average, have different body dimensions than males, which affects how well workplaces and personal protective equipment (PPE) fit females, and there remains a need for further improvements to ensure that females are protected equally well. On the other hand, females tend to comply more frequently with PPE requirements than men highlighting the need for gender-specific initiatives in order to increase PPE performance and compliance. In conclusion, there is still work to do in order to fill in the existing knowledge gap with regard to sex, gender, and work, but there are promising initiatives and the field is progressing.

Exposure frequency, intensity, and duration: What we know about work-related asthma risks for healthcare workers from cleaning and disinfection

The objective of this review was to scope the current evidence base related to three exposure assessment concepts: frequency, intensity, and duration (latency) for cleaning and disinfection exposures in healthcare and subsequent work-related asthma risks. A search strategy was developed addressing intersections of four main concepts: (1) work-related asthma; (2) occupation (healthcare workers/nurses); (3) cleaning and disinfection; and (4) exposure. Three databases were searched: Embase, PubMed, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) database. Data were extracted related to three main components of risk assessment: (1) exposure frequency, (2) exposure intensity, and (3) exposure duration. Latency data were analyzed using an exponential distribution fit, and extracted concentration data were compared to occupational exposure limits. The final number of included sources from which data were extracted was 133. Latency periods for occupational asthma were exponentially distributed, with a mean waiting time (1/λ) of 4.55 years. No extracted concentration data were above OELs except for some formaldehyde and glutaraldehyde concentrations. Data from included sources also indicated some evidence for a dose-response relationship regarding increased frequency yielding increased risk, but this relationship is unclear due to potential confounders (differences in role/task and associated exposure) and the healthy worker effect. Data priority needs to include linking concentration data to health outcomes, as most current literature does not include both types of measurements in a single study, leading to uncertainty in dose-response relationships.

Alanine response to low energy synchrotron x-ray radiation

Objective. The radiation response of alanine is very well characterized in the MV photon energy range where it can be used to determine the dose delivered with an accuracy better than 1%, making it suitable as a secondary standard detector in cancer radiation therapy. This is not the case in the very low energy keV x-ray range where the alanine response is affected by large uncertainties and is strongly dependent on the x-ray beam energy. This motivated the study undertaken here.Approach. Alanine pellets with a nominal thickness of 0.5 mm and diameter of 5 mm were irradiated with monoenergetic x-rays at the Diamond Light Source synchrotron, to quantify their response in the 8-20 keV range relative to60Co radiation. The absorbed dose to graphite was measured with a small portable graphite calorimeter, and the DOSRZnrc code in the EGSnrc Monte Carlo package was used to calculate conversion factors between the measured dose to graphite and the absorbed dose to water delivered to the alanine pellets. GafChromic EBT3 films were used to measure the beam profile for modelling in the MC simulations.Main results. The relative responses measured in this energy range were found to range from 0.616 to 0.643, with a combined relative expanded uncertainty of 3.4%-3.5% (k= 2), where the majority of the uncertainty originated from the uncertainty in the alanine readout, due to the small size of the pellets used.Significance. The measured values were in good agreement with previously published data in the overlapping region of x-ray energies, while this work extended the dataset to lower energies. By measuring the response to monoenergetic x-rays, the response to a more complex broad-spectrum x-ray source can be inferred if the spectrum is known, meaning that this work supports the establishment of alanine as a secondary standard dosimeter for low-energy x-ray sources.

Aerosol containment device design considerations and performance evaluation metrics

BACKGROUND

Spurred by the Coronavirus infectious disease 2019 pandemic, aerosol containment devices (ACDs) were developed to capture infectious respiratory aerosols generated by patients at their source. Prior reviews indicated that such devices had low evidence of effectiveness, but did not address how ACDs should be evaluated, how well they should perform, nor have clearly defined performance standards. Towards developing design criteria for ACDs, two questions were posed: 1) What characteristics have guided the design of ACDs? 2) How have these characteristics been evaluated?

METHODS

A scoping review was performed consistent with PRISMA guidelines. Data were extracted with respect to general study information, intended use of the device, device design characteristics and evaluation.

RESULTS

Fifty-four articles were included. Evaluation was most commonly performed with respect to device aerosol containment (n = 31, 61%), with only 5 (9%), 3 (6%) and 8 (15%) formally assessing providing experience, patient experience and procedure impact, respectively. Nearly all of the studies that explored provider experience and procedure impact studied intubation. Few studies provided a priori performance criteria for any evaluation metric, or referenced any external guidelines by which to bench mark performance.

CONCLUSION

With respect to aerosol containment, ACDs should reduce exposure among HCP with the device compared with the absence of the device, and provide ≥90% reduction in respirable aerosols, equivalent in performance to N95 filtering facepiece respirators, if the goal is to reduce reliance on personal protective equipment. The ACD should not increase awkward or uncomfortable postures, or adversely impact biomechanics of the procedure itself as this could have implications for procedure outcomes. A variety of standardized instruments exist to assess the experience of patients and healthcare personnel. Integration of ACDs into routine clinical practice requires rigorous studies of aerosol containment and the user experience.

Health and Safety Regulations for COVID-19: A Policy Analysis

The COVID-19 pandemic spurred some regulators in the USA to require occupational health and safety programs to prevent COVID-19 transmission in workplaces. The objective of this study was to describe such state and federal regulations enacted between January 2020 and January 2022. Regulations, including emergency temporary standards (ETS) and permanent standards, were identified through a search of Nexis Uni and Bloomberg Law and review of US OSHA websites and the Federal Register. Full texts were reviewed for regulatory scope, hazard and exposure definitions, determination of exposure or risk levels, and control strategies. Four state (California, Michigan, Virginia, and Oregon) and two federal regulations were identified. All regulations described respiratory aerosols as the primary source of SARS-CoV-2 and recognized person-to-person transmission by droplet, airborne, and contact routes. Only the US OSHA ETS for healthcare explicitly stated that inhalation of respiratory particles was the most likely method of COVID-19 transmission. The Virginia, Michigan, and Oregon regulations described different categories of risk defined by exposure frequency and duration or specific workplace activities. California described exposure as places and times when employees come into contact or congregate with other people. The US OSHA ETS for healthcare described exposure as involving close contact with suspected or confirmed COVID-19 patients. While all of the state regulations required strategies from across the hierarchy, only the Virginia regulations specifically incorporated the hierarchy of controls. Only the California and Virginia regulations explicitly linked control strategies to the transmission route, while Virginia demarcated control strategies by risk level. Oregon linked risk level to occupancy levels and physical distancing requirements and referred to the use of a layered approach for transmission control. The US OSHA ETS for healthcare defined droplet and airborne precautions but made no mention of the hierarchy of controls or risk levels. Respirators were discussed in most of the regulations. The first Michigan regulation explicitly required respirators appropriate to exposure risk. The California regulations noted that respirators protect the wearer while face coverings protect people around the wearer. These regulations offer insights for a permanent US OSHA infectious disease regulation, such as the need to consider a range of transmission modes including near- and far-range aerosol inhalation, endemic and novel pathogens, workplaces beyond healthcare settings, factors that contribute to exposure and risk, the hierarchy of controls, the role of vaccination, and the importance of written exposure assessment and infection prevention plans.

A Novel Application of Risk-Risk Tradeoffs in Occupational Health: Nurses' Occupational Asthma and Infection Risk Perceptions Related to Cleaning and Disinfection during COVID-19

BACKGROUND

Nurses face the risk of new onset occupational asthma (OA) due to exposures to cleaning and disinfection (C&D) agents used to prevent infections in healthcare facilities. The objective of this study was to measure nurses' preferences when presented with simultaneous OA and respiratory viral infection (e.g., COVID-19) risks related to increased/decreased C&D activities.

METHODS

Nurses working in healthcare for ≥1 year and without physician-diagnosed asthma were recruited for an online anonymous survey, including four risk-risk tradeoff scenarios between OA and respiratory infection with subsequent recovery (Infect and Recovery) or subsequent death (Infect and Death). Nurses were presented with baseline risks at hypothetical "Hospital 1", and were asked to choose Hospital 2 (increased OA risk to maintain infection risk), Hospital 3 (increased infection risk to maintain OA risk), or indicate that they were equally happy.

RESULTS

Over 70% of nurses were willing to increase infection risk to maintain baseline OA risk if they were confident they would recover from the infection. However, even when the risk of infection leading to death was much lower than OA, most nurses were not willing to accept a larger (but still small) risk of death to avoid doubling their OA risk. Age, work experience, and ever having contracted or knowing anyone who has contracted a respiratory viral infection at work influenced choices.

CONCLUSIONS

We demonstrate the novel application of a risk-risk tradeoff framework to address an occupational health issue. However, more data are needed to test the generalizability of the risk preferences found in this specific risk-risk tradeoff context.

Assessing Patterns of Body Contamination after Personal Protective Equipment Removal among Healthcare Workers: A Scoping Review

BACKGROUND

It is now widely recognized that healthcare personnel (HCP) are at risk of contamination with pathogens during personal protective equipment (PPE) doffing. Studies of this phenonemona, have utilized a variety of PPE ensembles, doffing methods and experimental methods.

METHODS

A scoping review was performed, consistent with PRISMA guidance. The PubMed and sciVerse Scopus databases were searched using an a priori search strategy. Data were extracted for analysis using the matrix method, and then a narrative analysis performed. Articles were classified based on PPE ensemble.

RESULTS

Only 19 of 151 articles were included in the final anlaysis. All included studies reported some post-doffing contamination, and this contamination was most frequently observed on the hands, wrist, face and neck. Reviewed studies used a variety of tracer contaminants, PPE ensembles, doffing protocols, tracer assessment locations and methods, making it difficult to identify patterns across studies.

DISCUSSION&CONCLUISONS

Additional research is needed to improve study methodology related to the selection and placement of tracers to ensure sensitive detection of post-doffing contamination, compare how specific doffing procedures or pieces of PPE influence post-doffing contamination, and to understand what post-doffing contamination means for patient and HCP infection risk.

Exploring spatial averaging of contamination in fomite microbial transfer models and implications for dose

BACKGROUND

When modeling exposures from contact with fomites, there are many choices in defining the sizes of compartments representing environmental surfaces and hands, and the portions of compartments involved in contacts. These choices impact dose estimates, yet there is limited guidance for selection of these model parameters.

OBJECTIVE

The study objective was to explore methods for representing environmental surface and hand contact areas in exposure models and implications for estimated doses.

METHODS

A simple scenario was used: an individual using their hands to contact their face and two microbially contaminated environmental surfaces. Four models were developed to explore different compartmentalization strategies: (1) hands and environmental surfaces each represented by one compartment, (2) hands represented by two compartments (fingertips vs. non-fingertip areas) while environmental surfaces were represented by one compartment, (3) hands represented by a single compartment and environmental surfaces represented by two compartments, and (4) hands and environmental surfaces each represented by two compartments. Sensitivity analyses were conducted to evaluate the influence of heterogeneous surface contact frequency, hand contact type, and hand dominance on dose.

RESULTS

Estimated doses were greatest when hand areas and environmental surfaces were each represented by two compartments, indicating that surface area "dilutes" contaminant concentration and decreases estimated dose.

SIGNIFICANCE

Model compartment designations for hands and environmental surfaces affect dose estimation, but more human behavior data are needed.

IMPACT STATEMENT

A common problem for exposure models describing exposures via hand-to-surface contacts occurs in the way that estimated contamination across human skin (usually hands) or across environmental surfaces is spatially averaged, as opposed to accounting for concentration changes across specific parts of the hand or individual surfaces. This can lead to the dilution of estimated contaminants and biases in estimated doses in risk assessments. The magnitude of these biases and implications for the accuracy in risk assessments are unknown. We quantify differences in dose for various strategies of compartmentalizing environmental surfaces and hands to inform guidance on future exposure model development.

Environmental and occupational health on the Navajo Nation: a scoping review

A scoping review was performed to answer: what environmental health concerns have been associated with adverse health outcomes in the Navajo Nation? The review focused on occupational and ambient environmental exposures associated with human industrial activities. The search strategy was implemented in PubMed, and two investigators screened the retrieved literature. Thirteen studies were included for review. Data were extracted using the matrix method. Six studies described associations between work in uranium mining and cancer. Six studies focused on environmental exposures to uranium mine waste and other metals, with outcomes that included biological markers, kidney disease, diabetes and hypertension, and adverse birth outcomes. One study explored occupational exposure to Sin Nombre Virus and infection. Most research has focused on the health effects of uranium, where occupational exposures occurred among miners and environmental exposures are a legacy of uranium mining and milling. Gaps exist with respect to health outcomes associated with current occupations and the psychosocial impact of environmental hazards. Other environmental exposures and hazards are known to exist on the Navajo Nation, which may warrant epidemiologic research.

Efficacy of EPA-registered disinfectants against two human norovirus surrogates and Clostridioides difficile endospores

AIMS

To determine the efficacy of a panel of nine EPA-registered disinfectants against two human norovirus (HuNoV) surrogates (feline calicivirus [FCV] and Tulane virus [TuV]) and Clostridioides difficile endospores.

METHODS AND RESULTS

Nine EPA-registered products, five of which contained H2 O2 as active ingredient, were tested against infectious FCV, TuV and C. difficile endospores using two ASTM methods, a suspension and carrier test. Efficacy claims against FCV were confirmed for 8 of 9 products. The most efficacious product containing H2 O2 as ingredient achieved a >5.1 log reduction of FCV and >3.1 log reduction of TuV after 5 min, and >6.0 log reduction of C. difficile endospores after 10 min. Of the five products containing H2 O2 , no strong correlation (R2  = 0.25, p = 0.03) was observed between disinfection efficacy and H2 O2 concentration. Addition of 0.025% ferrous sulphate to 1% H2 O2 solution improved efficacy against FCV, TuV and C. difficile.

CONCLUSION

Disinfectants containing H2 O2 are the most efficacious disinfection products against FCV, TuV and C. difficile endospores. Product formulation, rather than the concentration of H2 O2 in a product, impacts the efficacy of a disinfection product.

SIGNIFICANCE AND IMPACT OF STUDY

H2 O2 -based disinfectants are efficacious against surrogate viruses for HuNoV and C. difficile endospores.

Making copper, silver and gold fullerene cages breathe

We show that optical properties change when the fullerene structures of Au₃₂, Cu₃₂and Ag₃₂inflate and deflate. We first observe significant differences in the extinction spectra employing a classical approach based on the Green's dyadic method. By means of real-time time-dependent density functional theory. We continue to calculate the optical spectrum (OP) via aδ-kick simulation, comparing results with the ground-state energetic property the HOMO-LUMO (HL) gap. Red-shift of the OP is expected as the fullerenes inflate, with only ±10% change in the size. As the fullerene breathes, a 0.8 eV shift in the first peak position could be observed in the gold nanoparticle. Ag has a smoother behaviour than both Au and Cu. We have also found changes in the optical spectra can not be directly interpreted as a result of changes in the HL gap.

Influence of face shields on exposures to respirable aerosol

The objective of this study was to determine the influence of face shields on the concentration of respirable aerosols in the breathing zone of the wearer. The experimental approach involved the generation of poly-dispersed respirable test dust aerosol in a low-speed wind tunnel over 15 min, with a downstream breathing mannequin. Aerosol concentrations were measured in the breathing zone of the mannequin and at an upstream location using two laser spectrophotometers that measured particle number concentration over the range 0.25-31 µm. Three face shield designs were tested (A, B, and C) and were positioned on the mannequin operated at a high and low breathing rate. Efficiency-the reduction in aerosol concentration in the breathing zone-was calculated as a function of particle size and overall, for each face shield. Face shield A, a bucket hat with flexible shield, had the highest efficiency, approximately 95%, while more traditional face shield designs had efficiency 53-78%, depending on face shield and breathing rate. Efficiency varied by particle size, but the pattern differed among face shield designs. Face shields decreased the concentration of respirable aerosols in the breathing zone when aerosols were carried perpendicular to the face. Additional research is needed to understand the impact of face shield position relative to the source.

Artificial Stone Silicosis: Need for Improved Controls

Silicosis is emerging as a rapidly progressing occupational disease among young workers who fabricate and install artificial stone. Artificial stone is a composite material characterized by high levels of crystalline silica. Recent research has demonstrated high levels of crystalline silica exposures, particularly during dry cutting and finishing tasks, and an association between exposure intensity and duration and adverse respiratory outcomes. Occupational hygienists must move forward with development and implementation of control strategies, with consideration for the conditions of artificial stone work that may make control implementation challenging.

Transmission of Respiratory Viral Diseases to Health Care Workers: COVID-19 as an Example

Health care workers (HCWs) can acquire infectious diseases, including coronavirus disease 2019 (COVID-19), from patients. Herein, COVID-19 is used with the source–pathway–receptor framework as an example to assess evidence for the role of aerosol transmission and indirect contact transmission of viral respiratory infectious diseases. Evidence for both routes is strong for COVID-19 and other respiratory viruses, but aerosol transmission is likely dominant for COVID-19. Key knowledge gaps about transmission processes and control strategies include the distribution of viable virus among respiratory aerosols of different sizes, the mechanisms and efficiency by which virus deposited on the facial mucous membrane moves to infection sites inside the body, and the performance of source controls such as face coverings and aerosol containment devices. To ensure that HCWs are adequately protected from infection, guidelines and regulations must be updated to reflect the evidence that respiratory viruses are transmitted via aerosols.

Expected final online publication date for the Annual Review of Public Health, Volume 43 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Feasibility of a High-Volume Filter Sampler for Detecting SARS-CoV-2 RNA in COVID-19 Patient Rooms

Aerosolization of SARS-CoV-2 by COVID-19 patients can put healthcare workers and susceptible individuals at risk of infection. Air sampling for SARS-CoV-2 has been conducted in healthcare settings, but methods vary widely and there is need for improvement. The objective of this study was to evaluate the feasibility of using a high-volume filter sampler, BioCapture z720, to detect SARS-CoV-2 in COVID-19 patient rooms in a medical intensive care unit, a dedicated COVID-19 ward, and at nurses’ stations. In some locations, the BioSpot-VIVAS, known for high efficiency in the collection of virus-containing bioaerosols, was also operated. The samples were processed for SARS-CoV-2 RNA with multi-plex nested polymerase chain reaction. One of 28 samples collected with the high-volume filter sampler was positive for SARS-CoV-2; all 6 samples collected with BioSpot-VIVAS were negative for SARS-CoV-2. The high-volume filter sampler was more portable and less intrusive in patient rooms than the BioSpot-VIVAS, but limits of detection remain unknown for this device. This study will inform future work to evaluate the reliability of these types of instruments and inform best practices for their use in healthcare environments for SARS-CoV-2 air sampling.

Comparing approaches for modelling indirect contact transmission of infectious diseases

Mathematical models describing indirect contact transmission are an important component of infectious disease mitigation and risk assessment. A model that tracks microorganisms between compartments by coupled ordinary differential equations or a Markov chain is benchmarked against a mechanistic interpretation of the physical transfer of microorganisms from surfaces to fingers and subsequently to a susceptible person's facial mucosal membranes. The primary objective was to compare these models in their estimates of doses and changes in microorganism concentrations on hands and fomites over time. The abilities of the models to capture the impact of episodic events, such as hand hygiene, and of contact patterns were also explored. For both models, greater doses were estimated for the asymmetrical scenarios in which a more contaminated fomite was touched more often. Differing representations of hand hygiene in the Markov model did not notably impact estimated doses but affected pathogen concentration dynamics on hands. When using the Markov model, losses due to hand hygiene should be handled as separate events as opposed to time-averaging expected losses. The discrete event model demonstrated the effect of hand-to-mouth contact timing on the dose. Understanding how model design influences estimated doses is important for advancing models as reliable risk assessment tools.

Community daytime noise pollution and socioeconomic differences in Chicago, IL

Environmental noise may affect hearing and a variety of non-auditory disease processes. There is some evidence that, like other environmental hazards, noise may be differentially distributed across communities based on socioeconomic status. We aimed to a) predict daytime noise pollution levels and b) assess disparities in daytime noise exposure in Chicago, Illinois. We measured 5-minute daytime noise levels (L_{eq, 5-min}) at 75 randomly selected sites in Chicago in March, 2019. Geographically-based variables thought to be associated with noise were obtained, and used to fit a noise land-use regression model to estimate the daytime environmental noise level at the centroid of the census blocks. Demographic and socioeconomic data were obtained from the City of Chicago for the 77 community areas, and associations with daytime noise levels were assessed using spatial autoregressive models. Mean sampled noise level (L_{eq, 5-min}) was 60.6 dBA. The adjusted R² and root mean square error of the noise land use regression model and the validation model were 0.60 and 4.67 dBA and 0.51 and 5.90 dBA, respectively. Nearly 75% of city blocks and 85% of city communities have predicted daytime noise level higher than 55 dBA. Of the socioeconomic variables explored, only community per capita income was associated with mean community predicted noise levels, and was highest for communities with incomes in the 2^nd quartile. Both the noise measurements and land-use regression modeling demonstrate that Chicago has levels of environmental noise likely contributing to the total burden of environmental stressors. Noise is not uniformly distributed across Chicago; it is associated with proximity to roads and public transportation, and is higher among communities with mid-to-low incomes per capita, which highlights how socially and economically disadvantaged communities may be disproportionately impacted by this environmental exposure.

Focused VHEE (very high energy electron) beams and dose delivery for radiotherapy applications

This paper presents the first demonstration of deeply penetrating dose delivery using focused very high energy electron (VHEE) beams using quadrupole magnets in Monte Carlo simulations. We show that the focal point is readily modified by linearly changing the quadrupole magnet strength only. We also present a weighted sum of focused electron beams to form a spread-out electron peak (SOEP) over a target region. This has a significantly reduced entrance dose compared to a proton-based spread-out Bragg peak (SOBP). Very high energy electron (VHEE) beams are an exciting prospect in external beam radiotherapy. VHEEs are less sensitive to inhomogeneities than proton and photon beams, have a deep dose reach and could potentially be used to deliver FLASH radiotherapy. The dose distributions of unfocused VHEE produce high entrance and exit doses compared to other radiotherapy modalities unless focusing is employed, and in this case the entrance dose is considerably improved over existing radiations. We have investigated both symmetric and asymmetric focusing as well as focusing with a range of beam energies.

Respirators, face masks, and their risk reductions via multiple transmission routes for first responders within an ambulance

First responders may have high SARS-CoV-2 infection risks due to working with potentially infected patients in enclosed spaces. The study objective was to estimate infection risks per transport for first responders and quantify how first responder use of N95 respirators and patient use of cloth masks can reduce these risks. A model was developed for two Scenarios: an ambulance transport with a patient actively emitting a virus in small aerosols that could lead to airborne transmission (Scenario 1) and a subsequent transport with the same respirator or mask use conditions, an uninfected patient; and remaining airborne SARS-CoV-2 and contaminated surfaces due to aerosol deposition from the previous transport (Scenario 2). A compartmental Monte Carlo simulation model was used to estimate the dispersion and deposition of SARS-CoV-2 and subsequent infection risks for first responders, accounting for variability and uncertainty in input parameters (i.e., transport duration, transfer efficiencies, SARS-CoV-2 emission rates from infected patients, etc.). Infection risk distributions and changes in concentration on hands and surfaces over time were estimated across sub-Scenarios of first responder respirator use and patient cloth mask use. For Scenario 1, predicted mean infection risks were reduced by 69%, 48%, and 85% from a baseline risk (no respirators or face masks used) of 2.9 × 10-2 ± 3.4 × 10-2 when simulated first responders wore respirators, the patient wore a cloth mask, and when first responders and the patient wore respirators or a cloth mask, respectively. For Scenario 2, infection risk reductions for these same Scenarios were 69%, 50%, and 85%, respectively (baseline risk of 7.2 × 10-3 ± 1.0 × 10-2). While aerosol transmission routes contributed more to viral dose in Scenario 1, our simulations demonstrate the ability of face masks worn by patients to additionally reduce surface transmission by reducing viral deposition on surfaces. Based on these simulations, we recommend the patient wear a face mask and first responders wear respirators, when possible, and disinfection should prioritize high use equipment.

Standards for Surgical Respirators and Masks: Relevance for Protecting Healthcare Workers and the Public During Pandemics

National standards for surgical respirators and masks are written and enforced to protect healthcare workers from particles and microorganisms such as Severe Acute Respriatory Syndrome Coronavirus 2 (SARS-CoV-2). In addition to the ability to filter particles (e.g. filtration efficiency, FE), the standards address breathability (e.g. differential pressure), how well the mask seals to a worker’s face (e.g. fit test), the level of protection from a fluid splash, and other factors. Standards used in the USA, European Union (EU), and China were compared with respect to testing methods and certification criteria. Although there are substantial similarities in standards for respirators, such as surgical N95, FFP2, and KN95 filtering facepiece respirators (FFRs), there are differences with respect to who performs that testing and fit-testing requirements that influence certification. There is greater variation in test methods between countries for surgical (USA) or medical (EU and China) masks than for FFRs. Surgical/medical masks can be certified to different levels of protection. The impact of the similarities and differences in testing methods and certification criteria on FFR and mask performance for protecting healthcare workers from SARS-CoV-2 are discussed, as well as the value of a new standard in the EU for testing fabrics for masks used by the public. Health and safety personnel in healthcare settings must understand the differences between standards so that they can select respirators and masks that provide appropriate protection for healthcare workers.

Evaluating very high energy electron RBE from nanodosimetric pBR322 plasmid DNA damage

This paper presents the first plasmid DNA irradiations carried out with Very High Energy Electrons (VHEE) over 100-200 MeV at the CLEAR user facility at CERN to determine the Relative Biological Effectiveness (RBE) of VHEE. DNA damage yields were measured in dry and aqueous environments to determine that ~ 99% of total DNA breaks were caused by indirect effects, consistent with other published measurements for protons and photons. Double-Strand Break (DSB) yield was used as the biological endpoint for RBE calculation, with values found to be consistent with established radiotherapy modalities. Similarities in physical damage between VHEE and conventional modalities gives confidence that biological effects of VHEE will also be similar-key for clinical implementation. Damage yields were used as a baseline for track structure simulations of VHEE plasmid irradiation using GEANT4-DNA. Current models for DSB yield have shown reasonable agreement with experimental values. The growing interest in FLASH radiotherapy motivated a study into DSB yield variation with dose rate following VHEE irradiation. No significant variations were observed between conventional and FLASH dose rate irradiations, indicating that no FLASH effect is seen under these conditions.

Contribuciones relativas de las vías de transmisión de la COVID-19 entre el personal sanitario que presta atención a pacientes

RESUMENLas vías de transmisión de la COVID-19 desde pacientes infectados al personal de la salud son actualmente objeto de debate, pero su consideración resulta fundamental para la selección del equipo de protección personal. El objetivo de este documento es explorar las contribuciones de tres vías de transmisión-contacto, gota e inhalación-al riesgo de infección de COVID-19 adquirida por el personal sanitario en el ámbito laboral. El método consistió en la evaluación cuantitativa de los riesgos microbianos y de un modelo de exposición cuyos posibles parámetros se basaron en datos específicos del virus SARS-CoV-2 cuando se disponía de ellos. El hallazgo clave fue que las vías de transmisión por gotas e inhalación predominan sobre la vía de contacto, contribuyendo en promedio 35%, 57% y 8.2% a la probabilidad de infección cuando no se usa equipo de protección personal. En promedio, 80% de la exposición a la inhalación ocurre cuando el personal sanitario está cerca de los pacientes. La contribución relativa de las gotas y la inhalación depende de la emisión de SARS-CoV-2 en las partículas respirables (<10 μm) a través de la exhalación, y la inhalación se vuelve predominante, en promedio, cuando la emisión supera las cinco copias genéticas por minuto. La concentración prevista del SARS-CoV-2 en el aire de la habitación del paciente es baja (<1 copia del gen por m³ en promedio) y probablemente se encuentre por debajo del límite de cuantificación de muchos métodos de muestreo del aire. Los resultados demuestran el valor que supone la protección respiratoria del personal sanitario y que el muestreo de campo puede no ser lo suficientemente sensible para verificar la contribución que realiza la inhalación del SARS-CoV-2 al riesgo de infección de COVID-19 adquirida por el personal. La emisión e ineficacia del SARS-CoV-2 en gotas respiratorias de diferente tamaño es aún una brecha en el conocimiento, fundamental para comprender y controlar la transmisión de la COVID-19.

Prácticas de retiro del equipo de protección personal para personal sanitario

RESUMENCuando se retira el equipo de protección personal (EPP), los patógenos pueden transferirse desde el EPP al cuerpo de los trabajadores de la salud, poniendo en riesgo de exposición e infección tanto a ellos mismos como a sus pacientes. Entre marzo de 2017 y abril de 2018 se observaron las prácticas de retirada del EPP del personal sanitario que atendía pacientes con infecciones respiratorias virales en un hospital de atención de enfermedades agudas. Un observador capacitado registró el desempeño del personal sanitario cuando retiraba el EPP dentro de las habitaciones de los pacientes, utilizando una lista de verificación predefinida basada en las directrices de los Centros para el Control y Prevención de Enfermedades (Centers for Disease Control and Prevention, CDC). Se observaron 162 prácticas de retirada durante el cuidado de 52 pacientes infectados con patógenos virales respiratorios. De estos 52 pacientes, 30 estaban en aislamiento por gota y contacto, 21 en aislamiento por gota y uno en aislamiento de contacto. En general, en 90% de los casos la retirada del EPP observada se realizó de manera incorrecta, ya sea en cuanto a la secuencia de retirada, la técnica de retirada o el uso del EPP apropiado. Los errores más comunes consistieron en quitarse la bata por adelante, retirar la pantalla facial de la mascarilla y tocar superficies y EPP potencialmente contaminados durante el proceso. Las desviaciones del protocolo recomendado para retirar el EPP son comunes y pueden aumentar el potencial de contaminación de la ropa o la piel del personal sanitario después de proporcionar atención. Existe una clara necesidad de cambiar el enfoque utilizado para capacitar al personal en las prácticas de retirada del EPP.

Aerosol transmission of SARS-CoV-2? Evidence, prevention and control

As public health teams respond to the pandemic of coronavirus disease 2019 (COVID-19), containment and understanding of the modes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission is of utmost importance for policy making. During this time, governmental agencies have been instructing the community on handwashing and physical distancing measures. However, there is no agreement on the role of aerosol transmission for SARS-CoV-2. To this end, we aimed to review the evidence of aerosol transmission of SARS-CoV-2. Several studies support that aerosol transmission of SARS-CoV-2 is plausible, and the plausibility score (weight of combined evidence) is 8 out of 9. Precautionary control strategies should consider aerosol transmission for effective mitigation of SARS-CoV-2.

Relative contributions of transmission routes for COVID-19 among healthcare personnel providing patient care

The routes of COVID-19 transmission to healthcare personnel from infected patients is the subject of debate, but is critical to the selection of personal protective equipment. The objective of this paper was to explore the contributions of three transmission routes-contact, droplet, and inhalation-to the risk of occupationally acquired COVID-19 infection among healthcare personnel (HCP). The method was quantitative microbial risk assessment, and an exposure model, where possible model parameters were based on data specific to the SARS-CoV-2 virus when available. The key finding was that droplet and inhalation transmission routes predominate over the contact route, contributing 35%, 57%, and 8.2% of the probability of infection, on average, without use of personal protective equipment. On average, 80% of inhalation exposure occurs when HCP are near patients. The relative contribution of droplet and inhalation depends upon the emission of SARS-CoV-2 in respirable particles (<10 µm) through exhaled breath, and inhalation becomes predominant, on average, when emission exceeds five gene copies per min. The predicted concentration of SARS-CoV-2 in the air of the patient room is low (< 1 gene copy per m³ on average), and likely below the limit of quantification for many air sampling methods. The findings demonstrate the value of respiratory protection for HCP, and that field sampling may not be sensitive enough to verify the contribution of SARS-CoV-2 inhalation to the risk of occupationally acquired COVID-19 infection among healthcare personnel. The emission and infectivity of SARS-CoV-2 in respiratory droplets of different sizes is a critical knowledge gap for understanding and controlling COVID-19 transmission.

Cost effectiveness of intraoperative laparoscopic ultrasound for suspected choledocholithiasis; outcomes from a specialist benign upper gastrointestinal unit

INTRODUCTION

Common bile duct stones are present in 10% of patients with symptomatic gallstones. One-third of UK patients undergoing cholecystectomy will have preoperative ductal imaging, commonly with magnetic resonance cholangiopancreatography. Intraoperative laparoscopic ultrasound is a valid alternative but is not widely used. The primary aim of this study was to assess cost effectiveness of laparoscopic ultrasound compared with magnetic resonance cholangiopancreatography.

MATERIALS AND METHODS

A prospective database of all patients undergoing laparoscopic cholecystectomy between 2015 and 2018 at a district general hospital was assessed. Inclusion criteria were all patients, emergency and elective, with symptomatic gallstones and suspicion of common bile duct stones (derangement of liver function tests with or without dilated common bile duct on preoperative ultrasound, or history of pancreatitis). Patients with known common bile duct stones (magnetic resonance cholangiopancreatography or failed endoscopic retrograde cholangiogram) were excluded. Ninety-day morbidity data were also collected.

RESULTS

A total of 420 (334 elective and 86 emergency) patients were suspected to have common bile duct stones and were included in the study. The cost of a laparoscopic ultrasound was £183 per use. The cost of using the magnetic resonance cholangiopancreatography unit was £365 per use. Ten postoperative magnetic resonance cholangiopancreatographies were performed for inconclusive intraoperative imaging. The estimated cost saving was £74,650. Some 128 patients had common bile duct stones detected intraoperatively and treated. There was a false positive rate of 4.7%, and the false negative rate at 90 days was 0.7%. laparoscopic ultrasound use saved 129 bed days for emergency patients and 240 magnetic resonance cholangiopancreatography hours of magnetic resonance imaging.

CONCLUSION

The use of laparoscopic ultrasound during laparoscopic cholecystectomy for the detection of common bile duct stone is safe, accurate and cost effective. Equipment and maintenance costs are quickly offset and hospital bed days can be saved with its use.

A systematic review of the efficacy and safety of second generation antipsychotics in the treatment of mania

Second generation antipsychotic agents are increasingly used in the management of acute mania. A systematic review of the efficacy and safety of these agents, as both monotherapy and in combination with mood stabilisers, was performed to establish the evidence for their use. Randomised controlled trials (RCTs) were critically appraised in more detail than studies that presented lower levels of evidence such as case reports, case series and open label follow up studies. We found 11 RCTs reporting on patients treated with second generation antipsychotics for acute bipolar mania, of which three included randomisation between the second generation antipsychotic and placebo, and eight between a mood stabiliser combined with either the second generation antipsychotic or placebo. Data from non-randomised trials is also presented.

Quantifying the relative impact of contact heterogeneity on MRSA transmission in ICUs - a modelling study

Background

An efficient surface cleaning strategy would first target cleaning to surfaces that make large contributions to the risk of infections.

Methods

In this study, we used data from the literature about methicillin-resistant Staphylococcus aureus (MRSA) and developed an ordinary differential equations based mathematical model to quantify the impact of contact heterogeneity on MRSA transmission in a hypothetical 6-bed intensive care unit (ICU). The susceptible patients are divided into two types, these who are cared by the same nurse as the MRSA infected patient (Type 1) and these who are not (Type 2).

Results

The results showed that the mean MRSA concentration on three kinds of susceptible patient nearby surfaces was significantly linearly associated with the hand-touch frequency (p < 0.05). The noncompliance of daily cleaning on patient nearby high-touch surfaces (HTSs) had the most impact on MRSA transmission. If the HTSs were not cleaned, the MRSA exposure to Type 1 and 2 susceptible patients would increase 118.4% (standard deviation (SD): 33.0%) and 115.4% (SD: 30.5%) respectively. The communal surfaces (CSs) had the least impact, if CSs were not cleaned, the MRSA exposure to Type 1 susceptible patient would only increase 1.7% (SD: 1.3). The impact of clinical equipment (CE) differed largely for two types of susceptible patients. If the CE was not cleaned, the exposure to Type 1 patients would only increase 8.4% (SD: 3.0%), while for Type 2 patients, it can increase 70.4% (SD: 25.4%).

Conclusions

This study provided a framework to study the pathogen concentration dynamics on environmental surfaces and quantitatively showed the importance of cleaning patient nearby HTSs on controlling the nosocomial infection transmission via contact route.

A systematic risk-based strategy to select personal protective equipment for infectious diseases

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Selection of personal protective equipment (PPE) can be systematic and risk-based.

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Potential exposures are compared with sites susceptible to infection.

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Facilitates transparent decision-making about personal protective equipment.

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PPE evaluation includes: donning/doffing/changing, usability, and fit for purpose.

Background

Personal protective equipment (PPE) is a primary strategy to protect health care personnel (HCP) from infectious diseases. When transmission-based PPE ensembles are not appropriate, HCP must recognize the transmission pathway of the disease and anticipate the exposures to select PPE. Because guidance for this process is extremely limited, we proposed a systematic, risk-based approach to the selection and evaluation of PPE ensembles to protect HCP against infectious diseases.

Methods

The approach used in this study included the following 4 steps: (1) job hazard analysis, (2) infectious disease hazard analysis, (3) selection of PPE, and (4) evaluation of selected PPE. Selected PPE should protect HCP from exposure, be usable by HCP, and fit for purpose.

Results

The approach was demonstrated for the activity of intubation of a patient with methicillin-resistant Staphylococcus aureus or Severe Acute Respiratory Syndrome coronavirus. As expected, the approach led to the selection of different ensembles of PPE for these 2 pathogens.

Discussion

A systematic risk-based approach to the selection of PPE will help health care facilities and HCP select PPE when transmission-based precautions are not appropriate. Owing to the complexity of PPE ensemble selection and evaluation, a team with expertise in infectious diseases, occupational health, the health care activity, and related disciplines, such as human factors, should be engaged.

Conclusions

Participation, documentation, and transparency are necessary to ensure the decisions can be communicated, critiqued, and understood by HCP.

Potential for occupational exposures to pathogens during bronchoscopy procedures

Bronchoscopy is classified as an aerosol-generating procedure, but it is unclear what drives the elevated infection risk observed among healthcare personnel performing the procedure. The objective of this study was to characterize pathways through which bronchoscopists may be exposed to infectious agents during bronchoscopy procedures. Aerosol number concentrations (0.2-1 µm aerodynamic diameter) were measured using a P-Trak Ultrafine Particle Counter 8525 and mass concentrations (<10 µm) were measured using a SidePak Personal Aerosol Monitor AM510 near the head of patients during bronchoscopy procedures. Procedure pathway, number of patient coughs, number of suctioning events, number of contacts with different surfaces by the pulmonologist, and the use and doffing of personal protective equipment were recorded by the investigator on a specially designed form. Any pulmonologist performing a bronchoscopy procedure was eligible to participate. A total of 18 procedures were observed. Mean particle number and mass concentrations were not elevated during procedures relative to those measured before or after the procedure, on average, but the concentrations were highly variable, exhibiting high levels periodically. Patients frequently coughed during procedures (median 65 coughs, range: 0-565 coughs), and suctioning was commonly performed (median 6.5 suctioning events, range: 0-42). In all procedures, pulmonologists contacted the patient (mean 22.3 contacts, range: 1-48), bronchoscope (mean 19.4 contacts, range: 1-46), and at least one environmental surface (mean 31.2 contacts, range: 3-62). In the majority of procedures, the participant contacted his or her body or personal protective equipment (PPE), with a mean of 17.3 contacts (range: 4-48). More often than not, the observed PPE doffing practices differed from those recommended. Bronchoscopy procedures were associated with short-term increased ultrafine or respirable aerosol concentrations, and there were opportunities for contact transmission.

Environmental Contact and Self-contact Patterns of Healthcare Workers: Implications for Infection Prevention and Control

BACKGROUND

Respiratory viruses on fomites can be transferred to sites susceptible to infection via contact by hands or other fomites.

METHODS

Care for hospitalized patients with viral respiratory infections was observed in the patient room for 3-hour periods at an acute care academic medical center for over a 2 year period. One trained observer recorded the healthcare activities performed, contacts with fomites, and self-contacts made by healthcare workers (HCWs), while another observer recorded fomite contacts of patients during the encounter using predefined checklists.

RESULTS

The surface contacted by HCWs during the majority of visits was the patient (90%). Environmental surfaces contacted by HCWs frequently during healthcare activities included the tray table (48%), bed surface (41%), bed rail (41%), computer station (37%), and intravenous pole (32%). HCWs touched their own torso and mask in 32% and 29% of the visits, respectively. HCWs' self-contacts differed significantly among HCW job roles, with providers and respiratory therapists contacting themselves significantly more times than nurses and nurse technicians (P < .05). When HCWs performed only 1 care activity, there were significant differences in the number of patient contacts and self-contacts that HCWs made during performance of multiple care activities (P < .05).

CONCLUSIONS

HCWs regularly contact environmental surfaces, patients, and themselves while providing care to patients with infectious diseases, varying among care activities and HCW job roles. These contacts may facilitate the transmission of infection to HCWs and susceptible patients.

Prenatal exposure to nitrate in drinking water and the risk of congenital anomalies

BACKGROUND

Nitrate is a common water contaminant that has been associated with birth defects, although the evidence is limited. The purpose of this study was to examine whether maternal consumption of nitrate through drinking water is associated with an increased risk of congenital anomalies.

METHODS

The study included a total of 348,250 singletons births from the state of Missouri between January 1, 2004 and December 31, 2008. Individual-level birth defect data and maternal and child characteristics were obtained from the Missouri birth defects registry and state vital statistics records. Outcomes were linked with county-specific monthly estimates of the nitrate concentration in finished water, based on data collected for compliance with the Safe Drinking Water Standard. Poisson models were fit to examine the association between nitrate exposure and birth defects. Average nitrate exposure during the first trimester and over 12 months prior to birth were modeled as continuous variables. Sensitivity analyses included restriction of the sample to counties with <20% and <10% private well usage to reduce exposure misclassification as well as limiting the analyses to residents of rural counties only to account for potential confounding by urbanicity.

RESULTS

Estimated water concentrations of nitrate were generally low and below the Environmental Protection Agency's maximum contaminant level of 10 mg/L. Nitrate exposure was associated with a significantly increased risk of limb deficiencies (RR for 1 mg/L (RR1) = 1.26, 95% CI = 1.05, 1.51) in models without well restriction. Nitrate was also weakly associated with an increased risk of congenital heart defects (RR1 = 1.13, 95%CI = 0.93, 1.51) and neural tube defects (RR1 = 1.18, 95%CI = 0.93, 1.51) in models with well restriction (<10%).

CONCLUSION

The positive associations found between nitrate exposure via drinking water and congenital abnormalities are largely consistent with some previous epidemiologic studies. The results of this study should be interpreted with caution given limitations in our ability to estimate exposures and the lack information on some risk factors for congenital abnormalities. Our findings may have serious policy implications given that exposure levels in our study were well below current EPA standards for nitrate in drinking water.

Experience of Chicagoland acute care hospitals in preparing for Ebola virus disease, 2014-2015

During the 2014-2015 Ebola Virus Disease (EVD) outbreak, hospitals in the United States selected personal protective equipment (PPE) and trained healthcare personnel (HCP) in anticipation of receiving EVD patients. To improve future preparations for high-consequence infectious diseases, it was important to understand factors that affected PPE selection and training in the context of the EVD outbreak. Semistructured interviews were conducted with HCP involved with decision-making during EVD preparations at acute care hospitals in the Chicago, IL area to gather information about the PPE selection and training process. HCP who received training were surveyed about elements of training and their perceived impact and overall experience by email invitation. A total of 28 HCP from 15 hospitals were interviewed, and 55 HCP completed the survey. Factors affecting PPE selection included: changing guidance, vendor supply, performance evaluations, and perceived risk and comfort for HCP. Cost did not affect selection. PPE acquisition challenges were mitigated by: sharing within hospital networks, reusing PPE during training, and improvising with existing PPE stock. Selected PPE ensembles were similar across sites. Training included hands-on activities with trained observers, instructional videos, and simulations/drills, which were felt to increase HCP confidence. Many felt refresher training would be helpful. Hands-on training was perceived to be effective, but there is a need to establish the appropriate frequency of refresher training frequency to maintain competence. Lacking confidence in the CDC guidance, interviewed trainers described turning to other sources of information and developing independent PPE evaluation and selection. Response to emerging and/or high consequence infectious diseases would be enhanced by transparent, risk-based guidance for PPE selection and training that addresses protection level, ease of use, ensembles, and availability.

Personal protective equipment doffing practices of healthcare workers

During the doffing of personal protective equipment (PPE), pathogens can be transferred from the PPE to the bodies of healthcare workers (HCWs), putting HCWs and patients at risk of exposure and infection. PPE doffing practices of HCWs who cared for patients with viral respiratory infections were observed at an acute care hospital from March 2017 to April 2018. A trained observer recorded doffing performance of HCWs inside the patient rooms using a pre-defined checklist based on the Centers for Disease Control and Prevention (CDC) guideline. Doffing practices were observed 162 times during care of 52 patients infected with respiratory viral pathogens. Out of the 52 patients, 30 were in droplet and contact isolation, 21 were in droplet isolation, and 1 was in contact isolation. Overall, 90% of observed doffing was incorrect, with respect to the doffing sequence, doffing technique, or use of appropriate PPE. Common errors were doffing gown from the front, removing face shield of the mask, and touching potentially contaminated surfaces and PPE during doffing. Deviations from the recommended PPE doffing protocol are common and can increase potential for contamination of the HCW's clothing or skin after providing care. There is a clear need to change the approach used to training HCWs in PPE doffing practices.

Bibliometric analysis of cardiometabolic disorders studies involving NO2, PM2.5 and noise exposure

BACKGROUND

This study uses bibliometric analysis to describe the state of research about the association of NO2, PM2.5 and noise exposures - three traffic-related pollutants - with cardiometabolic disorders.

METHODS

We retrieved references published 1994-2017 from Scopus and classified references with respect to exposure, health outcome and study design using index keywords. Temporal trend, top cited references, used index keywords and the number of hypothesis testing and non-hypothesis testing study design for each group were identified.

RESULTS

Results show PM2.5 is the most frequently studied exposure (47%), followed by both NO2 and PM2.5 exposure (29%). Only 3% of references considered multiple exposures between NO2 and/or PM2.5 and noise, and these were published after 2008. While we observed a growing trend in studies with NO2 and/or PM2.5 and noise and diabetes in the last decade, there is a diminishing trend in studies with noise and diabetes. Different patterns of study designs were found through H/NH ratio, the number of references classified as having a hypothesis (H)-testing design relative to the number of references classified as having a non-hypothesis (NH)-testing design. Studies with NO2 and/or PM2.5 exposure are more likely to have a H-testing design, while those with noise exposure are more likely to have a NH-testing design, such as cross-sectional study design.

CONCLUSIONS

We conclude with three themes about research trends. First, the study of simultaneous exposures to multiple pollutants is a current trend, and likely to continue. Second, the association between traffic-related pollutants and diabetes and metabolic symptoms is an area for growth in research. Third, the transition to the use of H-testing study designs to explore associations between noise and cardiometabolic outcomes may be supported by improved understanding of the mechanism of action, and/or improvements to the accuracy and precision of air pollution and noise exposure assessments for environmental health research.

Environmental and Personal Protective Equipment Contamination during Simulated Healthcare Activities

Providing care to patients with an infectious disease can result in the exposure of healthcare workers (HCWs) to pathogen-containing bodily fluids. We performed a series of experiments to characterize the magnitude of environmental contamination—in air, on surfaces and on participants—associated with seven common healthcare activities. The seven activities studied were bathing, central venous access, intravenous access, intubation, physical examination, suctioning and vital signs assessment. HCWs with experience in one or more activities were recruited to participate and performed one to two activities in the laboratory using task trainers that contained or were contaminated with fluorescein-containing simulated bodily fluid. Fluorescein was quantitatively measured in the air and on seven environmental surfaces. Fluorescein was quantitatively and qualitatively measured on the personal protective equipment (PPE) worn by participants. A total of 39 participants performed 74 experiments, involving 10–12 experimental trials for each healthcare activity. Healthcare activities resulted in diverse patterns and levels of contamination in the environment and on PPE that are consistent with the nature of the activity. Glove and gown contamination were ubiquitous, affirming the value of wearing these pieces of PPE to protect HCW’s clothing and skin. Though intubation and suctioning are considered aerosol-generating procedures, fluorescein was detected less frequently in air and at lower levels on face shields and facemasks than other activities, which suggests that the definition of aerosol-generating procedure may need to be revised. Face shields may protect the face and facemask from splashes and sprays of bodily fluids and should be used for more healthcare activities.