Last data update: Mar 17, 2025. (Total: 48910 publications since 2009)
Records 1-30 (of 66 Records) |
Query Trace: Bergman M[original query] |
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Evaluating source control efficacy against exhaled submicron particles: Total outward leakage of surgical masks and half facepiece respirators across a spectrum of particle sizes
Yang W , Myers WR , Bergman M , Fisher E , Ryan KJ , Vollmer B , Portnoff L , Zhuang Z . Aerosol Sci Technol 2024 The size of airborne particles emitted from infected individuals is crucial in the transmission of respiratory viruses. The use of source control devices is essential for interrupting the transmission of exhaled submicron particles, particularly in healthcare settings with high infection risk. This study evaluated the efficacy of five types of source control devices, commonly used in healthcare settings, in mitigating the transmission of exhaled submicron particles (20–210 nm). Total outward leakage (TOL) of these devices was analyzed across different particle sizes, and the TOL mean diameter (TOLMD) was calculated to characterize particle size distribution. The devices tested included N95 filtering facepiece respirators (N95 FFRs), N95 FFRs with an exhalation valve (N95 FFRV), surgical masks (SMs), elastomeric half-mask respirators (EHMRs), and EHMRs with a SM covering the exhalation valve (EHMRSM). The study also examined the effects of faceseal and flowrate on TOL and particle size characteristics. Results indicated that TOL varied with particle size, increasing from 40 to 90 nm before stabilizing. Aerosols larger than 90 nm had significantly higher TOL compared to smaller aerosols. Higher flow rates increased TOL for EHMR and EHMRSM across all particle sizes. Improved faceseal on N95 FFRs and SMs significantly reduced TOL and decreased TOLMD. The study underscored that using well-fitting devices without exhalation valves is crucial for preventing the transmission of exhaled aerosols potentially carrying viruses, in particular for larger particle sizes. This is especially crucial in the absence of proper indoor ventilation and other control measures. © This work was authored as part of the Contributor’s official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law. |
Total outward leakage of face-worn products used by the general public for source control
Yang W , Myers W , Bergman M , Fisher E , Ryan KJ , Vollmer B , Portnoff L , Zhuang Z . Am J Infect Control 2024 BACKGROUND: During COVID-19 pandemic, the general public used any face-worn products they could get to overcome the shortage of N95 respirators and surgical masks. These products, often not meeting any standards, raised concerns about their effectiveness in reducing the spread of respiratory viruses. METHODS: This study quantified total outward leakage (TOL) of units from nine face-worn product categories used by members of the general public. A benchtop system was devised to test two units from each category on two different-sized headforms with silicone elastomer skin. Each unit was donned five times per headform. RESULTS: Both face-worn product category and headform size significantly affected TOL (P-Value <0.05). The TOL of tested face-worn products varied from 10% to 58% depending on both model and headform size. Face-worn products donned on the medium headform had a higher mean TOL compared to those donned on the larger headform. CONCLUSIONS: Overall, single-layer cloth masks are the least effective measure for source control due to their highest TOL among the tested face-worn products. Three-layer disposable face masks may be a favorable option for source control among the public. A standard should be developed for face-worn product design and manufacturing to accommodate different facial sizes. |
Next-generation custom-fit reusable respiratory protective device with continuous fit monitoring - Part II: Continuous fit monitoring
Park S , Tian Y , Bergman M , Pollard J , Zhuang Z , Jayaraman S . J Int Soc Respir Prot 2024 41 (1) 38-56 Filtering facepiece respirators (FFRs) are manufactured in discrete sizes, with some models being limited in accommodating the fit of some sex and race combinations. This study presents the development of a custom-fit respiratory protective device (RPD) which conforms to a user's facial features and flexes and moves with facial movements during use. Our design also integrates a pressure-sensing network, which continuously monitors fit and will alert the user when the fit is compromised. In this Part II of the three-part series, we design and incorporate a continuous fit monitoring system in the RPD designed in Part I to enhance its role in protecting users from inhalation hazards in an effective manner during its use. The fit monitoring system comprises a fabric-based sensor network integrated into the RPD and an Android-based App designed to alert the user when the pressure at the faceseal falls below a given threshold established during the initial configuration of the RPD for the user. We also develop algorithms for the incorporation of the sensor slots and data buses into the custom-fit RPD using the Taxonomy of Landmarks defined in Part I. We enhance the structure developed in Part I to secure the sensor network during the use of the RPD. We develop algorithms for customizing a fastening hub to suit the head profiles of individuals to enable them to don the RPD quickly, easily, effectively, and in a repeatable manner. We demonstrate the successful application of the total design methodology by creating digital prototypes for three individuals with different facial profiles and make further advances to our goal of ensuring equitable respiratory protection for all including children, for whom RPDs are currently limited. |
Convenience sampling yields no evidence of SARS-CoV-2 infection in free-ranging mammalian wildlife in Arizona, USA, 2021-23
Yaglom HD , Van Pelt L , Howard AL , Jansen B , Smith P , Sorensen R , Hecht G , Venkat H , Justice-Allen A , Bergman DL , Engelthaler DM . J Wildl Dis 2023 ![]() Susceptibility of free-ranging US wildlife to SARS-CoV-2 infection has been documented. Nasal or oral swabs and blood from 337 wild mammals (31 species) in Arizona USA, tested for antibodies and by reverse-transcription PCR, did not reveal evidence of SARS-CoV-2. Broader surveillance efforts are necessary to understand the role of wildlife. |
Reemergence of a big brown bat lyssavirus rabies variant in striped skunks in Flagstaff, Arizona, USA, 2021-2023
Gilbert AT , Van Pelt LI , Hastings LA , Gigante CM , Orciari LA , Kelley S , Fitzpatrick K , Condori REC , Li Y , Brunt S , Davis A , Hopken MW , Mankowski CCP , Wallace RM , Rupprecht CE , Chipman RB , Bergman DL . Vector Borne Zoonotic Dis 2024 ![]() ![]() Background: Throughout the Americas, Lyssavirus rabies (RV) perpetuates as multiple variants among bat and mesocarnivore species. Interspecific RV spillover occurs on occasion, but clusters and viral host shifts are rare. The spillover and host shift of a big brown bat (Eptesicus fuscus) RV variant Ef-W1 into mesocarnivores was reported previously on several occasions during 2001-2009 in Flagstaff, Arizona, USA, and controlled through rabies vaccination of target wildlife. During autumn 2021, a new cluster of Ef-W1 RV cases infecting striped skunks (Mephitis mephitis) was detected from United States Department of Agriculture enhanced rabies surveillance in Flagstaff. The number of Ef-W1 RV spillover cases within a short timeframe suggested the potential for transmission between skunks and an emerging host shift. Materials and Methods: Whole and partial RV genomic sequencing was performed to evaluate the phylogenetic relationships of the 2021-2023 Ef-W1 cases infecting striped skunks with earlier outbreaks. Additionally, real-time reverse-transcriptase PCR (rtRT-PCR) was used to opportunistically compare viral RNA loads in brain and salivary gland tissues of naturally infected skunks. Results: Genomic RV sequencing revealed that the origin of the 2021-2023 epizootic of Ef-W1 RV was distinct from the multiple outbreaks detected from 2001-2009. Naturally infected skunks with the Ef-W1 RV showed greater viral RNA loads in the brain, but equivalent viral RNA loads in the mandibular salivary glands, compared to an opportunistic sample of skunks naturally infected with a South-Central skunk RV from northern Colorado, USA. Conclusion: Considering a high risk for onward transmission and spread of the Ef-W1 RV in Flagstaff, public outreach, enhanced rabies surveillance, and control efforts, focused on education, sample characterization, and vaccination, have been ongoing since 2021 to mitigate and prevent the spread and establishment of Ef-W1 RV in mesocarnivores. |
Understanding three approaches to reporting sudden unexpected infant death in the USA
Erck Lambert AB , Parks S , Bergman K , Cottengim C , Woster A , Shaw E , Ma H , Heitmann R , Riehle-Colarusso T , Shapiro-Mendoza C . Inj Prev 2024 INTRODUCTION: In the USA each year, there are approximately 3400 sudden unexpected infant (<1 year of age) deaths (SUID) which occur without an obvious cause before an investigation. SUID includes the causes of death (COD) undetermined/unknown, sleep-related suffocation/asphyxia and sudden infant death syndrome (SIDS); these are often called SUID subtypes. Three common ways SUID subtypes are grouped (SUID subtype groups) include International Classification of Diseases (ICD) Codes, SUID Case Registry Categories or Child Death Review (CDR)-Assigned Causes. These groups are often used to monitor SUID trends and characteristics at the local, state and national levels. We describe and compare the characteristics of these three SUID subtype groups. DISCUSSION: SUID subtype groups are distinct and not directly interchangeable. They vary in purpose, strengths, limitations, uses, history, data years available, population coverage, assigning entity, guidance documentation and information available to assign subtypes. CONCLUSION: Making informed decisions about which SUID subtype group to use is important for reporting statistics, increasing knowledge of SUID epidemiology and informing prevention strategies. |
Establishment-level safety analytics: a scoping review
Foreman AM , Friedel JE , Ezerins ME , Matthews R , Nicholson RE , Wellersdick L , Bergman S , Açıkgöz Y , Ludwig TD , Wirth O . Int J Occup Saf Ergon 2024 1-12 The use of data analytics has seen widespread application in fields such as medicine and supply chain management, but their application in occupational safety has only recently become more common. The purpose of this scoping review was to summarize studies that employed analytics within establishments to reveal insights about work-related injuries or fatalities. Over 300 articles were reviewed to survey the objectives, scope and methods used in this emerging field. We conclude that the promise of analytics for providing actionable insights to address occupational safety concerns is still in its infancy. Our review shows that most articles were focused on method development and validation, including studies that tested novel methods or compared the utility of multiple methods. Many of the studies cited various challenges in overcoming barriers caused by inadequate or inefficient technical infrastructures and unsupportive data cultures that threaten the accuracy and quality of insights revealed by the analytics. |
Total outward leakage of half-mask respirators and surgical masks used for source control
Myers WR , Yang W , Ryan KJ , Bergman M , Fisher E , Soo JC , Zhuang Z . J Occup Environ Hyg 2023 1-15 Both respirators and surgical masks (SM) are used as source control devices. During the COVID-19 pandemic, there was much interest in understanding the extent of particle total outward leakage (TOL) from these devices. The objective of this study was to quantify the TOL for five categories of devices: SMs, National Institute for Occupational Safety and Health (NIOSH®) Approved N95(®) filtering facepiece respirators (FFRs) without exhalation valves, NIOSH Approved N95 FFRs with exhalation valves (N95 FFRV), NIOSH Approved elastomeric half-mask respirators (EHMRs) with exhalation valves, and NIOSH Approved EHMRs with an SM covering the exhalation valve (EHMRSM). A benchtop test system was designed to test two models of each device category. Each device was mounted on a headform at three faceseal levels (0% faceseal, 50% faceseal, and 100% faceseal). At each faceseal level, the TOL was assessed at three flowrates of minute ventilations of 17, 28, and 39 L/min. The experimental design was a split-split-plot configuration. Device type, faceseal level, flowrate, and the interaction of device type and faceseal level were found to have a significant effect ( P - Value <0.05) on the TOL.This study found that the N95 FFRs without exhalation valves had the lowest mean TOL. The SMs had about three times higher TOL than the N95 FFRs without exhalation valves. The TOL of the N95 FFRV was comparable to that of the SM at 0% and 50% faceseal on average over all conditions, but the N95 FFRV had a significantly higher TOL than the SM at a 100% faceseal. The EHMRs had the highest TOL because of the exhalation valve. Using an SM to cover the exhalation valve did not improve the EHMRs' efficiency in mitigating the TOL. Caution should be exercised when using N95 FFRVs as a source control measure against respiratory activities with heavy work rates, such as performing CPR. Results of this study showed that reduced faceseal leakage for N95 FFRs and SMs improves source control. |
Fit evaluation of NIOSH Approved N95 filtering facepiece respirators with various skin protectants: a pilot study
Bergman MS , Grinshpun SA , Yermakov MV , Zhuang Z , Vollmer BE , Yoon KN . J Occup Environ Hyg 2023 20 (9) 1-10 Widespread disease outbreaks can result in prolonged wear times of National Institute for Occupational Safety and Health Approved N95 filtering facepiece respirators by healthcare personnel. Prolonged wear times of these devices can cause the development of various adverse facial skin conditions. Healthcare personnel have been reported to apply "skin protectants" to the face to reduce pressure and friction of respirators. Because tight-fitting respirators rely on a good face seal to protect the wearer, it is important to understand if fit is affected when skin protectants are used. This laboratory pilot study included 10 volunteers who performed quantitative fit tests to evaluate respirator fit while wearing skin protectants. Three N95 filtering facepiece respirator models and three skin protectants were evaluated. Three replicate fit tests were performed for each combination of subject, skin protectant (including a control condition of no protectant), and respirator model. Fit Factor (FF) was affected differently by the combination of protectant type and respirator model. The main effects of protectant type and respirator model were both significant (p <0.001); additionally, their interaction was significant (p = 0.02), indicating FF is affected by the combined effects of protectant type and respirator model. Compared to the control condition, using a bandage-type or surgical tape skin protectant decreased the odds of passing the fit test. Using a barrier cream skin protectant also decreased the odds of passing the fit test across all models compared to the control condition; however, the probability of passing a fit test was not statistically significantly different from the control condition (p = 0.174). These results imply that all three skin protectants reduced mean fit factors for all N95 filtering facepiece respirator models tested. The bandage-type and surgical tape skin protectants both reduced fit factors and passing rates to a greater degree than the barrier cream. Respirator users should follow respirator manufacturers' guidance on the use of skin protectants. If a skin protectant is to be worn with a tight-fitting respirator, the fit of the respirator should be evaluated with the skin protectant applied before use in the workplace. |
Adeno-associated virus type 2 in US children with acute severe hepatitis.
Servellita V , Gonzalez AS , Lamson DM , Foresythe A , Huh HJ , Bazinet AL , Bergman NH , Bull RL , Garcia KY , Goodrich JS , Lovett SP , Parker K , Radune D , Hatada A , Pan CY , Rizzo K , Bertumen JB , Morales C , Oluniyi PE , Nguyen J , Tan J , Stryke D , Jaber R , Leslie MT , Lyons Z , Hedman HD , Parashar U , Sullivan M , Wroblewski K , Oberste MS , Tate JE , Baker JM , Sugerman D , Potts C , Lu X , Chhabra P , Pediatric Hepatitis of Unknown Etiology Working Group , Ingram LA , Shiau H , Britt W , Sanchez LHG , Ciric C , Rostad CA , Vinjé J , Kirking HL , Wadford DA , Raborn RT , St George K , Chiu CY . Nature 2023 ![]() As of August 2022, clusters of acute severe hepatitis of unknown etiology in children have been reported from 35 countries, including the United States(1,2). Previous studies have found human adenoviruses (HAdVs) in the blood from cases in Europe and the United States(3-7), although it is unclear whether this virus is causative. Here we used PCR testing, viral enrichment based sequencing, and agnostic metagenomic sequencing to analyze samples from 16 HAdV-positive cases from October 1, 2021 to May 22, 2022, in parallel with 113 controls. In blood from 14 cases, adeno-associated virus 2 (AAV2) sequences were detected in 93% (13 of 14), compared to 4 (3.5%) of 113 controls (P<0.001) and to 0 of 30 patients with hepatitis of defined etiology (P<0.001). In controls, HAdV-41 was detected in blood from 9 (39.1%) of the 23 patients with acute gastroenteritis (without hepatitis), including 8 of 9 patients with positive stool HAdV testing, but co-infection with AAV2 was observed in only 3 (13.0%) of these 23 patients versus 93% of cases (P<0.001). Co-infections by Epstein-Barr virus (EBV), human herpesvirus 6 (HHV-6), and/or enterovirus A71 (EV-A71) were also detected in 12 (85.7%) of 14 cases, with higher herpesvirus detection in cases versus controls (P<0.001). Our findings suggest that the severity of the disease is related to co-infections involving AAV2 and one or more helper viruses. |
A manikin-based assessment of loose-fitting powered air-purifying respirator performance at variable flow rates and work rates
Strickland KT , Bergman MS , Xu S , Zhuang Z . J Occup Environ Hyg 2023 20 (7) 1-14 Loose-fitting powered air-purifying respirators (PAPRs) are used in healthcare settings, although barriers to routine, everyday usage remain, including usability concerns and potential interference with work activities. Loose-fitting PAPRs are approved by the National Institute for Occupational Safety and Health (NIOSH) and must meet minimum performance requirements, including a minimum airflow requirement of 170 L/min. One course of action to address usability concerns is to allow for the use of PAPRs designed with reduced airflow rates. The primary objective of this study was to assess the effect of PAPR flow rate and user work rate on PAPR performance, using a manikin-based assessment method. PAPR performance was quantified using "Manikin Fit Factor" (mFF), a ratio of the challenge aerosol concentration to the in-facepiece concentration. Flow rates from 50-215 L/min and low, moderate, and high work rates were tested. Two models of NIOSH Approved® loose-fitting facepiece PAPRs were tested, both having an Occupational Safety and Health Administration Assigned Protection Factor (APF), or expected level of protection, of 25. A two-way analysis of variance with an effect size model was run for each PAPR model to analyze the effects of work rate and flow rate on PAPR performance. Flow rate and work rate were found to be significant variables impacting PAPR performance. At low and moderate work rates and flow rates below the NIOSH minimum of 170 L/min, mFF was greater than or equal to 250, which is ten times the OSHA APF of 25 for loose-fitting facepiece PAPRs. At high work rates and flow rates below 170 L/min, mFF was not greater than or equal to 250. These results suggest that some loose-fitting facepiece PAPRs designed with a flow rate lower than the current NIOSH requirement of 170 L/min may provide respirator users with expected protection at low and moderate work rates. However, when used at high work rates, some loose-fitting facepiece PAPRs designed with lower flow rates may not provide the expected level of protection. |
Establishment-level occupational safety analytics: Challenges and opportunities
Foreman AM , Friedel JE , Ludwig TD , Ezerins ME , Açikgöz Y , Bergman SM , Wirth O . Int J Ind Ergon 2023 94 ![]() In occupational safety and health, big data and analytics show promise for the prediction and prevention of workplace injuries. Advances in computing power and analytical methods have allowed companies to reveal insights from the “big” data that previously would have gone undetected. Despite the promise, occupational safety has lagged behind other industries, such as supply chain management and healthcare, in terms of exploiting the potential of analytics and much of the data collected by organizations goes unanalyzed. The purpose of the present paper is to argue for the broader application of establishment-level safety analytics. This is accomplished by defining the terms, describing previous research, outlining the necessary components required, and describing knowledge gaps and future directions. The knowledge gaps and future directions for research in establishment-level analytics are categorized into readiness for analytics, analytics methods, technology integration, data culture, and impact of analytics. © 2023 |
Two decades of diabetes prevention efforts: A call to innovate and revitalize our approach to lifestyle change
Golovaty I , Ritchie ND , Tuomilehto J , Mohan V , Ali MK , Gregg EW , Bergman M , Moin T . Diabetes Res Clin Pract 2022 198 110195 The impact of global diabetes prevention efforts has been modest despite the promise of landmark diabetes prevention trials nearly twenty years ago. While national and regional initiatives show potential, challenges remain to adapt large-scale strategies in the real-world that fits individuals and their communities. Additionally, the sedentary lifestyle changes during the COVID-19 pandemic and guidelines that now call for earlier screening (e.g., US Preventative Task Force) will increase the pool of eligible adults worldwide. Thus, a more adaptable, person-centered approach that expands the current toolkit is urgently needed to innovate and revitalize our approach to diabetes prevention. This review identifies key priorities to optimize the population-level delivery of diabetes prevention based on a consensus-based evaluation of the current evidence among experts in global translational programs; key priorities identified include (1) participant eligibility, (2) intervention intensity, (3) delivery components, (4) behavioral economics, (5) technology, and (6) the role of pharmacotherapy. We offer a conceptual framework for a broader, person-centered approach to better address an individual's risk, readiness, barriers, and digital competency. |
Prevalence and mortality among children with anorectal malformation: A multi-country analysis.
Kancherla V , Sundar M , Tandaki L , Lux A , Bakker MK , Bergman JE , Bermejo-Sánchez E , Canfield MA , Dastgiri S , Feldkamp ML , Gatt M , Groisman B , Hurtado-Villa P , Kallen K , Landau D , Lelong N , Lopez-Camelo J , Martinez LE , Mastroiacovo P , Morgan M , Mutchinick OM , Nance AE , Nembhard WN , Pierini A , Sipek A , Stallings EB , Szabova E , Tagliabue G , Wertelecki W , Zarante I , Rissmann A . Birth Defects Res 2022 115 (3) 390-404 ![]() We examined the total prevalence, trends in prevalence, and age-specific mortality among individuals with anorectal malformation (ARM) METHODS: We conducted a retrospective cohort study using data from 24 population- and hospital-based birth defects surveillance programs affiliated with the International Clearinghouse for Birth Defects Surveillance and Research (ICBDSR) from 18 countries and for births from 1974 to 2014. We estimated pooled and program-specific total prevalence per 10,000 total births. Poisson regression was used to assess time trends in prevalence from 2001 to 2012 when most programs contributed data. We calculated selected age-specific proportions of deaths, stratified by case status RESULTS: The pooled total prevalence of ARM was 3.26 per 10,000 total births (95% Confidence Interval = 3.19, 3.32) for birth years 1974-2014. About 60% of cases were multiple or syndromic. Prevalence of multiple, syndromic, and stillborn cases decreased from 2001 to 2012. The first week mortality proportion was 12.5%, 3.2%, 28.3%, and 18.2% among all, isolated, multiple, and syndromic cases, respectively CONCLUSIONS: ARM is relatively rare, with multiple and syndromic cases showing decreasing prevalence during the study period. Mortality is a concern during the first week of life, and especially among multiple and syndromic cases. Our descriptive epidemiological findings increase our understanding of geographic variation in the prevalence of ARM and can be used to plan needed clinical services. Exploring factors influencing prevalence and mortality among individuals with ARM could inform future studies. |
Do employees work schedules put them at-risk The role of shift scheduling and holidays in predicting near miss and incident likelihood
Laske MM , Hinson PE , Acikgoz Y , Ludwig TD , Foreman AM , Bergman SM . J Safety Res 2022 83 1-7 Introduction: Using crew scheduling and injury incident data from a Fortune 500 manufacturing company, this study analyzed the effect of consecutive shifts and shifts near holidays on near misses and incidents. Methods: Logistic regressions were conducted with consecutive workdays, days near holidays, and time of shift as predictors of incident and near miss outcomes. Results: The logistic regression analysis indicated that working consecutive day shifts increases the probability of an incident occurring, with the fourth consecutive shift resulting in the most risk. The consecutive shift pattern did not replicate to employees working the night shift. However, the first and second shifts when transferring to a night schedule appear to have a greater chance of incident. Shifts near holidays did not have a significantly higher risk than other shifts. Practical application: The current research suggests that organizations can use similar analytic techniques to determine if shift scheduling might be related to increased risk and allocate resources to mitigate hazards during those peak probability shifts. 2022 National Safety Council and Elsevier Ltd |
A multicountry analysis of prevalence and mortality among neonates and children with bladder exstrophy
Kancherla V , Tandaki L , Sundar M , Lux A , Bakker MK , Bergman JE , Bermejo-Sánchez E , Canfield MA , Feldkamp ML , Groisman B , Hurtado-Villa P , Källén K , Landau D , Lelong N , Lopez-Camelo J , Mastroiacovo P , Morgan M , Mutchinick OM , Nance AE , Nembhard WN , Pierini A , Šípek A , Stallings EB , Szabova E , Wertelecki W , Zarante I , Rissmann A . Am J Perinatol 2022 OBJECTIVE: Bladder exstrophy (BE) is a rare but severe birth defect affecting the lower abdominal wall and genitourinary system. The objective of the study is to examine the total prevalence, trends in prevalence, and age-specific mortality among individuals with BE. STUDY DESIGN: We conducted a retrospective cohort study. Data were analyzed from 20 birth defects surveillance programs, members of the International Clearinghouse for Birth Defects Surveillance and Research in 16 countries. Live births, stillbirths, and elective terminations of pregnancy for fetal anomaly (ETOPFA) diagnosed with BE from 1974 to 2014. Pooled and program-specific prevalence of BE per 100,000 total births was calculated. The 95% confidence intervals (CI) for prevalence were estimated using Poisson approximation of binomial distribution. Time trends in prevalence of BE from 2000 to 2014 were examined using Poisson regression. Proportion of deaths among BE cases was calculated on the day of birth, day 2 to 6, day 7 to 27, day 28 to 364, 1 to 4 years, and ≥5 years. Mortality analysis was stratified by isolated, multiple, and syndromic case status. RESULTS: The pooled total prevalence of BE was 2.58 per 100,000 total births (95% CI = 2.40, 2.78) for study years 1974 to 2014. Prevalence varied over time with a decreasing trend from 2000 to 2014. The first-week mortality proportion was 3.5, 17.3, and 14.6% among isolated, multiple, and syndromic BE cases, respectively. The majority of first-week mortality occurred on the first day of life among isolated, multiple, and syndromic BE cases. The proportion of first-week deaths was higher among cases reported from programs in Latin America where ETOPFA services were not available. CONCLUSIONS: Prevalence of BE varied by program and showed a decreasing trend from 2000 to -2014. Mortality is a concern among multiple and syndromic cases, and a high proportion of deaths among cases occurred during the first week of life. KEY POINTS: · Total prevalence of BE was 2.58 per 100,000 births.. · Prevalence decreased from 2000 to 2014.. · The first-week mortality was 9.3%.. |
Use of Serial Testing to Interrupt a SARS-CoV-2 Outbreak on a Hospital Medical Floor - Minnesota, October-December 2020.
Prabhu RM , Firestone MJ , Bergman KL , Beaudoin AL , Hale T , Lorentz AJ , Garfin J , Wang X , Holzbauer SM . Infect Control Hosp Epidemiol 2023 44 (3) 427-432 ![]() ![]() OBJECTIVE: Describe a severe acute respiratory coronavirus virus 2 (SARS-CoV-2) hospital outbreak and the role of serial testing of patients and healthcare personnel (HCP) in interrupting SARS-CoV-2 transmission. DESIGN: Outbreak investigation. SETTING: Medical floor of a tertiary-care center in Minnesota. METHODS: Serial testing for SARS-CoV-2 and whole-genome sequencing (WGS) of positive specimens from HCP and patients were used. An outbreak-associated case was defined as a positive SARS-CoV-2 molecular test in an HCP who worked on the floor prior to testing positive or in a patient who was hospitalized on the medical floor bewteen October 27 and December 1, 2020. WGS was used to determine potential routes of transmission. RESULTS: The outbreak was detected after a patient hospitalized for 12 days tested positive for SARS-CoV-2. Serial testing of patients and HCP was conducted in response. Overall, 247 HCP and 41 patients participated in serial SARS-CoV-2 testing; 52 HCP (21%) and 19 hospitalized patients (46%) tested positive. One additional HCP tested positive outside serial testing. The WGS of specimens from 27 (51%) HCP and 15 (79%) patients identified 3 distinct transmission clusters. WGS and epidemiologic evidence suggested intrafacility transmission. The proportions of asymptomatic and presymptomatic patients who tested positive (63%) and HCP who worked during their infectious period (75%) highlight the need for serial testing of asymptomatic patients and HCP during outbreaks. CONCLUSIONS: Coupled with preventive measures such as personal protective equipment use and physical distancing, serial testing of HCP and patients could help detect and prevent transmission within healthcare facilities during outbreaks and when nosocomial transmission is suspected. |
The efficacy and safety of rotavirus vaccines in countries in Africa and Asia with high child mortality
Henschke N , Bergman H , Hungerford D , Cunliffe NA , Grais RF , Kang G , Parashar UD , Wang SA , Neuzil KM . Vaccine 2022 40 (12) 1707-1711 Rotavirus remains a leading cause of diarrhoeal morbidity and mortality in young children and rotavirus vaccines are critical for reducing global disease burden. This report addresses the performance of rotavirus vaccines in countries with high child mortality. We performed a sensitivity analysis as part of a systematic review on rotavirus vaccines to inform development of World Health Organization vaccine recommendations. The efficacy of four prequalified vaccines against severe rotavirus gastroenteritis was similar across high mortality settings in Asia and Africa. Within the first year following vaccination, vaccine efficacy for the four vaccines ranged from 48% to 57% while in the second year, efficacy ranged from 29% to 54%. The four vaccines showed no increase in intussusception risk in these settings. All four vaccines appear to prevent significant numbers of severe rotavirus gastroenteritis episodes with no measurable increase in intussusception risk in high mortality settings in Africa and Asia. |
Medicaid healthcare expenditures for infants with birth defects potentially related to Zika virus infection in North Carolina, 2011-2016
Bergman K , Forestieri NE , Di Bona VL , Grosse SD , Moore CA . Birth Defects Res 2022 114 (2) 80-89 BACKGROUND: In 2016, Zika virus (ZIKV) was recognized as a human teratogen. North Carolina (NC) had no local transmission of ZIKV but infants with relevant birth defects, including severe brain anomalies, microcephaly, and eye abnormalities, require specialized care and services, the costs of which have not yet been quantified. The objective of this study is to examine NC Medicaid healthcare expenditures for infants with defects potentially related to ZIKV compared to infants with no reported defects. METHODS: Data sources for this retrospective cohort study include NC birth certificates, Birth Defects Monitoring Program data, and Medicaid enrollment and paid claims files. Infants with relevant defects were identified and expenditure ratios were calculated to compare distributions of estimated expenditures during the first year of life for infants with relevant defects and infants with no reported defects. RESULTS: This analysis included 551 infants with relevant defects and 365,318 infants with no reported defects born 2011-2016. Mean total expenditure per infant with defects was $69,244 (median $30,544) for the first year. The ratio of these expenditures relative to infants with no reported defects was 14.5. Expenditures for infants with select brain anomalies were greater than those for infants with select eye abnormalities only. CONCLUSIONS: Infants with defects potentially related to ZIKV had substantially higher Medicaid expenditures than infants with no reported defects. These results may be informative in the event of a future outbreak and are a resource for program planning related to care for infants in NC. |
Survival of infants born with esophageal atresia among 24 international birth defects surveillance programs.
Bell JC , Baynam G , Bergman JEH , Bermejo-Sánchez E , Botto LD , Canfield MA , Dastgiri S , Gatt M , Groisman B , Hurtado-Villa P , Kallen K , Khoshnood B , Konrad V , Landau D , Lopez-Camelo JS , Martinez L , Morgan M , Mutchinick OM , Nance AE , Nembhard W , Pierini A , Rissmann A , Shan X , Sipek A , Szabova E , Tagliabue G , Yevtushok LS , Zarante I , Nassar N . Birth Defects Res 2021 113 (12) 945-957 ![]() BACKGROUND: Esophageal atresia (EA) affects around 2.3-2.6 per 10,000 births world-wide. Infants born with this condition require surgical correction soon after birth. Most survival studies of infants with EA are locally or regionally based. We aimed to describe survival across multiple world regions. METHODS: We included infants diagnosed with EA between 1980 and 2015 from 24 birth defects surveillance programs that are members of the International Clearinghouse for Birth Defects Surveillance and Research. We calculated survival as the proportion of liveborn infants alive at 1 month, 1- and 5-years, among all infants with EA, those with isolated EA, those with EA and additional anomalies or EA and a chromosomal anomaly or genetic syndrome. We also investigated trends in survival over the decades, 1980s-2010s. RESULTS: We included 6,466 liveborn infants with EA. Survival was 89.4% (95% CI 88.1-90.5) at 1-month, 84.5% (95% CI 83.0-85.9) at 1-year and 82.7% (95% CI 81.2-84.2) at 5-years. One-month survival for infants with isolated EA (97.1%) was higher than for infants with additional anomalies (89.7%) or infants with chromosomal or genetic syndrome diagnoses (57.3%) with little change at 1- and 5-years. Survival at 1 month improved from the 1980s to the 2010s, by 6.5% for infants with isolated EA and by 21.5% for infants with EA and additional anomalies. CONCLUSIONS: Almost all infants with isolated EA survived to 5 years. Mortality was higher for infants with EA and an additional anomaly, including chromosomal or genetic syndromes. Survival improved from the 1980s, particularly for those with additional anomalies. |
Impact of the COVID-19 pandemic on mental health, access to care, and health disparities in the perinatal period.
Masters GA , Asipenko E , Bergman AL , Person SD , Brenckle L , Moore Simas TA , Ko JY , Robbins CL , Byatt N . J Psychiatr Res 2021 137 126-130 BACKGROUND: The COVID-19 pandemic has affected mental health and created barriers to healthcare. In this study, we sought to elucidate the pandemic's effects on mental health and access to care for perinatal individuals. METHODS: This cross-sectional study of individuals in Massachusetts who were pregnant or up to three months postpartum with a history of depressive symptoms examined associations between demographics and psychiatric symptoms (via validated mental health screening instruments) and the COVID-19 pandemic's effects on mental health and access to care. Chi-square associations and multivariate regression models were used. RESULTS: Of 163 participants, 80.8% perceived increased symptoms of depression and 88.8% of anxiety due to the pandemic. Positive screens for depression, anxiety, and/or PTSD at time of interview, higher education, and income were associated with increased symptoms of depression and anxiety due to the pandemic. Positive screens for depression, anxiety, and/or PTSD were also associated with perceived changes in access to mental healthcare. Compared to non-Hispanic White participants, participants of color (Black, Asian, Multiracial, and/or Hispanic/Latinx) were more likely to report that the pandemic changed their mental healthcare access (aOR:3.25, 95%CI:1.23, 8.59). LIMITATIONS: Limitations included study generalizability, given that participants have a history of depressive symptoms, and cross-sectional design. CONCLUSIONS: The pandemic has increased symptoms of perinatal depression and anxiety and impacted perceived access to care. Self-reported increases in depression and anxiety and changes to healthcare access varied by education, race/ethnicity, income, and positive screens. Understanding these differences is important to address perinatal mental health and provide equitable care. |
A Review of Decontamination Methods for Filtering Facepiece Respirators.
Bergman M , Fisher EM , Heimbuch BK . J Int Soc Respir Prot 2020 37 (2) 71-86 During the current COVID-19 infectious disease pandemic, the demand for NIOSH-approved filtering facepiece respirators (FFR) has exceeded supplies and decontamination and reuse of FFRs has been implemented by various user groups. FFR decontamination and reuse is only intended to be implemented as a crisis capacity strategy. This paper provides a review of decontamination procedures in the published literature and calls attention to their benefits and limitations. In most cases, the data are limited to a few FFR models and a limited number of decontamination cycles. Institutions planning to implement a decontamination method must understand its limitations in terms of the degree of inactivation of the intended mircroorganisms and the treatment's effects on the fit and filtration of the device. A supplement to this publication is available https://www.isrp.com/the-isrp-journal/journal- public-abstracts/1215-vol-37-no-2-2020-supplementary-material |
A multi-country study of prevalence and early childhood mortality among children with omphalocele
Nembhard WN , Bergman JEH , Politis MD , Arteaga-Vázquez J , Bermejo-Sánchez E , Canfield MA , Cragan JD , Dastgiri S , de Walle HEK , Feldkamp ML , Nance A , Gatt M , Groisman B , Hurtado-Villa P , Kallén K , Landau D , Lelong N , Lopez-Camelo J , Martinez L , Morgan M , Pierini A , Rissmann A , Šípek A , Szabova E , Tagliabue G , Wertelecki W , Zarante I , Bakker MK , Kancherla V , Mastroiacovo P . Birth Defects Res 2020 112 (20) 1787-1801 BACKGROUND: Omphalocele is the second most common abdominal birth defect and often occurs with other structural and genetic defects. The objective of this study was to determine omphalocele prevalence, time trends, and mortality during early childhood, by geographical region, and the presence of associated anomalies. METHODS: We conducted a retrospective study with 23 birth defect surveillance systems in 18 countries who are members of the International Clearinghouse for Birth Defects Surveillance and Research that submitted data on cases ascertained from 2000 through 2012, approximately 16 million pregnancies were surveyed that resulted in live births, stillbirths, or elective terminations of pregnancy for fetal anomalies (ETOPFA) and cases with omphalocele were included. Overall prevalence and mortality rates for specific ages were calculated (day of birth, neonatal, infant, and early childhood). We used Kaplan-Meier estimates with 95% confidence intervals (CI) to calculate cumulative mortality and joinpoint regression for time trend analyses. RESULTS: The prevalence of omphalocele was 2.6 per 10,000 births (95% CI: 2.5, 2.7) and showed no temporal change from 2000-2012 (average annual percent change = -0.19%, p = .52). The overall mortality rate was 32.1% (95% CI: 30.2, 34.0). Most deaths occurred during the neonatal period and among children with multiple anomalies or syndromic omphalocele. Prevalence and mortality varied by registry type (e.g., hospital- vs. population-based) and inclusion or exclusion of ETOPFA. CONCLUSIONS: The prevalence of omphalocele showed no temporal change from 2000-2012. Approximately one-third of children with omphalocele did not survive early childhood with most deaths occurring in the neonatal period. |
New respirator performance monitor (RePM) for powered air-purifying respirators
Grinshpun SA , Corey J , Yermakov M , Wu B , Strickland KT , Bergman M , Zhuang Z . J Occup Environ Hyg 2020 17 1-8 Powered air-purifying respirators (PAPRs) that offer protection from particulates are deployed in different workplace environments. Usage of PAPRs by healthcare workers is rapidly increasing; these respirators are often considered the best option in healthcare settings, particularly during public health emergency situations, such as outbreaks of pandemic diseases. At the same time, lack of user training and certain vigorous work activities may lead to a decrease in a respirator's performance. There is a critical need for real-time performance monitoring of respiratory protective devices, including PAPRs. In this effort, a new robust and low-cost real-time performance monitor (RePM) capable of evaluating the protection offered by a PAPR against aerosol particles at a workplace was developed. The new device was evaluated on a manikin and on human subjects against a pair of condensation nuclei counters (P-Trak) used as the reference protection measurement system. The outcome was expressed as a manikin-based protection factor (mPF) and a Simulated Workplace Protection Factor (SWPF) determined while testing on subjects. For the manikin-based testing, the data points collected by the two methods were plotted against each other; a near-perfect correlation was observed with a correlation coefficient of 0.997. This high correlation is particularly remarkable since RePM and condensation particle counter (CPC) measure in different particle size ranges. The data variability increased with increasing mPF. The evaluation on human subjects demonstrated that RePM prototype provided an excellent Sensitivity (96.3% measured on human subjects at a response time of 60 sec) and a Specificity of 100%. The device is believed to be the first of its kind to quantitatively monitor PAPR performance while the wearer is working; it is small, lightweight, and does not interfere with job functions. |
A technique to measure respirator protection factors against aerosol particles in simulated workplace settings using portable instruments
Vo E , Horvatin M , Bergman M , Wu B , Zhuang Z . J Occup Environ Hyg 2020 17 (5) 1-12 The aim of this study was to develop a new method to measure respirator protection factors for aerosol particles using portable instruments while workers conduct their normal work. The portable instruments, including a set of two handheld condensation particle counters (CPCs) and two portable aerosol mobility spectrometers (PAMSs), were evaluated with a set of two reference scanning mobility particle sizers (SMPSs). The portable instruments were mounted to a tactical load-bearing vest or backpack and worn by the test subject while conducting their simulated workplace activities. Simulated workplace protection factors (SWPFs) were measured using human subjects exposed to sodium chloride aerosols at three different steady state concentration levels: low (8x10(3) particles/cm(3)), medium (5x10(4) particles/cm(3)), and high (1x10(5) particles/cm(3)). Eight subjects were required to pass a quantitative fit test before beginning a SWPF test for the respirators. Each SWPF test was performed using a protocol of five exercises for 3 min each: (1) normal breathing while standing; (2) bending at the waist; (3) a simulated laboratory-vessel cleaning motion; (4) slow walking in place; and (5) deep breathing. Two instrument sets (one portable instrument {CPC or PAMS} and one reference SMPS for each set) were used to simultaneously measure the aerosol concentrations outside and inside the respirator. The SWPF was calculated as a ratio of the outside and inside particles. Generally, the overall SWPFs measured with the handheld CPCs had a relatively good agreement with those measured with the reference SMPSs, followed by the PAMSs. Under simulated workplace activities, all handheld CPCs, PAMSs, and the reference SMPSs showed a similar GM SWPF trend, and their GM SWPFs decreased when simulated workplace movements increased. This study demonstrated that the new design of mounting two handheld CPCs in the tactical load-bearing vest or mounting one PAMS unit in the backpack permitted subjects to wear it while performing the simulated workplace activities. The CPC shows potential for measuring SWPFs based on its light weight and lack of major instrument malfunctions. |
Evaluation of species identification and rabies virus characterization among bat rabies cases in the United States
Pieracci EG , Brown JA , Bergman DL , Gilbert A , Wallace RM , Blanton JD , Velasco-Villa A , Morgan CN , Lindquist S , Chipman RB . J Am Vet Med Assoc 2020 256 (1) 77-84 OBJECTIVE: To evaluate species identification and rabies virus (RABV) characterization among samples from bats submitted for rabies testing in the United States and assess whether a standardized approach to specimen selection for RABV characterization could enhance detection of a sentinel event in virus dissemination among bats. SAMPLE: United States public health rabies surveillance system data collected in January 2010 through December 2015. PROCEDURES: The number of rabies-tested bats for which species was reported and the number of RABV-positive samples for which virus characterization would likely provide information regarding introduction of novel RABV variants and translocation and host-shift events were calculated. These specimens were designated as specimens of epizootiological importance (SEIs). Additionally, the estimated test load that public health laboratories could expect if all SEIs underwent RABV characterization was determined. RESULTS: Species was reported for 74,928 of 160,017 (47%) bats submitted for rabies testing. Identified SEIs were grouped in 3 subcategories, namely nonindigenous bats; bats in southern border states, Florida, Puerto Rico, and the US Virgin Islands; and bats of species that are not commonly found to be inflected with RABV. Annually, 692 (95% CI, 600 to 784) SEIs were identified, of which only 295 (95% CI, 148 to 442) underwent virus characterization. Virus characterization of all SEIs would be expected to increase public health laboratories' overall test load by 397 (95% CI, 287 to 506) samples each year. CONCLUSIONS AND CLINICAL RELEVANCE: Species identification and RABV characterization may aid detection of a sentinel event in bat RABV dissemination. With additional resources, RABV characterization of all SEIs as a standardized approach to testing could contribute to knowledge of circulating bat RABV variants. |
Population-based surveillance for birth defects potentially related to Zika virus infection - 22 states and territories, January 2016-June 2017
Smoots AN , Olson SM , Cragan J , Delaney A , Roth NM , Godfred-Cato S , Jones AM , Nahabedian JF 3rd , Fornoff J , Sandidge T , Yazdy MM , Higgins C , Olney RS , Eckert V , Forkner A , Fox DJ , Stolz A , Crawford K , Cho SJ , Knapp M , Ahmed MF , Lake-Burger H , Elmore AL , Langlois P , Breidenbach R , Nance A , Denson L , Caton L , Forestieri N , Bergman K , Humphries BK , Leedom VO , Tran T , Johnston J , Valencia-Prado M , Perez-Gonzalez S , Romitti PA , Fall C , Bryan JM , Barton J , Arias W , St John K , Mann S , Kimura J , Orantes L , Martin B , de Wilde L , Ellis EM , Song Z , Akosa A , Goodroe C , Ellington SR , Tong VT , Gilboa SM , Moore CA , Honein MA . MMWR Morb Mortal Wkly Rep 2020 69 (3) 67-71 Zika virus infection during pregnancy can cause congenital brain and eye abnormalities and is associated with neurodevelopmental abnormalities (1-3). In areas of the United States that experienced local Zika virus transmission, the prevalence of birth defects potentially related to Zika virus infection during pregnancy increased in the second half of 2016 compared with the first half (4). To update the previous report, CDC analyzed population-based surveillance data from 22 states and territories to estimate the prevalence of birth defects potentially related to Zika virus infection, regardless of laboratory evidence of or exposure to Zika virus, among pregnancies completed during January 1, 2016-June 30, 2017. Jurisdictions were categorized as those 1) with widespread local transmission of Zika virus; 2) with limited local transmission of Zika virus; and 3) without local transmission of Zika virus. Among 2,004,630 live births, 3,359 infants and fetuses with birth defects potentially related to Zika virus infection during pregnancy were identified (1.7 per 1,000 live births, 95% confidence interval [CI] = 1.6-1.7). In areas with widespread local Zika virus transmission, the prevalence of birth defects potentially related to Zika virus infection during pregnancy was significantly higher during the quarters comprising July 2016-March 2017 (July-September 2016 = 3.0; October-December 2016 = 4.0; and January-March 2017 = 5.6 per 1,000 live births) compared with the reference period (January-March 2016) (1.3 per 1,000). These findings suggest a fourfold increase (prevalence ratio [PR] = 4.1, 95% CI = 2.1-8.4) in birth defects potentially related to Zika virus in widespread local transmission areas during January-March 2017 compared with that during January-March 2016, with the highest prevalence (7.0 per 1,000 live births) in February 2017. Population-based birth defects surveillance is critical for identifying infants and fetuses with birth defects potentially related to Zika virus regardless of whether Zika virus testing was conducted, especially given the high prevalence of asymptomatic disease. These data can be used to inform follow-up care and services as well as strengthen surveillance. |
Maternal occupational exposure to solvents and gastroschisis in offspring - National Birth Defects Prevention Study 1997-2011
Spinder N , Almli LM , Desrosiers TA , Arnold KE , Bergman JEH , Kromhout H , Boezen HM , de Walle HEK , Rocheleau C , Reefhuis J . Occup Environ Med 2020 77 (3) 172-178 OBJECTIVES: The aim of this study was to assess the association between maternal occupational exposure to solvents and gastroschisis in offspring. METHODS: We used data from the National Birth Defects Prevention Study, a large population-based case-control study of major birth defects conducted in 10 US states from 1997 to 2011. Infants with gastroschisis were ascertained by active birth defects surveillance systems. Control infants without major birth defects were selected from vital records or birth hospital records. Self-reported maternal occupational histories were collected by telephone interview. Industrial hygienists reviewed this information to estimate exposure to aromatic, chlorinated and petroleum-based solvents from 1 month before conception through the first trimester of pregnancy. Cumulative exposure to solvents was estimated for the same period accounting for estimated exposure intensity and frequency, job duration and hours worked per week. ORs and 95% CIs were estimated to assess the association between exposure to any solvents or solvent classes, and gastroschisis risk. RESULTS: Among 879 cases and 7817 controls, the overall prevalence of periconceptional solvent exposure was 7.3% and 7.4%, respectively. Exposure to any solvent versus no exposure to solvents was not associated with gastroschisis after adjusting for maternal age (OR 1.00, 95% CI 0.75 to 1.32), nor was an association noted for solvent classes. There was no exposure-response relationship between estimated cumulative solvent exposure and gastroschisis after adjusting for maternal age. CONCLUSION: Our study found no association between maternal occupational solvent exposure and gastroschisis in offspring. Further research is needed to understand risk factors for gastroschisis. |
Validation of Computational Fluid Dynamics Models for Evaluating Loose-Fitting Powered Air-Purifying Respirators
Bergman M , Lei Z , Xu S , Strickland K , Zhuang Z . Proc 20th Congr Int Ergon Assoc IEA 2018 I Healthc Ergon (2018) 2019 819 176-185 Loose-fitting powered air-purifying respirators (PAPRs) are used in healthcare settings to reduce exposure to high-risk respiratory pathogens. Innovative computational fluid dynamics (CFD) models were developed for evaluating loose-fitting PAPR performance. However, the computational results of the CFD models have not been validated using actual experimental data. Experimental testing to evaluate particle facepiece leakage was performed in a test laboratory using two models of loose-fitting PAPRs. Each model was mounted on a static (non-moving) advanced headform placed in a sodium chloride (NaCl) aerosol test chamber. The headform performed cyclic breathing via connection to a breathing machine. High-efficiency particulate air (HEPA)-filtered air was supplied directly to the PAPR facepiece using laboratory compressed supplied-air regulated with a mass-flow controller. One model was evaluated with six supplied-air flowrates from 50-215 L/min (Lpm) and the other model with six flowrates from 50-205 Lpm. Three different workrates (minute volumes) were evaluated: low (25 Lpm), moderate 46 (Lpm), and high 88 (Lpm). Manikin penetration factor (mPF) was calculated as the ratio of chamber particle concentration to the in-facepiece concentration. Overall, data analyses indicated that the mPF results from the simulations were well correlated with the experimental laboratory data for all data combined (r = 0.88). For data at the three different workrates (high, moderate, low) for both models combined, the r-values were 0.96, 0.97, and 0.77, respectively. The CFD models of the two PAPR models were validated and may be utilized for further research. |
Numerical Simulations of Exhaled Particles from Wearers of Powered Air Purifying Respirators
Xu SS , Lei Z , Zhuang Z , Bergman M . J Int Soc Respir Prot 2019 36 (2) 66-76 In surgical settings, infectious particulate wound contamination is a recognized cause of post-operative infections. Powered air purifying respirators (PAPRs) are worn by healthcare workers for personal protection against contaminated aerosols. Healthcare infection preventionists have expressed concern about the possibility that infectious particles expelled from PAPR exhalation channels could lead to healthcare-associated disease, especially in operative settings where sterile procedural technique is essential. This study used computational fluid dynamics (CFD) modeling to simulate and visualize the distribution of particles exhaled by PAPR wearers. Using CFD simulations, the PAPR inside to outside ratio of particle concentrations was estimated. Also, the effects of particle sizes, supplied-air flow rates, and breathing work rates on outward leakage were evaluated. This simulation study reconstructed a geometrical model of a static median headform wearing a loose-fitting PAPR by capturing a 3D image. We defined a mathematical model for the headform and PAPR system and ran simulations with four particle sizes, three breathing workloads and two supplied-air flow rates (a total 24 configurations; 4×3×2=24) applied on the digital model of the headform and PAPR system. This model accounts for exhaled particles, but not ambient particles. Computed distributions of particles inside and outside the PAPR are displayed. The outward concentration leakage was low at surgical setting, e.g., it was about 9% for a particle size of 0.1 and 1 μm at light breathing and a 205 L/min supplied-air flow rate. The supplied-air flow rates, particle sizes, and breathing workloads had effects on the outward concentration leakage, as the outward concentration leakage increased as particle size decreased, breathing workload increased, and the supplied-air flow rate decreased. The CFD simulations can help to optimize the supplied-air flow rates. When the loose-fitting PAPR is used, exhaled particles with small size (below 1μm), or heavy breathing workloads, may generate a great risk to the sterile field and should be avoided. |
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