Designing Advanced Respiratory Protective Devices for Pandemics: Performance, Mechanism and Future Perspectives identifies emerging and critical issues that directly or indirectly influence the protective performance of Respiratory Protective Devices (RPDs), along with important future research directions. The severity of the COVID-19 pandemic emphasizes the vital role of respiratory protection provided by PPE (and RPD) in novel infectious respiratory disease control. A wealth of recent research on coronavirus mitigation measures is combined with prior information on infectious diseases, RPDs, and human physiological and psychological responses to make this a fundamental resource on recent advances, innovative perspectives on respiratory protection, and new applications. The effectiveness of such disease control measures rely greatly on the performance of the RPD, user compliance, and proper use. Only an interdisciplinary approach to this issue can lead to success.

• Combines introductory material on the nature of infectious disease and mechanisms of respiratory protection with cutting-edge research
• Examines the different material properties that lead to successful RPDs, including breathability, comfort, and recyclability
• Explains different methods for RPD test, evaluation, and approval from regulatory agencies worldwide

Due to their geometry and thermal physiology, hands are most vulnerable to cold weather injuries and loss of dexterity. Gloves are the most common for hand protection during exposure to extreme thermal and hazardous environments. Although glove microclimate properties such as area factor, air gap thickness, and contact area play a significant role in thermal protection, identifying local (at individual hand segments) glove microclimate properties is still a research gap. For the first time, the glove-microclimate properties for 16 hand segments at high spatial resolution were analyzed by employing state-of-the-art hand-held 3D scanner and post-processing techniques for different glove types. Our results clearly indicate that the glove area factor for distal phalanges is significantly higher (by 49.8 %) than that for other hand segments, which increases the heat transfer from distal phalanges. In contrast, average air gap thickness was relatively uniform across all hand segments. The glove type had a pronounced effect on glove microclimate properties, e.g., bulky and heavy cold weather protective gloves had a larger average air gap thickness and glove area factor. Regression models are also developed to estimate the glove microclimate properties from simple measurement (i.e., ease allowance).

Firefighters rely heavily on PPE to shield them from potential injuries and accidents. Among the PPE, firefighting gloves play a crucial role; they are specifically designed to provide robust protection from hand-related injuries while simultaneously ensuring they don’t compromise the wearer’s dexterity and ability to execute diverse manual operations. Hands are uniquely dexterous and have higher needs for motion and function than any other body parts. Besides, hands, especially fingers, have a larger surface-to-volume ratio, making them especially vulnerable to burn or cold injuries. Moreover, the skin of the hand is highly sensitive, with a high concentration of nerve endings that render it capable of detailed sensory perception. The multifaceted characteristics highlight the uniqueness and complexity of the hand, necessitating a tailored and comprehensive approach to glove design that considers all these special features.

However, due to the technological and knowledge gaps, as illustrated in Figure C1, the current designs of these gloves often fit poorly. This ill-fit directly hinders grip strength, dexterity, and tactile sensation, reducing work performance and amplifying the risk of hand injuries. For example, wearing gloves that are too tight can restrict blood flow to the hands, potentially leading to strain, numbness, and increased risk of injuries. On the other hand, gloves that are too loose may interfere with grip and precision, causing a loss in dexterity and manual performance. Chronic use of ill-fitted gloves can lead to longterm issues such as musculoskeletal disorders, nerve compression, and repetitive stress injuries. Firefighters may even remove their gloves to perform tasks due to the poor fit, exposing their hands to dangerous conditions. Alarmingly, data from 2020 in the United States highlights this concern, recording 22,450 firefighter injuries, of which 10% to 12% were injuries to the hands and fingers. This underscores the urgent necessity to reconsider and enhance glove fit for firefighters.

Cold environments pose significant risks to human health, well-being, and productivity, with hands being particularly vulnerable to cold stress and injuries. Mathematical models of hand thermoregulation have emerged as valuable tools for understanding and predicting hand performance and injuries, especially in extreme cold environments. While significant progress has been made in mathematical modeling, a systematic review of these models is currently lacking. This paper aims to fill this knowledge gap by conducting a comprehensive review of the existing literature on hand thermoregulation models in cold environments. It begins with an introduction to the unique thermophysical and thermophysiological characteristics of the hand. It then summarizes the historical evolution of hand thermoregulation models. The essential principles for developing hand-specific thermoregulation models are outlined, encompassing modeling of hand anatomy and geometry, thermophysiological responses, and heat transfer between the hand and its surroundings. This review presents prediction methods for cold injuries and hand performance. The need for future advancements in hand thermoregulation modeling is emphasized. Specifically, achieving a more realistic representation of hand anatomy and geometry, as well as incorporating location-dependent thermophysical properties and physiological behaviors of the hand, are identified as crucial areas for improvement to enhance prediction accuracy. This review will contribute to a deeper understanding of hand thermoregulation mechanisms and their interaction with cold environments, as well as the development of more reliable and applicable models.

Infectious respiratory diseases such as the current COVID-19 have caused public health crises and interfered with social activity. Given the complexity of these novel infectious diseases, their dynamic nature, along with rapid changes in social and occupational environments, technology, and means of interpersonal interaction, respiratory protective devices (RPDs) play a crucial role in controlling infection, particularly for viruses like SARS-CoV-2 that have a high transmission rate, strong viability, multiple infection routes and mechanisms, and emerging new variants that could reduce the efficacy of existing vaccines. Evidence of asymptomatic and pre-symptomatic transmissions further highlights the importance of a universal adoption of RPDs. RPDs have substantially improved over the past 100 years due to advances in technology, materials, and medical knowledge.

All building materials must meet a specific test standard in order to move forward with manufacturing. This standard, the ASTM-E84 Standard Test Method for Surface Burning Characteristics of Building Materials, is used to determine how various materials act upon ignition. It is a costly, complex, and large-scale standard that has been the norm. However, a new method has been introduced, and it’s shaking up how the E84 test is run.

The cone calorimeter is the most widely used instrument to study fire behavior of materials because it provides abundant information with relatively small sized samples. They are rarely found in the United States, but the Laboratories for Functional Textiles and Protective Clothing (LABS) at Iowa State University have acquired one and are looking for building material, furniture material, and insulation material manufacturers who may be interested in a cone calorimeter’s expedited testing capabilities.

Because of the large scale and complexity of the E84, the cone calorimeter can use less of the same material to inform the possibility of passing. This process will save time, resources, and expenses while trying alternative fire retardants for the best performance before attempting the E84 standard.

“Our lab can conduct tests according to many standards,” says lab manager Dr. Rui Li, “but we aren’t certified to provide a certification to the customer. So, we are best suited to offer pre-standard test assurance and customized test services for research and development purposes.”

For more information about the cone calorimeter and other test capabilities offered by LABS, contact Dr. Rui Li at ruili@iastate.edu or visit the LABS website at https://aeshm.hs.iastate.edu/current-students/facilities/laboratories-for-functional-textiles-and-protective-clothing/