Phantom study of a self-shielded X-ray bone age assessment instrument against scattered radiation in children.

Hand-wrist radiography is the most common and accurate method for evaluating children's bone age. To reduce the scattered radiation of radiosensitive organs in bone age assessment, we designed a small X-ray instrument with radioprotection function by adding metal enclosure for X-ray shielding. We used a phantom operator to compare the scattered radiation doses received by sensitive organs under three different protection scenarios (proposed instrument, radiation personal protective equipment, no protection). The proposed instrument showed greater reduction in the mean dose of a single exposure compared with radiation personal protective equipment especially on the left side which was proximal to the X-ray machine (≥80.0% in eye and thyroid, ≥99.9% in breast and gonad). The proposed instrument provides a new pathway towards more convenient and efficient radioprotection.

Determining the filtration effectiveness of non-standard respiratory protective devices by an ad-hoc laboratory methodology.

The recent pandemic caused by COVID-19 profoundly changed people's habits. Wearing a face mask has become usual in everyday life to reduce the risk of infection from airborne diseases. At the beginning of the pandemic, the massive request of surgical or filtering face piece (FFP) masks resulted in a global shortage of these devices for the most exposed people, such as healthcare workers. Due to this high demand for respiratory protective devices, many industrial plants have partly converted to the production of face masks using adapted materials and not complying with any specific regulation (non-standard respiratory protective devices or community masks). In this work, an ad-hoc laboratory methodology has been developed to evaluate the filtration efficiency of the materials that compose the community masks using specific instrumentation. The instrumentation consists of three main tools: an aerosol generator, a specifically designed measuring chamber, and an optical particle sizer (OPS) for the measurement of aerosol concentration. The generated aerosol was sent into the measuring chamber, divided into two separate sections by the respiratory mask. The OPS measured the aerosol mass concentration upstream and downstream of the respiratory mask, and from the concentration difference the filtration efficiency was evaluated. The proposed methodology has been validated by evaluating the particle filtration efficiency (PFE) of certified respiratory masks and was then applied for the evaluation of the filtration efficiency of different types of non-standard or community masks to analyze their effectiveness in protecting from the risk of infection of airborne diseases.

Health effects of filtering facepiece respirators: Systematic review of pulmonary and cardiovascular effects.

Filtering facepiece respirators (FFRs) were introduced to protect the wearer by removing small particles from inspired air. FFRs are now also used to reduce the spread of transmissible agents from the wearer and are worn outside traditional healthcare and other workplaces. The COVID-19 pandemic increased concerns about potential adverse effects on wearers. A PUBMED query retrieved articles through June 2022. Abstracts and selected full-text articles were systematically reviewed by the authors. This article focuses upon cardiopulmonary physiologic effects (e.g., ventilation, CO2 elimination, oxygen uptake, and respiratory control) with emphasis upon current and potential research methods as well as summarizing results. 1985 records were identified, of which only 26% were published before 2020. FFR effects on CO2 elimination appear more likely to be significant than effects on oxygenation or cardiovascular function. While FFRs appear well tolerated by healthy persons, more research is needed for those with pulmonary or cardiac disorders, and for children. Many traditional pulmonary exercise study methods require special care when applied to filtering facepiece respirators. Studying additional parameters may explain the paradox of many subjective discomfort reports despite very limited physiologic effects.

Health effects of filtering facepiece respirators: Research and clinical implications of comfort, thermal, skin, psychologic, and workplace effects.

Filtering facepiece respirators (FFR's) such as N95s have become widely used in appropriate settings for personal respiratory protection and are increasingly used beyond workplace settings. Concerns about possible adverse effects have appeared in many publications, particularly since the COVID-19 pandemic led to much more widespread use. This paper synthesizes known effects based upon review of publications in PubMed since 1995, addressing effects other than pulmonary and cardiovascular (reviewed elsewhere). Findings: (1) Subjective discomfort is very frequently reported; this includes general discomfort or organ-system-specific complaints such as respiratory, headache, dermatologic, and heat. Research methods are widely divergent, and we propose a taxonomy to classify such studies by methodology, study population (subjects, experimental vs. observational methodology, comparator, specificity, and timeframe) to facilitate synthesis. (2) Objective measures of increased heat and humidity within the mask are well documented. (3) Frequency and characteristics of dermatologic effects have been insufficiently evaluated. (4) Physical mask designs are varied, making generalizations challenging. (5) More studies of impact on work performance and communication are needed. (6) Studies of effect of FFR design and accompanying training materials on ease and consistency of use are needed.

Rationale and Design of a Study to Test the Effect of Personal Protective Aids on Hypertension and Diabetes in People Living With High Levels of Air Pollution-Study Protocol.

BACKGROUND: Air pollution is the largest environmental cause of disease and premature death in the world today, disproportionally affecting low- and middle-income countries (LMIC) such as India. Studies have shown that exposure to particulate matter <2.5 µm (PM2.5) can contribute to cardiovascular disease and increase mortality. We hypothesise that the use of personal protective aids (home indoor air purifiers/N95 masks) can decrease systolic blood pressure (SBP) in people with hypertension and decrease fasting blood glucose levels (FBG) in those with diabetes. METHOD: This is a prospective randomised crossover study in Dalkhola, India-an area of high ambient PM2.5 levels. Participants between 18-70 years of age with hypertension (n=128) and diabetes (n=33) will be invited to participate in the study. They will be randomised to either an intervention or control arm for 4 weeks, after which they will cross over to the other arm following a 2-week washout period. The intervention will consist of using an indoor air purifier at night and N95 mask when outdoors. The control period will involve using an identical air purifier and N95 mask with the filter removed (sham filtration). Participants and outcome assessors will be blinded to study arm assignment. OUTCOME EVALUATION: The primary outcome of the study is the absolute reduction in SBP among people with hypertension and absolute reduction in FBG among people with diabetes. DISCUSSION: This is the first randomised controlled trial to evaluate the use of personal protective aids as a therapeutic measure in people with hypertension and diabetes exposed to high levels of PM2.5. Given the high burden of air pollution in LMIC, there is an urgent need for adaptation measures targeting people at high risk for mortality from this exposure. The results of our study will demonstrate whether personal protective aids can be a viable adaptation measure for people living with hypertension and diabetes in areas with a high burden of air pollution. TRIAL REGISTRATION: This is clinicaltrials.gov Identifier: NCT04854187.

[Research on the protective effect of hearing protective device for workers exposed to noise in a motor manufacturing enterprise].

Objective: To understand the current situation of noise hazard in a motor manufacturing enterprise, and to explore the protective effect of workers wearing hearing protective device and its possible influencing factors. Methods: In November 2021, a total of 179 noise workers wearing hearing protective devices in a motor manufacturing company in a city were selected as research objects. Personal attenuation rating (PAR) of workers wearing hearing protective devices was measured. Baseline PAR was analyzed for different subgroups of basic demographic information, noise exposure, and the use of hearing protective devices to evaluate the effect of the intervention. Baseline PAR was compared using nonparametric tests. Results: There were 179 workers from 35 positions in 4 types of work, and the over-standard noise rate was 51.2% (42/82), among which the noise exposure intensity of motor equipment debugging workers was the highest [94.4 dB (A) ]. Compared the baseline PAR of different characteristics, it was found that the baseline PAR of male workers, workers whose daily noise exposure time were <8 h, workers who had used the hearing protective devices for 10 to 14 years, and workers who thought the hearing protective devices were comfortable were all higher, and the differences were statistically significant (P<0.05). Baseline PAR passing rate was 43.0% (77/179), and PAR of 102 workers who did not pass baseline test increased from 0 (0, 3) dB before intervention to 14 (12, 16) dB after intervention, with statistical significance (P<0.05) . Conclusion: The noise hazard in this motor manufacturing enterprise is serious, and the protective effect of workers wearing hearing protective devices is not good. Gender, daily noise exposure time, years and comfort of wearing hearing protective device are the possible influencing factors of poor protective effect.

Joint optimization of mission abort and protective device selection policies for multistate systems.

For safety-critical systems such as aircrafts and submarines, mission abort is commonly deployed to enhance system survivability at the cost of reducing mission success probability. In addition to mission abort, protective device can also mitigate the failure risk of safety-critical systems by reducing the magnitude of external shocks. Considering the effect of protective device on system failure behavior, this article proposes a condition-based mission abort policy where a mission is terminated and rescue procedure starts immediately if the state of system is worse than a control limit. Based on the developed mission abort policy, mission reliability and system survivability are evaluated to analyze the risk of mission failure and system failure. The optimal mission abort threshold balancing the tradeoff between mission reliability and system survivability is investigated. Furthermore, the joint optimization of mission abort and protective device selection policies is explored by simultaneously optimizing the defensive factor and abort threshold. A numerical example on a hydraulic system is presented to illustrate the applicability of the proposed policies.

Using infrared imaging and deep learning in fit-checking of respiratory protective devices among healthcare professionals.

AIMS: This study aimed to investigate the application of infrared thermal imaging and adopt deep learning to detect air leakage for determining the fitness of respirators during fit-checks. BACKGROUND: The outbreak of Covid-19 virus constitutes a public health crisis with substantial resultant morbidities and mortalities; has exerted profound impacts. METHODS: This was a prospective observational study, employing a non-probability sampling method on a convenience sample to recruit the participants and followed the Strengthening the Reporting of Observational Studies in Epidemiology statement guidelines. RESULTS: The use of infrared thermal imaging identified air leakage points as a disruption to the facial thermal pattern distribution at (a) front of face; (b) right lateral of the face; (c) left lateral of the face; (d) top of the facemask with the head facing down; and (e) bottom of the facemask with the head facing up. Results also indicated that artificial intelligence tools and the proliferation of deep learning have the potential to detect the location of air leakage locations. CONCLUSION: The use of infrared thermal imaging provides evidence of the feasibility and applicability of infrared thermal imaging techniques in detecting air leakage for individuals wearing respirators. CLINICAL RELEVANCE: The use of infrared thermal technology can serve a potential role in complement fit-checking of respiratory protective devices and offers promising practical utility in determining the fitness of respirators for nurses at the frontline to protect against the air-borne viruses.

[Risk assessment on noise-induced hearing loss of 488 workers in a petrochemical plant].

Objective: To assess the risk of noise-induced hearing loss in workers from a petrochemical plant. Methods: In October 2020, 488 male workers exposed to noise in a petrochemical plant in Guangdong Province were selected by cluster sampling. Acoustics-Estimation of Noise-Induced Hearing Loss (ISO 1999: 2013) was used to assess the risk of noise-induced hearing loss of workers, and individual fit testing was used to evaluate the sound attenuation obtained by the workers. The risk assessment results and fitness test results of workers with different hearing levels were compared. Results: The average noise exposure equivalent sound level of the workers in the petrochemical plant was 86.7 dB (A) . The median of PARs (personal attenuation ratings) was 16 (4, 23) dB. There were statistically significant differences in age and service years among workers with different hearing results (P<0.05) , but no statistically significant differences in noise intensity and PARs (P>0.05) . According to risk assessment results of ISO 1999: 2013, the current risk of high-frequency hearing loss in 488 workers were negligible risk and acceptable risk. The risk of noise-induced deafness weredivided into three levels: negligible risk in 452 workers (92.7%) , medium risk in 27 workers (5.5%) and high risk in 9 workers (1.8%) . The risk of high-frequency hearing loss in next 5 to 15 years for workers with noise exposure level of >94 to 97 dB and >97 dB or above would be medium risk or above. The risk of noise-induced deafness in next 5 to 15 years for workers exposed to noise withlevel of 91 to 94 dB would be medium risk or above. Conclusion: The risk of noise-induced hearing loss in workers from the petrochemical plant is high in next 5 to 15 years, and noise prevention and control measures need to be strengthened. ISO1999: 2013 assessment method may underestimate the risk of hearing loss among workers.

Comparison of ISO work of breathing and NIOSH breathing resistance measurements for air-purifying respirators.

The National Institute for Occupational Safety and Health's methods and requirements for air-purifying respirator breathing resistance in 42 CFR Part 84 do not include work of breathing. The International Organization for Standardization Technical Committee 94, Subcommittee 15 utilized work of breathing to evaluate airflow resistance for all classes of respiratory protective devices as part of their development of performance standards regarding respiratory protective devices. The objectives of this study were: (1) to evaluate the relationship between the International Organization for Standardization's work of breathing measurements and the National Institute for Occupational Safety and Health's breathing resistance test results; (2) to provide scientific bases for standard development organizations to decide if work of breathing should be adopted; and (3) to establish regression equations for manufacturers and test laboratories to estimate work of breathing measurements using breathing resistance data. A total of 43 respirators were tested for work of breathing at minute ventilation rates of 10, 35, 65, 105, and 135 liters per minute. Breathing resistance obtained at a constant flow rate of 85 liters per minute per National Institute of Occupational Safety and Health protocol was correlated to each of the parameters (total work of breathing, inhalation, and exhalation) obtained from the work of breathing tests. The ratio of work of breathing exhalation to work of breathing inhalation for all air-purifying respirators is similar to the ratio of exhalation to inhalation resistance when tested individually. The ratios were about 0.8 for filtering facepiece respirators, 0.5 for half-masks, and 0.25 for full-facepiece respirators. The National Institute for Occupational Safety and Health's breathing resistance is close to work of breathing's minute ventilation of 35 liters per minute, which represents the common walking/working pace in most workplaces. The work of breathing and the National Institute of Occupational Safety and Health's breathing resistance were found to be strongly and positively correlated (r values of 0.7-0.9) at each work rate for inhalation and exhalation. In addition, linear and multiple regression models (R-squared values of 0.5-0.8) were also established to estimate work of breathing using breathing resistance. Work of breathing was correlated higher to breathing resistance for full-facepiece and half-mask elastomeric respirators than filtering facepiece respirators for inhalation. For exhalation, filtering facepiece respirators were correlated much better than full-facepiece and half-mask elastomeric respirators. Therefore, the National Institute for Occupational Safety and Health's breathing resistance may reasonably be used to predict work of breathing for air-purifying respirators. The results could also be used by manufacturers for product development and evaluation.

Acceleration Magnitude at Impact Following Loss of Balance Can Be Estimated Using Deep Learning Model.

Pre-impact fall detection can detect a fall before a body segment hits the ground. When it is integrated with a protective system, it can directly prevent an injury due to hitting the ground. An impact acceleration peak magnitude is one of key measurement factors that can affect the severity of an injury. It can be used as a design parameter for wearable protective devices to prevent injuries. In our study, a novel method is proposed to predict an impact acceleration magnitude after loss of balance using a single inertial measurement unit (IMU) sensor and a sequential-based deep learning model. Twenty-four healthy participants participated in this study for fall experiments. Each participant worn a single IMU sensor on the waist to collect tri-axial accelerometer and angular velocity data. A deep learning method, bi-directional long short-term memory (LSTM) regression, is applied to predict a fall's impact acceleration magnitude prior to fall impact (a fall in five directions). To improve prediction performance, a data augmentation technique with increment of dataset is applied. Our proposed model showed a mean absolute percentage error (MAPE) of 6.69 ± 0.33% with r value of 0.93 when all three different types of data augmentation techniques are applied. Additionally, there was a significant reduction of MAPE by 45.2% when the number of training datasets was increased by 4-fold. These results show that impact acceleration magnitude can be used as an activation parameter for fall prevention such as in a wearable airbag system by optimizing deployment process to minimize fall injury in real time.

A Low-Cost Surge Current Detection Sensor with Predictive Lifetime Display Function for Maintenance of Surge Protective Devices.

In this study, a low-cost surge current detection sensor (SCDS) that can measure high current surges using a low-current toroidal coil is proposed for maintenance of a surge protective device (SPD). The proposed SCDS is designed to display the predicted lifetime of the SPD based on the magnitude of surge current and number of surges. In addition, a method for measuring high surge current using a toroidal coil that can usually measure only low current is proposed. A lightning strike counter consists of a microcontroller with a low-power liquid crystal display (LCD) driver, 3 VDC lithium battery, and signal conditioning circuit that converts amplitude information of the surge current into duration information of a negative pulse to facilitate processing in the microcontroller. In this paper, we propose a software algorithm that can calculate the remaining lifetime of SPD based on the amplitude and number of surge currents. There is also an option to select the capacity of the surge protective device and the number of phase lines, allowing it to assess the predicted lifetime for various types of Class II SPDs. The proposed SCDS is measured as 7.2 µA from the battery power consumption test, and the service life is calculated to be 11.1 years. It meets the International Standard IEC62561-6 test conditions of the lightning strike counter and is expected to be useful in the maintenance of SPDs and lightning protection systems.

[Reduction of Radiation Exposure to Operator with Radiation Protective Device in ERCP Procedure Using Over-coach X-ray TV System].

It is important to reduce the dose received by medical staffs. The purpose of this study was to evaluate the effect of protective curtain and the property of small optically stimulated luminescence (OSL) dosimeters used for ambient dose measurement in fluoroscopy. The property of small OSL dosimeters was investigated in terms of uniformity, changing fluoroscopy time and polymethyl methacrylate (PMMA) thickness, and angular dependence. Paper pipes were assembled in glid shape and ambient dose was investigated by using small OSL dosimeters that were put on them with and without protective curtain. Air kerma was investigated by small OSL dosimeters that were put on a head phantom at the position of eyes. Dose response of small OSL dosimeters was independent of fluoroscopy time and PMMA thickness, so it is appropriate to measure ambient dose by small OSL dosimeters. In relation to ambient dose, there was significant difference with and without protective curtain (p<0.001, paired-t-test). These air kerma on the head phantom were reduced to approximately 20% by attaching protective curtain. In order to reduce the dose received by operators, it is desirable to use protective curtain.

The fastest field sport in the world: A case report on 3-dimensional printed hurling gloves to help prevent injury.

STUDY DESIGN: Case series. INTRODUCTION: Hand injuries are the most common injury observed in hurling although compliance in wearing protective gloves is reportedly low. PURPOSE OF THE STUDY: To devise a glove that offers comfort, protection and freedom of movement, using the bespoke capabilities of 3-dimensional (3D) printing. METHODS: Each player's "catching" hand was imaged using a 3D scanner to produce a bespoke glove that they later trialed and provided feedback. RESULTS: Nine players provided feedback. On average, the players favorably rated the glove for the protection offered. The average response on comfort was poor, and no players reported that glove aided performance during play. DISCUSSION: This feasibility study explores the versatility of 3D printing as a potential avenue to improve player compliance in wearing protective sportswear. Feedback will help refine glove design for future prototypes. CONCLUSIONS: Hurling is the primary focus in this study, but knowledge gains should be transferable to other sports that have a high incidence of hand injury. LEVEL OF EVIDENCE: 4.

Child cyclists: A study of factors affecting their safety.

AIM: To study various factors that contribute to a child cyclist's risk of having, or being injured in the event of, an accident. METHODS: All children aged 8-12 years, attending four primary schools, who had access to a bicycle were invited to participate. The study consisted of: a questionnaire; a helmet and bicycle check (by professional cycle shop staff) and a practical assessment. RESULTS: Two hundred and ninety-three children participated in one or more parts of the study. Of the 214 helmets checked, 41% were deemed 'unsafe'. Forty-one percent of 205 bicycles checked were not considered roadworthy. Of the 127 children who usually ride their bicycle to school, 59% had either a bicycle that was not considered roadworthy or a helmet that was judged 'unsafe'. Of the 200 children, 91% knew the correct hand signals for a right and left turn. Eleven- and 12-year-olds were significantly better at performing the practical assessment than 8- to 10-year-olds (P < 0.0001). CONCLUSIONS: Parents cannot assume that simply providing a cycle helmet and ensuring it is worn means a child will have maximum protection in the event of an accident. Calculations that base the safety benefits of cycle helmets on observation studies are likely to be underestimates. Regular checking of the roadworthiness of a child's bicycle is advised as simple things such as underinflated tyres or worn brake pads can adversely affect handling. There is no specific age at which it can be said a young child is 'safe' to ride unaccompanied on public roads.

Reduction Method of Operator and Medical Staff Radiation Exposure in Balloon Pulmonary Angioplasty for Chronic Thromboembolic Pulmonary Hypertension.

The purpose of this study is to investigate a reduction method of radiation exposure for operator and medical staff in balloon pulmonary angioplasty (BPA) for chronic thromboembolic pulmonary hypertension (CTEPH). We devised a new radiation protection, which is U-shaped acrylic supporting table with 0.35 mmPb unleaded radiation protection sheet. A human phantom was put on the bed of cardiac angiography system [C-arm angulation: posteroanterior (PA), L-arm angulation: left anterior oblique (LAO) 60°]. The ambient equivalent dose rate was measured under fluoroscopy with and without three radiation protections: U-shaped acrylic supporting table with 0.35 mmPb unleaded radiation protection sheet, radiation protection for the lower body, and radiation protection for the upper body. With the three radiation protections, the ambient equivalent dose rate was decreased more than 99% at the height of 100 cm above the floor at the operator position (PA: from 186.2 µSv/h to 0.5 µSv/h, LAO 60°: from 350.4 µSv/h to 1.6 µSv/h). Ambient equivalent dose rate at the other points are also decreased effectively. The devised dose reduction method can reduce operator and medical staff radiation exposure effectively and be set up without interference for BPA procedure.

Trauma in children due to wheeled recreational devices.

AIM: The aim of this study was to describe trauma in children secondary to the use of wheeled recreational devices (WRDs). METHODS: This study retrospectively described trauma secondary to use of WRDs sustained by children 16 years or younger over a period of 12 months at two tertiary paediatric hospitals in Brisbane, Queensland. Data were analysed from the Paediatric Trauma Registry at these two facilities. Data were also retrieved from The Commission for Children and Young People and Child Guardian to provide information regarding deaths in Queensland from the use of WRDs for the period January 2004 to September 2013. Outcome measures included age, gender, types of injuries, Injury Severity Scores, admission to Intensive Care, and length of hospital stay for all hospital admissions greater than 24 h. RESULTS: A total number of 45 children were admitted with trauma relating to WRDs during the 12 months, representing 5.3% of all trauma admissions of greater than 24 h during this time period. Of these, 34 were male with a median age of 11.0 years (IQR = 9-13). Limbs accounted for the majority (54.5%) of injuries, with other common injuries being spine/cranial fractures (14.5%), lacerations (12.7%), internal organ injuries (9.1%), and intracranial bleeds (9.1%). There were six admissions to the Paediatric Intensive Care Unit and one death. CONCLUSIONS: WRDs contribute significantly to injuries sustained by children. A large proportion of these injuries may be preventable, suggesting that mandating the use of protective equipment in Queensland may be of great benefit.

Design and application of the intraoperative protective device for patients undergoing interventional therapy via the femoral artery approach.

BACKGROUND: Femoral artery puncture is still the most used surgical approach. Because the operation requires local anaesthesia, the patient may not be able to exert full self-control, and their upper and lower limbs and trunk need to be constrained by a protection device. OBJECTIVE: To explore the safe application effect of a new type of anti-movement protection device for upper and lower extremities, shoulders and chest in patients undergoing interventional therapy via the femoral artery approach. METHODS: This is a prospective randomised controlled study. A total of 230 patients were randomly divided into two groups: the study group (n= 115) and the control group (n= 115). The time needed to implement the restraint operation and the loosening of the restraint device in the two groups was recorded, and the satisfaction of surgeons and nurses was investigated. RESULTS: The time needed to perform restraint operation in the study group was significantly less than that in the control group (4.06 ± 0.61 min vs. 7.01 ± 0.76 min, P< 0.05). The satisfaction of surgeons and nurses with the use of the new protective device was significantly better than that of the conventional restraint band (P< 0.05). CONCLUSION: The new anti-movement protection device for upper and lower limbs, shoulders and chest can conveniently and quickly achieve effective protection and braking of patients, ensure the safety of surgery and improve satisfaction.

Validation of krypton as a new tracer gas for the standardization tests of collective and individual protection systems.

Sulfur hexafluoride (SF6) is the reference tracer gas in many international standards for characterizing respiratory protective devices (RPD), fume cupboards, building ventilations, and other installations. However, due to its significant impact on global warming, its use is becoming increasingly restrictive. Krypton 84 (Kr) was chosen to be a possible replacement based on theoretical and practical criteria for the properties that a substitute gas should possess. While compliance with these criteria is generally sufficient to guarantee the reliability of the choice, it is essential in the case of widespread use such as a standard to validate experimentally that this tracer has the same behavior as SF6. In this regard, numerous tests have been carried out to characterize the face leakage of RPD and the rupture of containment of fume cupboards performance tests under different operating conditions. The results obtained are identical with both tracers and lead us to propose the use of Kr as a new reference gas in standards for which SF6 was used.

Using the Number of N95® Filtering Facepiece Respirator Models as an Indicator of Supply Chain Stability in a US Health-Care System.

OBJECTIVES: Personal protective equipment (PPE) supply chain disruptions force US health-care entities to adopt conservation strategies such as procurement from different respirator manufacturers. This research seeks to better understand how the number of respirator models on hand can serve as an indicator of N95 filtering facepiece respirator (FFR) supply chain stability or disruption. METHODS: Researchers looked at differences in the mean number of N95 FFR models, averaged weekly, from 10 hospitals in a health-care system over 15 wk from June 1 to September 10, 2020. Participating hospitals entered near-daily PPE inventory data by manufacturer and model number. RESULTS: A linear mixed effect model was run in SPSS v. 26 using a random intercept for hospitals, with week as a fixed predictor and mean number of respirator models (averaged weekly) on hand as the dependent variable. Each week showed a small but significant effect compared with the past week (P < 0.001), where the average weekly number of respirator models on hand decreased. CONCLUSIONS: The limited data may indicate a resolution of supply chain disruptions and warrant further investigation. Consequently, the number of respirator models may be applicable as an indicator of supply chain stability and be more easily ascertained and tracked by health-care entities.