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in category occupational and environmental health

197 results found. For more information, click each entry to expand.

1: Assessment of Fabric Masks as Alternatives to Standard Surgical Masks in Terms of Particle Filtration Efficiency
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Posted 22 Apr 2020

Assessment of Fabric Masks as Alternatives to Standard Surgical Masks in Terms of Particle Filtration Efficiency
130,890 downloads medRxiv occupational and environmental health

Amy V Mueller, Matthew J. Eden, Jessica J. Oakes, Chiara Bellini, Loretta A Fernandez

In response to the COVID-19 pandemic, cloth masks are being used to control the spread of virus, but the efficacy of these loose-fitting masks is not well known. Here, tools and methods typically used to assess tight-fitting respirators were modified to quantify the efficacy of community- and commercially-produced fabric masks as PPE. Two particle counters concurrently sample ambient air and air inside the masks; mask performance is evaluated by mean particle removal efficiency and statistical variability when worn as designed and with a nylon overlayer, to independently assess fit and material. Worn as designed both commercial surgical masks and cloth masks had widely varying effectiveness (53-75% and 28-90% filtration efficiency, respectively). Most surgical-style masks improved with the nylon overlayer, indicating poor fit. This rapid testing method uses widely available hardware, requires only a few calculations from collected data, and provides both a holistic and aspect-wise evaluation of mask performance.

2: UV Sterilization of Personal Protective Equipment with Idle Laboratory Biosafety Cabinets During the Covid-19 Pandemic
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Posted 27 Mar 2020

UV Sterilization of Personal Protective Equipment with Idle Laboratory Biosafety Cabinets During the Covid-19 Pandemic
36,307 downloads medRxiv occupational and environmental health

Davis T Weaver, Benjamin D. McElvany, Vishhvaan Gopalakrishnan, Kyle J. Card, Dena Crozier, Andrew Dhawan, Mina N. Dinh, Emily Dolson, Nathan Farrokhian, Masahiro Hitomi, Emily Ho, Tanush Jagdish, Eshan S King, Nikhil Krishnan, Gleb Kuzmin, Ju Li, Jeff Maltas, Jinhan Mo, Julia Pelesko, Jessica A Scarborough, Geoff Sedor, Enze Tian, Gary C. An, Sean A. Diehl, Jacob G Scott

Personal protective equipment (PPE), including surgical masks and N95 respirators, is crucially important to the safety of both patients and medical personnel, particularly in the event of infectious pandemics. As the incidence of Coronavirus Disease (COVID-19) is increasing exponentially in the United States and worldwide, healthcare provider demand for these necessities is currently outpacing supply. As such, strategies to safely expand the lifespan of the supply of medical equipment are critically important. In the recent days, weeks, and months, in the midst of the current pandemic, there has been a concerted effort to identify viable ways to conserve Personal Protective Equipment, including sterilization after use. Some hospitals have already begun using UV-C light to sterilize N95 respirators, but many lack the space or equipment to implement existing protocols. In this study, we outline a procedure by which N95 respirators may be sterilized using ultraviolet (UV) radiation in biosafety cabinets (BSCs), a common element of many academic, public health, and hospital laboratories. The primary obstacle to this approach is the possibility the UV radiation levels vary within BSCs. To account for this potential variation in dosing across the base of the BSC, we tested the UV-C radiation in two randomly chosen idle BSCs in our research institute and observed a maximum ratio between the minimum and maximum recorded intensities within a given BSC to be 1.98. Based on these values, we calculated that an N95 mask placed within a BSC with a manufacturers reported fluence of 100 W cm-2 should be effectively sanitized for reuse after approximately 15-20 minutes per side. Our results provide support to healthcare organizations looking for alternative methods to extend their reserves of PPE. It is our hope that with an easily implemented strategy, as we have presented here, idle BSCs can be utilized to alleviate the PPE shortage by providing a way to sterilize PPE to allow safe daily re-use. This should be tested on a larger scale, and confirmed in a virology laboratory before adoption, though we contend that in extremis, this method would be preferred compared to re-use without sterilization. DISCLAIMERThis article does not represent the official recommendation of the Cleveland Clinic or Case Western Reserve University School of Medicine, nor has it yet been peer reviewed. We are releasing it early, pre-peer review, to allow for quick dissemination/vetting by the scientific/clinical community given the necessity for rapid conservation of personal protective equipment (PPE) during this dire global situation. We welcome feedback from the community.

3: Presence of SARS-Coronavirus-2 in sewage
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Posted 30 Mar 2020

Presence of SARS-Coronavirus-2 in sewage
34,645 downloads medRxiv occupational and environmental health

Gertjan Medema, Leo Heijnen, Goffe Elsinga, Ronald Italiaander, Anke Brouwer

In the current COVID-19 pandemic, a significant proportion of cases shed SARS-Coronavirus-2 (SARS-CoV-2) with their faeces. To determine if SARS-CoV-2 is present in sewage during the emergence of COVID-19 in the Netherlands, sewage samples of 7 cities and the airport were tested using RT-PCR against three fragments of the nucleocapsid protein gene (N1-3) and one fragment of the envelope protein gene (E). No SARS-CoV-2 was detected in samples of February 6, three weeks before the first case was reported in the Netherlands on February 27. On March 5, the N1 fragment was detected in sewage of five sites. On March 15/16, the N1 fragment was detected in sewage of six sites, and the N3 and E fragment were detected at 5 and 4 sites respectively. This is the first report of detection of SARS-CoV-2 in sewage. The detection of the virus in sewage, even when the COVID-19 prevalence is low, indicates that sewage surveillance could be a sensitive tool to monitor the circulation of the virus in the population.

4: Excess mortality associated with the COVID-19 pandemic among Californians 18-65 years of age, by occupational sector and occupation: March through October 2020
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Posted 22 Jan 2021

Excess mortality associated with the COVID-19 pandemic among Californians 18-65 years of age, by occupational sector and occupation: March through October 2020
30,018 downloads medRxiv occupational and environmental health

Yea-Hung Chen, Maria Glymour, Alicia Riley, John Balmes, Kate Duchowny, Robert Harrison, Ellicott Matthay, Kirsten Bibbins-Domingo

Background Though SARS-CoV-2 outbreaks have been documented in occupational settings and though there is speculation that essential workers face heightened risks for COVID-19, occupational differences in excess mortality have, to date, not been examined. Such information could point to opportunities for intervention, such as workplace modifications and prioritization of vaccine distribution. Methods and findings Using death records from the California Department of Public Health, we estimated excess mortality among Californians 18--65 years of age by occupational sector and occupation, with additional stratification of the sector analysis by race/ethnicity. During the COVID-19 pandemic, working age adults experienced a 22% increase in mortality compared to historical periods. Relative excess mortality was highest in food/agriculture workers (39% increase), transportation/logistics workers (28% increase), facilities (27%) and manufacturing workers (23% increase). Latino Californians experienced a 36% increase in mortality, with a 59% increase among Latino food/agriculture workers. Black Californians experienced a 28% increase in mortality, with a 36% increase for Black retail workers. Asian Californians experienced an 18% increase, with a 40% increase among Asian healthcare workers. Excess mortality among White working-age Californians increased by 6%, with a 16% increase among White food/agriculture workers. Conclusions Certain occupational sectors have been associated with high excess mortality during the pandemic, particularly among racial and ethnic groups also disproportionately affected by COVID-19. In-person essential work is a likely venue of transmission of coronavirus infection and must be addressed through strict enforcement of health orders in workplace settings and protection of in-person workers. Vaccine distribution prioritizing in-person essential workers will be important for reducing excess COVID mortality.

5: ASSESSMENT OF WORKERS PERSONAL VULNERABILITY TO COVID-19 USING COVID-AGE
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Posted 25 May 2020

ASSESSMENT OF WORKERS PERSONAL VULNERABILITY TO COVID-19 USING COVID-AGE
12,741 downloads medRxiv occupational and environmental health

David Coggon, Peter Croft, Paul Cullinan, Anthony Williams

Decisions on fitness for employment that entails a risk of contracting Covid-19 require an assessment of the workers personal vulnerability should infection occur. Using recently published UK data, we have developed a risk model that provides estimates of personal vulnerability to Covid-19 according to sex, age, ethnicity, and various comorbidities. Vulnerability from each risk factor is quantified in terms of its equivalence to added years of age. Addition of the impact from each risk factor to an individuals true age generates their Covid-age, a summary measure representing the age of a healthy UK white male with equivalent vulnerability. We discuss important limitations of the model, including current scientific uncertainties and limitations on generalisability beyond the UK setting and its use beyond informing assessments of individual vulnerability in the workplace. As new evidence becomes available, some of these limitations can be addressed. The model does not remove the need for clinical judgement or for other important considerations when managing occupational risks from Covid-19.

6: Pneumask: Modified Full-Face Snorkel Masks as Reusable Personal Protective Equipment for Hospital Personnel
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Posted 29 Apr 2020

Pneumask: Modified Full-Face Snorkel Masks as Reusable Personal Protective Equipment for Hospital Personnel
10,402 downloads medRxiv occupational and environmental health

Laurel Kroo, Anesta Kothari, Melanie Hannebelle, George Herring, Thibaut Pollina, Ray Chang MD, Samhita P. Banavar, Elliot Flaum, Hazel Soto-Montoya, Hongquan Li, Kyle Combes, Emma Pan, Khang Vu, Kelly Yen, James Dale, Patrick Kolbay, Simon Ellgas, Rebecca Konte, Rozhin Hajian, Grace Zhong, Noah Jacobs, Amit Jain, Filip Kober, Gerry Ayala, Quentin Allinne, Nicholas Cucinelli, Dave Kasper, Luca Borroni, Patrick Gerber, Ross Venook, Peter Baek MD, Nitin Arora M.D., Philip Wagner MD, Roberto Miki MD, Jocelyne Kohn MD, David Kohn Bitran MD, John Pearson MD, Cristian Muniz Herrera MD, Manu Prakash

Here we adapt and evaluate a full-face snorkel mask for use as personal protective equipment (PPE) for health care workers, who lack appropriate alternatives during the COVID-19 crisis in the spring of 2020. The design (referred to as Pneumask) consists of a custom snorkel-specific adapter that couples the snorkel-port of the mask to a rated filter (either a medical-grade ventilator inline filter or an industrial filter). This design has been tested for the sealing capability of the mask, filter performance, CO2 buildup and clinical usability. These tests found the Pneumask capable of forming a seal that exceeds the standards required for half-face respirators or N95 respirators. Filter testing indicates a range of options with varying performance depending on the quality of filter selected, but with typical filter performance exceeding or comparable to the N95 standard. CO2 buildup was found to be roughly equivalent to levels found in half-face elastomeric respirators in literature. Clinical usability tests indicate sufficient visibility and, while speaking is somewhat muffled, this can be addressed via amplification (Bluetooth voice relay to cell phone speakers through an app) in noisy environments. We present guidance on the assembly, usage (donning and doffing) and decontamination protocols. The benefit of the Pneumask as PPE is that it is reusable for longer periods than typical disposable N95 respirators, as the snorkel mask can withstand rigorous decontamination protocols (that are standard to regular elastomeric respirators). With the dire worldwide shortage of PPE for medical personnel, our conclusions on the performance and efficacy of Pneumask as an N95-alternative technology are cautiously optimistic.

7: Knowledge, Attitude and Practice among Healthcare Professionals regarding COVID-19: A cross-sectional survey from Pakistan
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Posted 17 Apr 2020

Knowledge, Attitude and Practice among Healthcare Professionals regarding COVID-19: A cross-sectional survey from Pakistan
7,690 downloads medRxiv occupational and environmental health

Muhammad Saqlain, Muhammad Muddasir Munir, Saif Ur Rehman, Aqsa Gulzar, Sahar Naz, Zaheer Ahmed, Azhar Hussain Tahir, Muhammad Mashhood

Coronavirus disease (COVID-19) is a highly transmittable infection and Pakistan faces sudden hike in number of positive cases including number of healthcare professionals (HCPs) also acquired infection. Knowledge, attitude, and practice survey provides a suitable format to evaluate existing programs and to identify effective strategies for behavior change in society. Therefore, the aim of study is to assess knowledge, attitude and practice among HCPs in Pakistan regarding COVID-19. An online survey-based study was conducted among healthcare professionals including physicians, pharmacists and nurses. A self-administered validated (Cronbach alpha=0.077) questionnaire comprised of five sections (Demographics, Knowledge, attitude, practice and perceived barriers) were used for data collection. Of 414 participants, 29.98% (n=120) physicians, 46.65% (n= 189) pharmacists and 25.36% (n= 105%) nurses. Most commonly utilized information source was social media. Findings showed HCPs have good knowledge (93.2%, n=386), positive attitude (Mean 8.43, SD:1.78) and good practice (88.7%, n=367) regarding COVID-19. HCPs perceived that overcrowding in emergency room (52.9%, n=219), limited infection control material (50.7%, n=210) and poor knowledge regarding transmission (40.6%, n=168) of COVID-19 are the major barriers in infection control practice. Binary logistic regression analysis demonstrated that HCPs of age group 40-49 years (OR: 1.419, 95%CI: (0.14-4.78, P=0.041) have higher odds of good knowledge. Similarly, age group of 31-39 years (OR: 1.377, 95% CI: 0.14-2.04, P=0.05), experience of more than 5 years (OR: 10.71, 95% CI: 2.83-40.75, P<0.001), and pharmacist job (OR: 2.247, 95% CI: 1.11-4.55, P=0.025) were the substantial determinants of good practice regarding COVID-19. HCPs in Pakistan have good knowledge, yet, there are areas where gaps in knowledge and practice was observed. To effectively control infection spread, well-structured training programs must be launched by government targeting all kinds of HCPs to raise their existed knowledge.

8: Can N95 respirators be reused after disinfection? And for how many times?
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Posted 07 Apr 2020

Can N95 respirators be reused after disinfection? And for how many times?
7,610 downloads medRxiv occupational and environmental health

Lei Liao, Wang Xiao, Mervin Zhao, Xuanze Yu, Haotian Wang, Qiqi Wang, Steven Chu, Yi Cui

The Coronavirus Disease 2019 (COVID-19) pandemic has led to a major shortage of N95 respirators, which protect healthcare professionals and the public who may come into contact with the virus. It is necessary to determine the conditions that would allow the safe reuse respirators and personal protection in this crisis. We found that heating (<100 {degrees}C) under various humidities (up to 100% RH at 75 {degrees}C) and ultraviolet (UV) irradiation were the most promising candidates for mask reuse in the modern hospital infrastructure (up to 20 cycles), when tested on a fabric with particle filtration efficiency [&ge;]95%. Treatments involving certain liquids and vapors may require caution, as steam, alcohol, and bleach all led to degradation in filtration efficiency, leaving the user vulnerable to viral aerosols.

9: Effects of temperature variation and humidity on the mortality of COVID-19 in Wuhan
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Posted 18 Mar 2020

Effects of temperature variation and humidity on the mortality of COVID-19 in Wuhan
7,450 downloads medRxiv occupational and environmental health

Yueling Ma, Yadong Zhao, Jiangtao Liu, Xiaotao He, Bo Wang, Shihua Fu, Jun Yan, Jingping Niu, Bin Luo

ObjectMeteorological parameters are the important factors influencing the infectious diseases like severe acute respiratory syndrome (SARS). This study aims to explore the association between coronavirus disease (COVID-19) death and weather parameters. MethodsIn this study, we collected the daily death number of COVID-19, meteorological and air pollutant data from 20 January, 2020 to 29 February, 2020 in Wuhan, China. Then, the generalized additive model was applied to explore the impact of temperature, humidity and diurnal temperature range on daily mortality of COVID-19. ResultsThere were in total 2299 COVID-19 mortality counts in Wuhan. A positive association with COVID-19 mortality was observed for diurnal temperature range (r = 0.44), but negative association for relative humidity (r = -0.32). In addition, each 1 unit increase in diurnal temperature range was only associated with a 2.92% (95% CI: 0.61%, 5.28%) increase in COVID-19 mortality at lag 3. However, both per 1 unit increase of temperature and absolute humidity were related to the decreased COVID-19 mortality at lag 3 and lag 5, respectively. ConclusionIn summary, this study suggests the temperature variation and humidity may be important factors affecting the COVID-19 mortality.

10: The impact of temperature and absolute humidity on the coronavirus disease 2019 (COVID-19) outbreak - evidence from China
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Posted 24 Mar 2020

The impact of temperature and absolute humidity on the coronavirus disease 2019 (COVID-19) outbreak - evidence from China
5,896 downloads medRxiv occupational and environmental health

Peng Shi, Yinqiao Dong, Huanchang Yan, Xiaoyang Li, Chenkai Zhao, Wei Liu, Miao He, Shixing Tang, Shuhua Xi

OBJECTIVETo investigate the impact of temperature and absolute humidity on the coronavirus disease 2019 (COVID-19) outbreak. DESIGNEcological study. SETTING31 provincial-level regions in mainland China. MAIN OUTCOME MEASURESData on COVID-19 incidence and climate between Jan 20 and Feb 29, 2020. RESULTSThe number of new confirm COVID-19 cases in mainland China peaked on Feb 1, 2020. COVID-19 daily incidence were lowest at -10 {degrees}C and highest at 10 {degrees}C, while the maximum incidence was observed at the absolute humidity of approximately 7 g/m3. COVID-19 incidence changed with temperature as daily incidence decreased when the temperature rose. No significant association between COVID-19 incidence and absolute humidity was observed in distributed lag nonlinear models. Additionally, A modified susceptible-exposed-infectious-recovered (M-SEIR) model confirmed that transmission rate decreased with the increase of temperature, leading to further decrease of infection rate and outbreak scale. CONCLUSIONTemperature is an environmental driver of the COVID-19 outbreak in China. Lower and higher temperatures might be positive to decrease the COVID-19 incidence. M-SEIR models help to better evaluate environmental and social impacts on COVID-19. What is already known on this topicO_LIMany infectious diseases present an environmental pattern in their incidence. C_LIO_LIEnvironmental factors, such as climate and weather condition, could drive the space and time correlations of infectious diseases, including influenza. C_LIO_LISevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can be transmitted through aerosols, large droplets, or direct contact with secretions (or fomites) as influenza virus can. C_LIO_LILittle is known about environmental pattern in COVID-19 incidence. C_LI What this study addsO_LIThe significant association between COVID-19 daily incidence and temperature was confirmed, using 3 methods, based on the data on COVID-19 and weather from 31 provincial-level regions in mainland China. C_LIO_LIEnvironmental factors were considered on the basis of SEIR model, and a modified susceptible-exposed-infectious-recovered (M-SEIR) model was developed. C_LIO_LISimulations of the COVID-19 outbreak in Wuhan presented similar effects of temperature on incidence as the incidence decrease with the increase of temperature. C_LI

11: Burnout among healthcare professionals during COVID-19 pandemic: a cross-sectional study
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Posted 13 Jun 2020

Burnout among healthcare professionals during COVID-19 pandemic: a cross-sectional study
5,366 downloads medRxiv occupational and environmental health

Mohammad Jalili, Mahtab Niroomand, Fahimeh Hadavand, Kataun Zeinali, Akbar Fotouhi

Background: The unpredictable nature of the new COVID-19 pandemic and the already alarming incidence of healthcare workers being affected can have a significant impact on the psychological well-being of the staff. Objective: To describe the prevalence of burnout among healthcare professionals and the associated factors. Design: Cross-sectional survey. Setting: Eight university affiliated hospitals in the capital city of Tehran, Iran. Participants: All healthcare workers at the study sites who had been taking care of COVID-19 patients. Measurements: Age, gender, marital status, having children, hospital, job category, experience, and work load, as well as the level of burnout in each subscale. Results: 326 persons (53.0%) experienced high levels of burnout. The average score in emotional exhaustion, depersonalization and lack of personal accomplishment was 26.6, 10.2, and 27.3, respectively. The level of burnout in the three subscales varied based on the personal as well as work related factors and gender was the only variable that was associated with high levels of all three domains. Limitations: There was no control group and thus we cannot claim a causal relationship between COVID-19 and the observed level of burnout. Not all confounding factors might have been accounted for. Conclusions: Burnout is prevalent among healthcare workers caring for COVID-19 patients. Age, gender, job category, and site of practice contribute to the level of burnout that the staff experience.

12: Disinfection of N95 Respirators with Ozone
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Posted 01 Jun 2020

Disinfection of N95 Respirators with Ozone
5,052 downloads medRxiv occupational and environmental health

Edward P Manning, Matthew D Stephens, Sannel Patel, Sylvie Dufresne, Bruce Silver, Patricia Gerbarg, Zach Gerbarg, Charles Dela Cruz, Lokesh Sharma

The coronavirus disease 2019 crisis is creating a shortage of personal protective equipment (PPE), most critically, N95 respirators for healthcare personnel. Our group was interested in the feasibility of ozone disinfection of N95 respirators as an alternative for healthcare professionals and organizations that might not have access to other disinfection devices. We tested the effectiveness of ozone on killing Pseudomonas aeruginosa (PsA) on three different N95 respirators: 3M 1860, 3M 1870, and 3M 8000. We used an ozone chamber that consisted of: an airtight chamber, an ozone generator, an ozone destruct unit, and an ozone UV analyzer. The chamber was capable of concentrating ozone up to 500 parts per million (ppm) from ambient air, creating an airtight seal, and precisely measuring ozone levels within the chamber. Exposure to ozone at 400 ppm with 80% humidity for two hours effectively killed bacteria on N95 respirators, types 1860, 1870, and 8000. There were no significant changes in filtration efficiency of the 1860 and 1870 type respirators for up to ten cycles of ozone exposure at similar conditions. There was no change in fit observed in the 1870 type respirator after ozone exposure. There was no significant change in the strap integrity of the 1870 type respirator after ozone exposure. Tests for filtration efficiency were not performed on the 8000 type respirator. Tests for fit or strap integrity were not performed on the 8000 or 1860 type respirators. This study demonstrates that an ozone application achieves a high level of disinfection against PsA, a vegetative bacteria that the CDC identifies as more difficult to kill than medium sized viruses such as SARS-CoV-2 (Covid-19). Furthermore, conditions shown to kill these bacteria did not damage or degrade respirator filtration. This is the first report of successful disinfection of N95 PPE with ozone of which the authors are aware. It is also the first report, to the authors' knowledge, to identify necessary conditions for ozone to kill organisms on N95 masks without degrading the function of N95 filters.

13: Microwave-Generated Steam Decontamination of N95 Respirators Utilizing Universally Accessible Materials
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Posted 25 Apr 2020

Microwave-Generated Steam Decontamination of N95 Respirators Utilizing Universally Accessible Materials
4,935 downloads medRxiv occupational and environmental health

Kate E Zulauf, Alex B Green, Alex N. Nguyen Ba, Tanush Jagdish, Dvir Reif, Robert Seeley, Alana Dale, James E Kirby

The SARS-CoV-2 pandemic has caused a severe, international shortage of N95 respirators, which are essential to protect healthcare providers from infection. Given the contemporary limitations of the supply chain, it is imperative to identify effective means of decontaminating, reusing, and thereby conserving N95 respirator stockpiles. To be effective, decontamination must result in sterilization of the N95 respirator without impairment of respirator filtration or user fit. Although numerous methods of N95 decontamination exist, none are universally accessible. In this work we describe a microwave-generated steam decontamination protocol for N95 respirators for use in healthcare systems of all sizes, geographies, and means. Using widely available glass containers, mesh from commercial produce bags, a rubber band, and a 1100W commercially available microwave, we constructed an effective, standardized, and reproducible means of decontaminating N95 respirators. Employing this methodology against MS2 phage, a highly conservative surrogate for SARS-CoV-2 contamination, we report an average 6-log10 plaque forming unit (PFU) (99.9999%) and a minimum 5-log10 PFU (99.999%) reduction after a single three-minute microwave treatment. Notably, quantified respirator fit and function were preserved, even after 20 sequential cycles of microwave steam decontamination. This method provides a valuable means of effective decontamination and reuse of N95 respirators by frontline providers facing urgent need.

14: Estimation of SARS-CoV-2 emissions from non-symptomatic cases
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Posted 03 May 2020

Estimation of SARS-CoV-2 emissions from non-symptomatic cases
4,762 downloads medRxiv occupational and environmental health

Michael Riediker, Dai-Hua Tsai

Importance: Cases of the coronavirus disease 2019 (COVID-19) with no or mild symptoms were reported to frequently transmit the disease even without direct contact. The severe acute respiratory syndrome virus (SARS-COV-2) was found at very high concentrations in swab and sputum of such cases. Objective: We aimed to estimate in a mathematical modeling study the virus release from such cases into different aerosol sizes by normal breathing and coughing, and what exposure can result from this in a room shared with such as case. Data Sources and Model: We combined the size-distribution of exhaled breath microdroplets for coughing and normal breathing with viral sputum concentrations as approximation for lung lining liquid to obtain an estimate of emitted virus levels. The resulting emission data fed a single-compartment model of airborne concentrations in a room of 50 m3, the size of a small office or medical exam room. Results: The estimated viral load in microdroplets emitted by simulated patients while breathing normally was on typical 0.0000049 copies/cm3 and could go up to 0.637 copies/cm3. The corresponding numbers for coughing simulated patients were 0.277 copies/cm3 and 36,030/cm3, respectively, per cough. The resulting concentrations in a room with a coughing emitter were always very high, up to 7.44 million copies/m3. However, also regular breathing microdroplets from high emitters was modelled to lead to 1248 copies/m3. Conclusions and Relevance: In this modelling study, breathing and coughing were estimated to release large numbers of viruses, ranging from thousands to millions of virus copies/m3 in a room with an emitter having a high viral load, depending on ventilation and microdroplet formation process. These findings suggest that strict respiratory protection may be needed when there is a chance to be in the same room with a patient - whether symptomatic or not - especially for a prolonged time.

15: Disposable N95 Masks Pass Qualitative Fit-Test But Have Decreased Filtration Efficiency after Cobalt-60 Gamma Irradiation
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Posted 30 Mar 2020

Disposable N95 Masks Pass Qualitative Fit-Test But Have Decreased Filtration Efficiency after Cobalt-60 Gamma Irradiation
4,418 downloads medRxiv occupational and environmental health

Avilash Cramer, Enze Tian, Sherry H. Yu, Mitchell Galanek, Edward Lamere, Ju Li, Rajiv Gupta, Michael P. Short

The current COVID-19 pandemic has led to a dramatic shortage of masks and other personal protective equipment (PPE) in hospitals around the globe [1]. One component of PPE that is in particular demand are disposable N95 face masks. To alleviate this, many methods of N95 mask sterilization have been studied and proposed with the hope of being able to safely reuse masks [2]. Two major considerations must be made when re-sterilizing masks: (1) the sterilization method effectively kills pathogens, penetrating into the fibers of the mask, and (2) the method does not degrade the operational integrity of the N95 filters. We studied Cobalt-60 (60Co) gamma irradiation as a method of effective sterilization without inducing mask degradation. Significant literature exists supporting the use of gamma radiation as a sterilization method, with viral inactivation of SARS-CoV reported at doses of at most 10 kGy [3], with other studies supporting 5 kGy for many types of viruses [4]. However, concerns have been raised about the radiation damaging the fiber material within the mask, specifically by causing cross-linking of polymers, leading to cracking and degradation during fitting and/or deployment [5, 6]. A set of 3M 8210 and 9105 masks were irradiated using MITs 60Co irradiator. Three masks of each type received 0 kiloGray (kGy), 10 kGy and 50 kGy of approximately 1.3 MeV gamma radiation from the circular cobalt sources, at a dose rate of 2.2kGy per hour. Following this sterilization procedure, the irradiated masks passed a OSHA Gerson Qualitative Fit Test QLFT 50 (saccharin apparatus) [7] when donned correctly, performed at the Brigham and Womens Hospital, in a blinded study repeated in triplicate. However, the masks filtration of 0.3 {micro}m particles was significantly degraded, even at 10 kGy. These results suggest against gamma, and possibly all ionizing radiation, as a method of disposable N95 sterilization. Even more importantly, they argue against using the qualitative fit test alone to assess mask integrity.

16: Characterizing occupations that cannot work from home: a means to identify susceptible worker groups during the COVID-19 pandemic
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Posted 24 Mar 2020

Characterizing occupations that cannot work from home: a means to identify susceptible worker groups during the COVID-19 pandemic
4,328 downloads medRxiv occupational and environmental health

Marissa G. Baker

IntroductionAs the COVID-19 pandemic spreads globally, public health guidance is advising all workers to work from home. However, not all workers are employed in occupations which can be done from home. These workers are at an increased risk for exposure to SARS-CoV-2due to increased interaction with the public and other workers, and also potentially at an increased risk for job displacement as more extreme public health measures (such as closing of retail operations or enforcing shelter in place) occur. MethodsTo characterize the occupations least likely to be able to work from home, national employment and wage data maintained by the United States Bureau of Labor Statistics (BLS) was merged with measures from the BLS O*NET survey data, which ranks occupations by a variety of physical, ergonomic, psychosocial, and structural exposures. Noting that the work that could most easily be done at home would be work done on a computer that does not rely on interaction with the public, O*NET measures quantifying the importance of computer use at work, and the importance of working with or performing for the public at work were utilized. ResultsFrom this analysis, 19.5% (28.2 M) of the United States workforce covered by O*NET are employed in occupations where working from home would be difficult, due to minimal use of computer at work, and a high level of interaction with the public. These workers tend to be in service occupations, including retail and food service, protective service occupations, and transportation occupations such as bus drivers. About 25% (35.6 M) of the United States workforce covered by O*NET are employed in occupations where working from home could likely be more easily accommodated, as these workers do much of their work on computers and interaction with the public is not important. These workers tend to be in technology, computer, management, administrative, financial, engineering, and some science occupations, which typically have higher pay than occupations which cannot be done at home. ConclusionsThe workers in occupations that have minimal computer use, and high interaction with the public are least likely to be able to work from home during a public health emergency. These workers could also be at an increased risk for job displacement if public-facing establishments close or alter their business model in the face of increased public health restrictions. Occupations where working from home is not possible tend to have lower annual median incomes than occupations where working from home is possible, increasing the vulnerability of these workers. Characterizing which occupational groups are least likely to be able to work from home can inform public health risk management and prioritize occupational sectors where additional workplace protections are necessary.

17: SARS-CoV-2 RNA titers in wastewater anticipated COVID-19 occurrence in a low prevalence area
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Posted 25 Apr 2020

SARS-CoV-2 RNA titers in wastewater anticipated COVID-19 occurrence in a low prevalence area
4,292 downloads medRxiv occupational and environmental health

Walter Randazzo, Pilar Truchado, Enric Cuevas Ferrando, Pedro Simon, Ana Allende, Gloria Sanchez

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused more than 200,000 reported COVID-19 cases in Spain resulting in more than 20,800 deaths as of April 21, 2020. Faecal shedding of SARS-CoV-2 RNA from COVID-19 patients has extensively been reported. Therefore, we investigated the occurrence of SARS-CoV-2 RNA in six wastewater treatments plants (WWTPs) serving the major municipalities within the Region of Murcia (Spain), the area with the lowest COVID-19 prevalence within Iberian Peninsula. Firstly, an aluminum hydroxide adsorption-precipitation concentration method was tested using a porcine coronavirus (Porcine Epidemic Diarrhea Virus, PEDV) and mengovirus (MgV). The procedure resulted in average recoveries of 10.90 and 10.85% in influent water and 3.29 and 6.19 in effluent water samples for PEDV and MgV, respectively. Then, the method was used to monitor the occurrence of SARS-CoV-2 from March 12 to April 14, 2020 in influent, secondary and tertiary effluent water samples. By using the real-time RT-PCR (RT-qPCR) Diagnostic Panel validated by US CDC that targets three regions of the virus nucleocapsid (N) gene, we estimated quantification of SARS-CoV-2 RNA titers in untreated wastewater waters of 5.38 log genomic copies/L on average. Two secondary water samples resulted positive (2 out of 18) and all tertiary water samples tested as negative (0 out 12). This environmental surveillance data were compared to declared COVID-19 cases at municipality level, revealing that SARS-CoV-2 was circulating among the population even before the first cases were reported by local or national authorities in many of the cities where wastewaters have been sampled. The detection of SARS-CoV-2 in wastewater in early stages of the spread of COVID-19 highlights the relevance of this strategy as an early indicator of the infection within a specific population. At this point, this environmental surveillance could be implemented by municipalities right away as a tool, designed to help authorities to coordinate the exit strategy to gradually lift its coronavirus lockdown.

18: Strategies to minimize SARS-CoV-2 transmission in classroom settings: Combined impacts of ventilation and mask effective filtration efficiency
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Posted 04 Jan 2021

Strategies to minimize SARS-CoV-2 transmission in classroom settings: Combined impacts of ventilation and mask effective filtration efficiency
3,867 downloads medRxiv occupational and environmental health

David A. Rothamer, Scott Sanders, Douglas Reindl, Timothy H. Bertram

The impact of the COVID-19 pandemic continues to be significant and global. As the global community learns more about the novel coronavirus SARS-CoV-2, there is strong evidence that a significant modality of transmission is via the long-range airborne route, referred to here as aerosol transmission. In this paper, we evaluate the efficacy of ventilation, mask effective filtration efficiency, and the combined effect of the two on the reduction of aerosol infection probability for COVID-19 in a classroom setting. The Wells-Riley equation is used to predict the conditional probability of infection for three distinct airborne exposure scenarios: (1) an infectious instructor exposing susceptible students; (2) an infectious student exposing other susceptible students; and (3) an infectious student exposing a susceptible instructor. Field measurements were performed in a classroom using a polydisperse neutralized salt (NaCl) aerosol, generated in a size range consistent with human-generated SARS-CoV-2 containing bioaerosols, as a safe surrogate. Measurements included time-resolved and size-resolved NaCl aerosol concentration distributions and size-resolved effective filtration efficiency of different masks with and without mask fitters. The measurements were used to validate assumptions and inputs for the Wells-Riley model. Aerosol dynamics and distribution measurements confirmed that the majority of the classroom space is uniform in aerosol concentration within a factor of 2 or better for distances > 2 m from the aerosol source. Mask effective filtration efficiency measurements show that most masks fit poorly with estimated leakage rates typically > 50%, resulting in significantly reduced effective filtration efficiency. However, effective filtration efficiencies approaching the mask material filtration efficiency were achievable using simple mask fitters. Wells-Riley model results for the different scenarios suggest that ventilation of the classroom alone is not able to achieve infection probabilities less than 0.01 (1%) for air exchanges rates up to 10 h-1 and an event duration of one hour. The use of moderate to high effective filtration efficiency masks by all individuals present, on the other hand, was able to significantly reduce infection probability and could achieve reductions in infection probability by 5x, 10x, or even >100x dependent on the mask used and use of a mask fitter. This enables conditional infection probabilities < 0.001 (0.1%) or even < 0.0001 (0.01%) to be reached with the use of masks and mask fitters alone. Finally, the results demonstrate that the reductions provided by ventilation and masks are synergistic and multiplicative. The results reinforce the use of properly donned masks to achieve reduced aerosol transmission of SARS-CoV-2 and other infectious diseases transmitted via respiratory aerosol indoors and provide new motivation to further improve the effective filtration efficiency of common face coverings through improved design, and/or the use of mask fitters.

19: Estimating the burden of United States workers exposed to infection or disease: a key factor in containing risk of COVID-19 infection
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Posted 06 Mar 2020

Estimating the burden of United States workers exposed to infection or disease: a key factor in containing risk of COVID-19 infection
3,731 downloads medRxiv occupational and environmental health

Marissa G. Baker, Trevor K. Peckham, Noah S. Seixas

IntroductionWith the global spread of COVID-19, there is a compelling public health interest in quantifying who is at increased risk of disease. Occupational characteristics, such as interfacing with the public and being in close quarters with other workers, not only put workers at high risk for disease, but also make them a nexus of disease transmission to the community. This can further be exacerbated through presenteeism, the term used to describe the act of coming to work despite being symptomatic for disease. Understanding which occupational groups are exposed to infection and disease in the workplace can help to inform public health risk response and management for COVID-19, and subsequent infectious disease outbreaks. MethodsTo estimate the burden of United States workers exposed to infection and disease in the workplace, national employment data (by Standard Occupational Classification) maintained by the Bureau of Labor Statistics (BLS) was merged with BLS O*NET survey data, which ranks occupations with particular physical, ergonomic, and structural exposures. For this analysis, occupations reporting exposure to infection or disease more than once a month was the focus. ResultsBased on our analyses, approximately 10% (14.4 M) of United States workers are employed in occupations where exposure to disease or infection occurs at least once per week. Approximately 18.4% (26.7 M) of all United States workers are employed in occupations where exposure to disease or infection occurs at least once per month. While the majority of exposed workers are employed in healthcare sectors, other occupational sectors also have high proportions of exposed workers. These include protective service occupations (e.g. police officers, correctional officers, firefighters), office and administrative support occupations (e.g. couriers and messengers, patient service representatives), education occupations (e.g. preschool and daycare teachers), community and social services occupations (community health workers, social workers, counselors), and even construction and extraction occupations (e.g. plumbers, septic tank installers, elevator repair). ConclusionsThe large number of persons employed in a wide variety of occupations with frequent exposure to infection and disease underscore the importance of all workplaces developing risk response plans for COVID-19. This work also serves as an important reminder that the workplace is a key locus for public health interventions, which could protect both workers and the communities they serve.

20: A Scalable Method of Applying Heat and Humidity for Decontamination of N95 Respirators During the COVID-19 Crisis
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Posted 14 Apr 2020

A Scalable Method of Applying Heat and Humidity for Decontamination of N95 Respirators During the COVID-19 Crisis
3,425 downloads medRxiv occupational and environmental health

Loïc Anderegg, Cole Meisenhelder, Chiu Oan Ngooi, Lei Liao, Wang Xiao, Steven Chu, Yi Cui, John M Doyle

A lack of N95 respirators during the COVID-19 crisis has placed healthcare workers at risk. It is important for any N95 reuse strategy to determine the effects that proposed protocols would have on the physical functioning of the mask, as well as the practical aspects of implementation. Here we propose and implement a method of heating N95 respirators with moisture (85{degrees}C, 60-85% humidity). We test both mask filtration efficiency and fit to validate this process. Our tests focus on the 3M 1860, 3M 1870, and 3M 8210 Plus N95 models. After five cycles of the heating procedure, all three respirators pass both quantitative fit testing (score of >100) and show no degradation of mask filtration efficiency. We also test the Chen Heng V9501 KN95 and HKYQ N95 finding no degradation of mask filtration efficiency, however even for unheated masks these scored <50 for every fit test. The heating method presented here is scalable from individual masks to over a thousand a day with a single industrial convection oven, making this method practical for local application inside health-care facilities.

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