Relationship between novel design modifications and heat stress relief in structural firefighters' protective clothing

An antimicrobial zinc ion fiber for COVID-19 prevention in nonwoven face coverings for healthcare settings

The COVID-19 pandemic created an unprecedented increase in the usage of personal protective equipment (PPE) in the healthcare industry, especially in the form of face coverings. Subsequently, guidelines related to breathability and wear comfort were published by the Centers for Disease Control (CDC) as an influx of various new materials entered the PPE market. This study evaluated a proprietary, novel, zinc-ion embedded fiber with the ability to deactivate bacteria and viruses, including SARS-COV-2, for its wear comfort in a nonwoven disposable mask in comparison to a commercially available surgical face mask which served as the control. Ten healthy, full-time, career, firefighters participated in this study wearing both masks in a randomized fashion. A medical task simulation (MTS) protocol was developed to replicate nursing task metabolic rates, per the compendium of physical activities, via a graded treadmill walking exercise. Participant ratings including ease of mask fit, overall mask comfort, facial comfort, breathability, and facial temperature sensation were recorded before, during, and after the 50-minute protocol in a controlled environmental chamber. The 100% nylon, zinc ion mask was rated as slightly cooler at the beginning of the trial (at 0.8 vs. 1.3), than the commercially available polypropylene mask. The polypropylene mask also reached a perceived mask facial comfort (MFC) rating of 1.6 just 35 min into the protocol whereas the zinc ion mask did not reach a rating of slight discomfort until the end of the exercise. Findings indicate the novel zinc-ion embedded mask was as comfortable, if not more so, than the commercially available nonwoven mask with more favorable ratings for longer durations. Not only do the zinc properties provide enhanced protection, but they maintain, if not improve, wearer comfort.

Heat strain of Japanese firefighters wearing personal protective equipment: a review for developing a test method

The aim of this review was to develop a test method for the evaluation of heat strain for structural firefighters wearing personal protective equipment (PPE) in Japan. We analysed a series of our laboratory's questionnaires and experimental studies and reviewed international standards on test methods. We investigated the actual average working conditions (total firefighting time on one incidence, working time with full PPE, maximum temperature and humidity during firefighting) at structural firefighting site in Japan by conducting a large-scale questionnaire survey of Japanese firefighters. We discussed test subjects (firefighters vs. non-firefighters; body size; physical fitness), exercise intensity (absolutes vs. relative; light vs. heavy) and duration, experimental temperature and relative humidity, experimental clothing items including station uniforms (shorts vs. long), and measurement variables (physiological and subjective responses), and suggested a standard test method to evaluate the heat strain of firefighters in hot and humid environments.Practitioner summary: We reviewed studies on human wear trials of firefighting personal protective equipment (PPE) in hot environments and suggested a standard test method to evaluate the heat strain of firefighters. The test method can be internationally utilised to examine the comfort functions and heat stress of PPE in hot, humid environments.

Exploring First Responders' Use and Perceptions on Continuous Health and Environmental Monitoring

First responders lose their lives in the line of duty each year, and many of these deaths result from strenuous physical exertion and exposure to harmful environmental agents. Continuous health monitoring may detect diseases and alert the first responder when vital signs are reaching critical levels. However, continuous monitoring must be acceptable to first responders. The purpose of this study was to discover first responders' current use of wearable technology, their perceptions of what health and environmental indicators should be monitored, and who should be permitted to monitor them. The survey was sent to 645 first responders employed by 24 local fire department stations. A total of 115 (17.8%) first responders answered the survey and 112 were used for analysis. Results found first responders perceived a need for health and environmental monitoring. The health and environmental indicators that respondents perceived as most important for monitoring in the field were heart rate (98.2%) and carbon monoxide (100%), respectively. Overall, using and wearing monitoring devices was not age-dependent and health and environmental concerns were important for first responders at any stage of their career. However, current wearable technology does not seem to be a viable solution for first responders due to device expense and durability issues.

The effects of personal protective equipment on heart rate, oxygen consumption and body temperature of firefighters: A systematic review

BACKGROUND

Fire extinguishing operations are carried out by firefighters equipped with personal protective equipment (PPE) in dangerous environments. Although PPE protects firefighters, it can affect many physiological parameters.

OBJECTIVE

This study aimed to investigate the effects of PPE on firefighters' heart rate (HR), oxygen consumption (OC) and body temperature (BT).

METHODS

This systematic review thoroughly reviewed relevant articles in the reliable databases "Web of Science", "Embase", "IranDoc", "IranMedex", "SID", "Magiran", "Google Scholar", "PubMed" and "Scopus" from 2010 to 2021. Some of the used search terms were "firefighters", "personal protective equipment", "heart rate" and "oxygen consumption".

RESULTS

Out of the 405 studies identified through the systematic search, 18 articles were eligible according to the Joanna Briggs Institute (JBI) checklist, among which 11 studies were conducted in North America, three in Asia, two in Europe, and two studies in Oceania. According to the review of studies, PPE increased HR, BT, and OC. The type of PPE components, the weight of the equipment, the kind of activity of firefighters, and weather conditions were among the influencing parameters on the extent of PPE's influence on these physiological parameters.

CONCLUSION

The results of the studies show that PPE separately and collectively affects the physiological parameters of HR, BT and OC. To reduce these effects, it is necessary to pay attention to several items, including the weight of PPE, the type of PPE ingredients in different weather conditions, and the type of activities of firefighters in PPE design.

Combining multiple human physiological signals using fuzzy logic to determine stress caused by battle dress uniforms

Abstract

This study presents a novel stress index for clothing using physiological signals to estimate stress induced by battle dress uniforms (BDU) during physical activity. The approach uses a fuzzy logic-based nonlinear mapping to compute the stress from physiological signals. Ten healthy men performed a battery of physical activities in a controlled environment. Heart rate (HR), respiration rate (RR), skin temperature (ST), and galvanic skin response (GSR) were measured continuously for the participants during activity wearing three kinds of clothing (two BDUs and a control garment). The individual physiological responses were combined using a fuzzy-logic system to derive a stress measure called Clothed Activity Stress Index (CASI). Repeated measures ANOVA showed that the garments significantly (α = .05) affected the HR (p < .001) and RR (p < .001). In addition, interactions between the activity and garment were significant for HR, RR, and ST (p < .001, p < .001, p < .036). The physiological measures differed significantly between rest and activity for the two uniforms. The stress indices (ranging between 0 and 1) during rest and activity were 0.24 and 0.35 for control, 0.27 and 0.43 for BDU-1, and 0.33 and 0.44 for BDU-2. It is shown here that clothing systems impact human stress levels to a measurable level. This computational approach is applicable to measure stress caused by protective wear under different operational conditions and can be suitable for sports and combat gears.

Article Highlights

Influence of different protection levels of PPE on nurses' physical fatigue during the COVID-19 pandemic

BACKGROUND

The continuous spread of COVID-19 globally has led to busier medical practices and nurses are having to provide medical services to patients while suffering from high levels of fatigue.

OBJECTIVE

This study experimentally investigated the influence of different levels of personal protection equipment (PPE) on nurses' physical fatigue.

METHODS

We collected data from 12 participants by simulating a series of nursing tasks. The participants wore one of three different protection levels of PPE, and data recording their heart rate (HR), oral temperature, task completion time, and subjective fatigue were collected. Following this, relationship models between subjective fatigue and objective fatigue indices was established using multiple linear regression analysis.

RESULTS

By analyzing the variation trends of single indices of HR, oral temperature, task completion time, and subjective fatigue, it was found that the higher the level of protection levels of PPE worn by the participants, the higher the degree of fatigue experienced by them. In addition, taking subjective fatigue variation as the dependent variable and objective fatigue indices as independent variables, relationship models of the three different protection levels of PPE were established.

CONCLUSIONS

The results confirmed the influence of different protection levels of PPE on nurses' physical fatigue levels. They also provide a basis for medical administrators to monitor the degree of fatigue experienced by nurses, attempt to arrange nurses' work content accordingly, and schedule suitably to combat and manage recorded increases in fatigue.

Relationship between Heat Loss Indexes and Physiological Indicators of Turnout Related Heat Strain in Mild and Hot Environments

A validated physiological manikin method was used to qualify environmentally dependent correlations between firefighter turnout THL (total heat loss) and R_ef (intrinsic evaporative resistance) heat strain indexes and core temperature rise in stressful work conducted in mild (25 °C, 65% RH) and in hot (35 °C, 40% RH; 40 °C, 28% RH) conditions. Five turnout suit constructions representing a wide range of breathability were selected. The observed correlations between measured material heat loss and core temperature showed that the THL heat strain index accurately forecast thermal burden in mild environments (< 25 °C); while the R_ef index provided accurate prediction in hot environments (> 35 °C). They showed that the THL index did not predict heat strain in hot work environments. The findings of this study support incorporating both the R_ef and THL heat strain indexes as dual metrics for characterizing the heat strain performance of turnout clothing fabrics.

Preventing and Monitoring Work-Related Diseases in Firefighters: A Literature Review on Sensor-Based Systems and Future Perspectives in Robotic Devices

In recent years, the necessity to prevent work-related diseases has led to the use of sensor-based systems to measure important features during working activities. This topic achieved great popularity especially in hazardous and demanding activities such as those required of firefighters. Among feasible sensor systems, wearable sensors revealed their advantages in terms of possibility to conduct measures in real conditions and without influencing the movements of workers. In addition, the advent of robotics can be also exploited in order to reduce work-related disorders. The present literature review aims at providing an overview of sensor-based systems used to monitor physiological and physical parameters in firefighters during real activities, as well as to offer ideas for understanding the potentialities of exoskeletons and assistive devices.

A pilot study of core body temperatures in healthcare workers wearing personal protective equipment in a high-level isolation unit

Personal protective equipment used by healthcare workers to mitigate disease transmission risks while caring for patients with high-consequence infectious diseases can impair normal body cooling mechanisms and exacerbate physiological strain. Symptoms of heat strain (e.g., cognitive impairment, confusion, muscle cramping) are especially harmful in the high-risk environment of high-consequence infectious disease care. In this pilot study, the core body temperatures of healthcare workers were assessed using an ingestible, wireless-transmission thermometer while performing patient care tasks common to a high-level isolation unit setting in powered air purifying respirator (PAPR)-level. The objective was to determine the potential for occupational health hazard due to heat stress in an environmentally controlled unit. Maximum core temperatures of the six participants ranged from 37.4 °C (99.3 °F) to 39.9 °C (103.8°F) during the 4-hr shift; core temperatures of half (n = 3) of the participants exceeded 38.5 °C (101.3 °F), the upper core temperature limit. Future investigations are needed to identify other heat stress risks both in and outside of controlled units. The ongoing COVID-19 pandemic offers unique opportunities for field-based research on risks of heat stress related to personal protective equipment in healthcare workers that can lead to both short- and long-term innovations in this field.

Heat Safety in the Workplace: Modified Delphi Consensus to Establish Strategies and Resources to Protect the US Workers

The purpose of this consensus document was to develop feasible, evidence-based occupational heat safety recommendations to protect the US workers that experience heat stress. Heat safety recommendations were created to protect worker health and to avoid productivity losses associated with occupational heat stress. Recommendations were tailored to be utilized by safety managers, industrial hygienists, and the employers who bear responsibility for implementing heat safety plans. An interdisciplinary roundtable comprised of 51 experts was assembled to create a narrative review summarizing current data and gaps in knowledge within eight heat safety topics: (a) heat hygiene, (b) hydration, (c) heat acclimatization, (d) environmental monitoring, (e) physiological monitoring, (f) body cooling, (g) textiles and personal protective gear, and (h) emergency action plan implementation. The consensus-based recommendations for each topic were created using the Delphi method and evaluated based on scientific evidence, feasibility, and clarity. The current document presents 40 occupational heat safety recommendations across all eight topics. Establishing these recommendations will help organizations and employers create effective heat safety plans for their workplaces, address factors that limit the implementation of heat safety best-practices and protect worker health and productivity.

Effects of firefighting hood design, laundering and doffing on smoke protection, heat stress and wearability

Firefighter hoods must provide protection from elevated temperatures and products of combustion (e.g. particulate) while simultaneously being wearable (comfortable and not interfering with firefighting activities). The purpose of this study was to quantify the impact of (1) hood design (traditional knit hood vs particulate-blocking hood), (2) repeated laundering, and (3) hood removal method (traditional vs overhead doffing) on (a) protection from soot contamination on the neck, (b) heat stress and (c) wearability measures. Using a fireground exposure simulator, 24 firefighters performed firefighting activities in realistic smoke and heat conditions using a new knit hood, new particulate-blocking hood and laundered particulate-blocking hood. Overall, soot contamination levels measured from neck skin were lower when wearing the laundered particulate-blocking hoods compared to new knit hoods, and when using the overhead hood removal process. No significant differences in skin temperature, core temperature, heart rate or wearability measures were found between the hood conditions. Practitioner Summary: The addition of a particulate-blocking layer to firefighters' traditional two-ply hood was found to reduce the PAH contamination reaching the neck but did not affect heat stress measurements or thermal perceptions. Modifying the process for hood removal resulted in a larger reduction in neck skin contamination than design modification. Abbreviations: ANOVA: analysis of variance; B: new particulate-blocking hood and PPE (PPE configuration); FES: fireground exposure simulator; GI: gastrointestinal; K: new knit hood and PPE (PPE configuration); L: laundered particulate-blocking hood and PPE (PPE configuration); LOD: limit of detection; MLE: maximum likelihood estimation; NFPA: National fire protection association; PAH: polycyclic aromatic hydrocarbon; PPE: personal protective equipment; SCBA: self-contained breathing apparatus; THL: total heat loss; TPP: thermal protective performance.

Ergonomic mastectomy bra design: Effect on core body temperature and thermal comfort performance

The accumulation of sweat and heat between the skin and the prosthesis is one of the common causes of discomfort experienced by post-mastectomy women who wore silicone-type external breast prostheses. This study aimed 1) to investigate the effect of a newly designed heat-reduction mastectomy bra on the thermal responses and thermal comfort performance; and 2) to propose an evaluation protocol for post-mastectomy products. The heat-reduction bra and the conventional bra were made of the same textile materials but the cup of the bra under discussion had a polyurethane cup with a perforated structure along the breast root/inframammary fold. The inframammary fold is often aggravated by heat, sweat, maceration, chafe, and lack of air circulation. Nine healthy male participants were recruited to participate in the study since the women who had undergone double-mastectomy were sensitive about their scars. An ingestible telemetric pill sensor was used to collect the data of core body temperature. Participants performed a 70-min five-phase exercise protocol wearing the heat-reduction bra and the conventional bra together with a silicone prosthesis with ventilation holes on the bottom. Physiological responses (i.e., core body temperature, skin temperature, temperature between bra and prosthesis, skin humidity and humidity between bra and prosthesis) and subjective sensation responses were measured. The results were statistically significant and the conventional mastectomy bra showed a higher core body temperature than that of the heat-reduction mastectomy bra (37.3 ± 0.3 °C to 38.2 ± 0.5 °C vs. 37.2 ± 0.3 °C to 38.0 ± 0.3 °C) starting from the middle of the sitting phase to the running phase and post-exercise resting (F = 164.2, p < 0.001). Both factors, the bra and the phase, have significant effects on the core body temperature (F = 14.5, p < 0.001). The heat-reduction mastectomy bra demonstrated optimum thermal comfort performance in both the temperature and humidity than the conventional mastectomy bra.

Monitoring core temperature of firefighters to validate a wearable non-invasive core thermometer in different types of protective clothing: Concurrent in-vivo validation

This study aims (1) to test the validity of a new non-invasive core thermometer, Cosinuss°, in rest and (2) during firefighting simulation tasks, against invasive temperature pill and inner-ear temperature and (3) to compare the change in core temperature of firefighters when working in two types of protective clothing (traditional turnout gear versus new concept). 11 active firefighters performed twice a selection of tasks during their periodic preventive medical examination and a fire-extinguishing task. Without correction no correlation between the Cosinuss° and thermometer pill (ICC≤0.09, p ≥ 0.154, LoA≥1.37) and a moderate correlation between Cosinuss° and inner-ear infrared (ICC = 0.40, p = 0.044, LoA±1.20) was observed. With individual correction both correlations were excellent (ICC≥0.84, p = 0.000, LoA≤0.30). However, during and after working all correlations were poor and non-significant (ICC≤0.38, p ≥ 0.091, LoA≥1.71). During firefighting tasks, the Cosinuss° is invalid for measuring the core temperature. No differences in heat development in the two types of protective clothing was proven.

Effect of structural turnout suit fit on female versus male firefighter range of motion

The purpose of this study was to assess the impact of fit on female versus male firefighter range of motion (ROM) when donning a structural turnout ensemble. Three test ensembles were evaluated: base layers (BL), turnout suit (TS), and turnout ensemble (TE). Sixteen career firefighters (10 males; 6 females) completed a user needs survey on fit and mobility restrictions, were measured in a three-dimensional body scanner, performed a static ROM protocol, and recorded ease of movement and comfort perceptions for each ensemble. Average body measurements and absolute ROM values were calculated for each test ensemble and analyzed by gender. Results demonstrated multiple significant differences in body measurements between male and female firefighters when wearing the BL and TS test ensembles. Mobility was significantly reduced when donning the TS and TE, regardless of gender. Significant differences in trunk and shoulder flexion when wearing turnout suits were identified according to participant gender.

Cross-cultural comparison of firefighters' perception of mobility and occupational injury risks associated with personal protective equipment

Purpose. The objective of this study was to compare the effects of personal protective equipment (PPE) on firefighters' perceptions of mobility and their experienced occupational injury risks between China and the USA. Materials and methods. An online survey was conducted and a total of 328 firefighters, including 203 Chinese firefighters and 125 US firefighters, participated in the survey. Results. Both Chinese and US firefighters ranked mobility restriction as the most dissatisfactory characteristic of the current PPE. US firefighters reported the upper body as the most restricted region and self-contained breathing apparatus (SCBA) as the most dissatisfactory item. Chinese firefighters ranked boots as the leading cause of dissatisfaction, but they did not indicate any particular discomfort region. Moreover, musculoskeletal disorders (MSDs) were the most prevalent occupational injury reported by both Chinese and US firefighters. Restricted mobility while wearing PPE was closely related to the risk of MSDs. Conclusions. The findings suggested that PPE design for US firefighters should consider a balance in the weight distribution of SCBA and the overall interface of turnout gear and equipment. For Chinese firefighters' PPE, flexibility of materials for boots should be emphasized to increase mobility and reduce the risks of MSDs.