Efficacy of an ambulance ventilation system in reducing EMS worker exposure to airborne particles from a patient cough aerosol simulator

COVID-19 deaths in dental occupations and other healthcare occupations among U.S. decedents in 2020

BACKGROUND

Early studies during the COVID-19 pandemic suggested dental occupations were among the highest risk for exposure to SARs-CoV-2 because of multiple factors increasing exposure, including close proximity to unmasked patients and performance of aerosol-generating procedures. However, to date, few studies have investigated COVID-19 deaths in United States dental occupations, and compared COVID-19 deaths among healthcare occupations.

METHODS

We analyzed 2020 mortality data collected by the National Center for Health Statistics' National Vital Statistics System. Multivariable logistic regression was used to generate odds ratios (ORs) and 95% confidence intervals for COVID-19 as the underlying cause of death in relation to occupation in working-age decedents (≤65 years), after adjusting for age, sex, race/ethnicity, education, and medical conditions associated with severe COVID-19.

RESULTS

Dental occupations did not have significantly higher risk for COVID-19 death when compared to all other occupations combined. Among healthcare occupations with frequent, direct patient- or client interactions, LPNs and LVNs, and speech and language pathologists had significantly elevated adjusted ORs for COVID-19 death when compared to dentists, dental hygienists, or dental assistants. Similarly, nurse practitioners had significantly higher ORs for COVID-19 mortality than dentists or dental hygienists, and approached significance when compared to dental assistants. Conversely, massage therapists and other health diagnosing and treating practitioners had significantly lower adjusted ORs for COVID-19 death compared with dental occupations.

CONCLUSION

Our study highlights potential differences in work-related transmission of SARs-CoV-2 and subsequent COVID-19 deaths in healthcare occupations, and furthers a previously limited understanding of COVID-19 deaths in healthcare occupations in 2020, before COVID-19 vaccine availability. Our results indicate that dental occupations were not among the highest, nor lowest risk, healthcare occupations for COVID-19 deaths in 2020, despite their known risks of direct exposure.

Exploring Disparities in Self-Reported Mental Health Symptoms Across Professional Categories in Spain's Emergency Medical Services: A Nationwide Cross-Sectional Study

OBJECTIVE

This study aimed to analyze stress, anxiety, depression, and self-efficacy levels among Spanish out-of-hospital emergency medical professionals from February 1, 2021, to April 30, 2021.

METHODS

A nationwide survey was completed by 1666 Emergency Medical Services (EMS) workers. The Depression, Anxiety, and Stress Scale (DASS-21) and the General Self-Efficacy Scale (GSE) were used. Data analysis used chi-squared, análisis of variance (ANOVA), and logistic regressions.

RESULTS

The sample comprised 833 (50%) men, with an average age of 44.3 ± 9.9 y (range: 19-67 y). Occupational distribution included 453 (27.2%) physicians, 474 (28.4%) nurses, and 739 (44.4%) emergency medical technicians (EMTs). EMTs exhibited higher odds of severe or extremely severe depression compared with physicians (odds ratio [OR]: 1.569; 95% confidenceinterval [95% CI]: 1.213-2.030) and nurses (OR: 1.561; 95% CI: 1.211-2.012). EMTs also displayed higher probabilities of severe or extremely severe anxiety compared with nurses (OR: 1.944; 95% CI: 1.529-2.701). Furthermore, EMTs demonstrated elevated probabilities of severe or extremely severe stress compared with physicians (OR: 1.387; 95% CI: 1.088-1.770). However, no significant differences were found in self-efficacy, with a median value of 73 [20].

CONCLUSIONS

Out-of-hospital EMS workers experienced mental health challenges, showing varying levels of depression, stress, and anxiety across different occupational groups. EMTs were particularly affected.

Use of a Negative Pressure Containment Pod Within Ambulance-Workspace During Pandemic Response

Emergency medical service (EMS) providers have a higher potential exposure to infectious agents than the general public (Nguyen et al., 2020, "Risk of COVID-19 Among Frontline Healthcare Workers and the General Community: A Prospective Cohort Study," Lancet Pub. Health, 5(9), pp. e475-e483; Brown et al., 2021, "Risk for Acquiring Coronavirus Disease Illness Among Emergency Medical Service Personnel Exposed to Aerosol-Generating Procedures," Emer. Infect. Disease J., 27(9), p. 2340). The use of protective equipment may reduce, but does not eliminate their risk of becoming infected as a result of these exposures. Prehospital environments have a high risk of disease transmission exposing EMS providers to bioaerosols and droplets from infectious patients. Field intubation procedures may be performed causing the generation of bioaerosols, thereby increasing the exposure of EMS workers to pathogens. Additionally, ambulances have a reduced volume compared to a hospital treatment space, often without an air filtration system, and no control mechanism to reduce exposure. This study evaluated a containment plus filtration intervention for reducing aerosol concentrations in the patient module of an ambulance. Aerosol concentration measurements were taken in an unoccupied research ambulance at National Institute for Occupational Safety and Health (NIOSH) Cincinnati using a tracer aerosol and optical particle counters (OPCs). The evaluated filtration intervention was a containment pod with a high efficiency particulate air (HEPA)-filtered extraction system that was developed and tested based on its ability to contain, capture, and remove aerosols during the intubation procedure. Three conditions were tested (1) baseline (without intervention), (2) containment pod with HEPA-1, and (3) containment pod with HEPA-2. The containment pod with HEPA-filtered extraction intervention provided containment of 95% of the total generated particle concentration during aerosol generation relative to the baseline condition, followed by rapid air cleaning within the containment pod. This intervention can help reduce aerosol concentrations within ambulance patient modules while performing aerosol-generating procedures.

The measuring aerosol spreading during countermeasures (MASC) study presents an automated system to investigate face mask efficacy and other aerosol countermeasures in varying environments

The COVID-19 pandemic exemplified the importance of research on personal protective equipment. In specific, understanding how effective surgical masks or particulate filter respirators are at reducing the transmission of infectious diseases has suddenly become one of the most pressing issues for legislators, regulators, and everyday life. However, there was a lack of available scientific platforms to assess this issue. Therefore, we designed and built a system entitled MASC: measuring aerosol spreading during countermeasures. This platform allows the simulation of various everyday situations and evaluation of the efficacy of masks and respirators in reducing the amount of inhaled particulate matter from the air. Furthermore, MASC can be used to investigate how aerosols propagate in closed spaces, such as offices or classrooms. It can be used to generate aerosols on command and control the room temperature, humidity, and wind speed. Up to four laser aerosol spectrometers can be read simultaneously, and a camera can automatically take pictures to evaluate the efficacy of countermeasures to prevent the spread of aerosols. The aerosol generation, measurement periods, and the number of repetitions for an experiment can be configured digitally and are executed by a computer automatically. A website displays the data in real time and allows monitoring of the experiment. Upon completion, statistical values are calculated automatically to accelerate the evaluation of the gathered data. Codes and technical drawings in this present methodology publication are open source and can be used by the scientific community to establish similar systems.

Investigation of the Optimal Operating Position of an Air Cleaner in Terms of Indoor Air Quality in a Four-Bed Hospital Ward

The use of air cleaners indoors has increased with the increase in indoor activities driven by the COVID-19 outbreak. In this study, the indoor air quality was determined at the location of each patient's respirator in a four-bed hospital ward equipped with a ventilation system and curtains, by varying the position of one air cleaner. By operating the air cleaner alone without the ventilation system, it was confirmed that it is better to place the air cleaner close to the center of the ward, regardless of whether curtains are used. It was further identified that the farther away the air cleaner is from the center, the worse the age of air could be, compared to the case of operating it in the center. Moreover, the situation where the ventilation system and air cleaner were operated simultaneously in the hospital ward was considered. It was discovered that operating the air cleaner close to the ventilation inlets in the absence of curtains helps to improve the indoor air quality. Furthermore, it was found that the age of the air is generally low near the location where the air cleaner is operated in the presence of curtains. Selecting an optimal position for the air cleaner can improve the air quality at the location of each bed in a four-bed hospital ward.

Reduction of exposure to simulated respiratory aerosols using ventilation, physical distancing, and universal masking

To limit community spread of SARS-CoV-2, CDC recommends universal masking indoors, maintaining 1.8 m of physical distancing, adequate ventilation, and avoiding crowded indoor spaces. Several studies have examined the independent influence of each control strategy in mitigating transmission in isolation, yet controls are often implemented concomitantly within an indoor environment. To address the influence of physical distancing, universal masking, and ventilation on very fine respiratory droplets and aerosol particle exposure, a simulator that coughed and exhaled aerosols (the source) and a second breathing simulator (the recipient) were placed in an exposure chamber. When controlling for the other two mitigation strategies, universal masking with 3-ply cotton masks reduced exposure to 0.3-3 µm coughed and exhaled aerosol particles by >77% compared to unmasked tests, whereas physical distancing (0.9 or 1.8 m) significantly changed exposure to cough but not exhaled aerosols. The effectiveness of ventilation depended upon the respiratory activity, that is, coughing or breathing, as well as the duration of exposure time. Our results demonstrate that a layered mitigation strategy approach of administrative and engineering controls can reduce personal inhalation exposure to potentially infectious very fine respiratory droplets and aerosol particles within an indoor environment.

Laboratory study of physical barrier efficiency for worker protection against SARS-CoV-2 while standing or sitting

Transparent barriers were installed as a response to the SARS-COV-2 pandemic in many customer-facing industries. Transparent barriers are an engineering control that intercept particles traveling between customers and workers. Information on the effectiveness of these barriers against aerosols is limited. In this study, a cough simulator was used to represent a cough from a customer. Two optical particle counters were used (one on each side of the barrier, labeled customer and worker) to determine the number of particles that migrated around a transparent barrier. Ten configurations were tested with six replicates for both sitting and standing scenarios, representing nail salons and grocery stores, respectively. Barrier efficiency was calculated using a ratio of the particle count results (customer/worker). Barriers had better efficiency (up to 93%) when its top was 9 to 39 cm above cough height and its width was at least 91 cm. Barriers that extended 91 cm above table height for both scenarios blocked 71% or more of the particles between 0.35-0.725 μm and 68% for particles between 1 to 3 μm. A barrier that blocked an initial cough was effective at reducing particle counts. While the width of the barriers was not as significant as the height in determining barrier efficiency it is important that a barrier be placed where interactions between customers and workers are most frequent. Bystander exposure was not taken into consideration along with other limitations.

What We Are Learning from COVID-19 for Respiratory Protection: Contemporary and Emerging Issues

Infectious respiratory diseases such as the current COVID-19 have caused public health crises and interfered with social activity. Given the complexity of these novel infectious diseases, their dynamic nature, along with rapid changes in social and occupational environments, technology, and means of interpersonal interaction, respiratory protective devices (RPDs) play a crucial role in controlling infection, particularly for viruses like SARS-CoV-2 that have a high transmission rate, strong viability, multiple infection routes and mechanisms, and emerging new variants that could reduce the efficacy of existing vaccines. Evidence of asymptomatic and pre-symptomatic transmissions further highlights the importance of a universal adoption of RPDs. RPDs have substantially improved over the past 100 years due to advances in technology, materials, and medical knowledge. However, several issues still need to be addressed such as engineering performance, comfort, testing standards, compliance monitoring, and regulations, especially considering the recent emergence of pathogens with novel transmission characteristics. In this review, we summarize existing knowledge and understanding on respiratory infectious diseases and their protection, discuss the emerging issues that influence the resulting protective and comfort performance of the RPDs, and provide insights in the identified knowledge gaps and future directions with diverse perspectives.

Psychological Impact of the COVID-19 Pandemic on Out-of-Hospital Health Professionals: A Living Systematic Review

Health professionals (HPs), especially those working in the front line, have been one of the groups most affected by the COVID-19 pandemic. The objective of this study is to identify the best available scientific evidence on the impact of the COVID-19 pandemic on the mental health of out-of-hospital HPs in terms of stress, anxiety, depression, and self-efficacy. A living systematic review of the literature was designed, consulting the electronic online versions of the CINHAL, Cochrane Library, Cuiden, IBECS, JBI, LILACS, Medline PyscoDoc, PsycoINFO, Scopus, and Web of Science databases in November 2021. Original research was selected, published in either English, Spanish, French, Italian, or Portuguese. In total, 2082 publications were identified, of which 16 were included in this review. The mental health of out-of-hospital HPs was affected. Being a woman or having direct contact with patients showing suspicious signs of COVID-19 or confirmed cases were the factors related to a greater risk of developing high levels of stress and anxiety; in the case of depressive symptoms, it was having a clinical history of illnesses that could weaken their defenses against infection. Stopping unpleasant emotions and thoughts was the coping strategy most frequently used by these HPs.

Attitudes and stressors related to the SARS-CoV-2 pandemic among emergency medical services workers in Germany: a cross-sectional study

BACKGROUND

The aim was to investigate attitudes and stressors related to the SARS-CoV-2 outbreak among emergency medical services (EMS) workers in Germany. We further aimed to detect possible changes within a 5-week period and potential determinants of attitudes and stressors.

METHODS

We conducted two cross-sectional studies using an online questionnaire in early April 2020 (i.e., the first peak of the SARS-CoV-2 outbreak in Germany) and five weeks later. The study instrument comprised sociodemographic items, self-devised items on pandemic-related attitudes, stressors and work outcomes, and established instruments assessing depressive symptoms and symptoms of anxiety. Logistic regression was performed to identify possible determinants.

RESULTS

Data of 1537 participants was included in the analysis (April: n = 1124, May: n = 413, 83.1% male, median age 32). Most participants agreed that their personal risk of infection was higher compared to the general population (April: 87.0% agreement, May: 78.9%). The greatest stressor was uncertainty about the pandemic's temporal scope (82.0 and 80.9%, respectively). Most participants (69.9, 79.7%) felt sufficiently prepared for the pandemic and only few felt burdened by their financial situation (18.8, 13.3%). Agreement to all stressors decreased from April to May except related to the childcare situation. Regression analysis identified subgroups to be burdened more frequently such as older employees, those with SARS-CoV-2 cases among their colleagues, and those with lower paramedic training levels.

CONCLUSIONS

We identified key SARS-CoV-2-related stressors whose levels generally decreased within a 5-week period. Our results indicate that EMS workers are less affected by existential fears and rather worry about their personal infection risk.

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.

Efficacy of face masks, neck gaiters and face shields for reducing the expulsion of simulated cough-generated aerosols

Face masks are recommended to reduce community transmission of SARS-CoV-2. One of the primary benefits of face masks and other coverings is as source control devices to reduce the expulsion of respiratory aerosols during coughing, breathing, and speaking. Face shields and neck gaiters have been proposed as an alternative to face masks, but information about face shields and neck gaiters as source control devices is limited. We used a cough aerosol simulator with a pliable skin headform to propel small aerosol particles (0 to 7 μm) into different face coverings. An N95 respirator blocked 99% (standard deviation (SD) 0.3%) of the cough aerosol, a medical grade procedure mask blocked 59% (SD 6.9%), a 3-ply cotton cloth face mask blocked 51% (SD 7.7%), and a polyester neck gaiter blocked 47% (SD 7.5%) as a single layer and 60% (SD 7.2%) when folded into a double layer. In contrast, the face shield blocked 2% (SD 15.3%) of the cough aerosol. Our results suggest that face masks and neck gaiters are preferable to face shields as source control devices for cough aerosols.

Efficacy of face masks, neck gaiters and face shields for reducing the expulsion of simulated cough-generated aerosols

Face masks are recommended to reduce community transmission of SARS-CoV-2. One of the primary benefits of face masks and other coverings is as source control devices to reduce the expulsion of respiratory aerosols during coughing, breathing, and speaking. Face shields and neck gaiters have been proposed as an alternative to face masks, but information about face shields and neck gaiters as source control devices is limited. We used a cough aerosol simulator with a pliable skin headform to propel small aerosol particles (0 to 7 μm) into different face coverings. An N95 respirator blocked 99% (standard deviation (SD) 0.3%) of the cough aerosol, a medical grade procedure mask blocked 59% (SD 6.9%), a 3-ply cotton cloth face mask blocked 51% (SD 7.7%), and a polyester neck gaiter blocked 47% (SD 7.5%) as a single layer and 60% (SD 7.2%) when folded into a double layer. In contrast, the face shield blocked 2% (SD 15.3%) of the cough aerosol. Our results suggest that face masks and neck gaiters are preferable to face shields as source control devices for cough aerosols.

Design and evaluation of a portable negative pressure hood with HEPA filtration to protect health care workers treating patients with transmissible respiratory infections

Background

To mitigate potential exposure of healthcare workers (HCWs) to SARS-CoV-2 via aerosol routes, we have developed a portable hood which not only creates a barrier between HCW and patient, but also utilizes negative pressure with filtration of aerosols by a high-efficiency particulate air filter.

Material and Methods

The hood has iris-port openings for access to the patient, and an opening large enough for a patient's head and upper torso. The top of the hood is a high-efficiency particulate air filter connected to a blower to apply negative pressure. We determined the aerosol penetration from outside to inside in laboratory experiments.

Results

The penetration of particles from within the hood to the breathing zones of HCWs outside the hood was near 10^-4 (0.01%) in the 200-400 nm size range, and near 10⁻³ (0.1%) for smaller particles. Penetration values for particles in the 500 nm-5 μm range were below 10⁻² (1%). Fluorometric analysis of deposited fluorescein particles on the personal protective equipment of an HCW revealed that negative pressure reduces particle deposition both outside and inside the hood.

Conclusions

We find that negative pressure hoods can be effective controls to mitigate aerosol exposure to HCWs, while simultaneously allowing access to patients.

Improved Testing and Design of Intubation Boxes During the COVID-19 Pandemic

Study objective

Throughout the coronavirus disease 2019 pandemic, many emergency departments have been using passive protective enclosures (“intubation boxes”) during intubation. The effectiveness of these enclosures remains uncertain. We sought to quantify their ability to contain aerosols using industry standard test protocols.

Methods

We tested a commercially available passive protective enclosure representing the most common design and compared this with a modified enclosure that incorporated a vacuum system for active air filtration during simulated intubations and negative-pressure isolation. We evaluated the enclosures by using the same 3 tests air filtration experts use to certify class I biosafety cabinets: visual smoke pattern analysis using neutrally buoyant smoke, aerosol leak testing using a test aerosol that mimics the size of virus-containing particulates, and air velocity measurements.

Results

Qualitative evaluation revealed smoke escaping from all passive enclosure openings. Aerosol leak testing demonstrated elevated particle concentrations outside the enclosure during simulated intubations. In contrast, vacuum-filter-equipped enclosures fully contained the visible smoke and test aerosol to standards consistent with class I biosafety cabinet certification.

Conclusion

Passive enclosures for intubation failed to contain aerosols, but the addition of a vacuum and active air filtration reduced aerosol spread during simulated intubation and patient isolation.

A COVID-19 Airway Management Innovation with Pragmatic Efficacy Evaluation: The Patient Particle Containment Chamber

The unique resource constraints, urgency, and virulence of the coronavirus disease 2019 pandemic has sparked immense innovation in the development of barrier devices to protect healthcare providers from infectious airborne particles generated by patients during airway management interventions. Of the existing devices, all have shortcomings which render them ineffective and impractical in out-of-hospital environments. Therefore, we propose a new design for such a device, along with a pragmatic evaluation of its efficacy. Must-have criteria for the device included: reduction of aerosol transmission by at least 90% as measured by pragmatic testing; construction from readily available, inexpensive materials; easy to clean; and compatibility with common EMS stretchers. The Patient Particle Containment Chamber (PPCC) consists of a standard shower liner draped over a modified octagonal PVC pipe frame and secured with binder clips. 3D printed sleeve portals were used to secure plastic sleeves to the shower liner wall. A weighted tube sealed the exterior base of the chamber with the contours of the patient's body and stretcher. Upon testing, the PPCC contained 99% of spray-paint particles sprayed over a 90s period. Overall, the PPCC provides a compact, affordable option that can be used in both the in-hospital and out-of-hospital environments.