Four universities and one national research institute collaborated for this study. Based on one-to-one interviews with Korean subject-matter experts in personal (thermal) protective clothing (PPC) and PPE, and firefighters, as well as extensive literature searches, a total of 13 features (smart elements) were identified for possible use within the next generation of protective equipment. These elements and attributes are identified in Fig. 1Fig. 1.

Thirteen possible elements and attributes considered for the next generation of smart, personal protective equipment.

This Figure was used in combination with the firefighter questionnaire (Table 1).

Printed surveys were distributed in Japan and Korea, while online surveys were used in Australia and the U.S. In Korea, the written questionnaires were distributed at two fire stations in Seoul (November, 2013), and collected one month later (December, 2013). The total firefighter count at these stations was 563 and the total number of firefighters was 6,676 at 23 fire stations in Seoul. In Japan, written questionnaires were distributed at fire stations in Fukuoka City (December, 2013), and these were also collected after one month (January, 2014). At those fire stations, there were 799 firefighters. For the online surveys in Australia, an electronic invitation letter, calling for voluntary participation in the survey, was distributed centrally through the electronic mail facility to every full-time (3,457) and on-call firefighter (3,368) of Fire & Rescue New South Wales. This sample included 338 fire stations. Within the U.S., the online survey was advertised through the International Association of Fire Fighters (IAFF), and the total firefighter population covered by that organisation was appoximately 78,000. The online data collection periods were open from January to March (2014) in Australia, and from October to December (2013) in the U.S. Overall ethical approval was obtained via the Institutional Review Board of Seoul National University (Korea; SNU IRB No.E1312/001-018) and Cornell University (USA). In addition, each local fire and rescue organisation approved administration of the survey.

Data were obtained in three formats: categorical data (questions 1, 2, 7, 10, 11 and 12), quantitative data (questions 6, 8 and 9) and descriptive data (questions 3, 4 and 5). Categorical data were analysed using χ² and Kruskal-Wallis tests, while quantitative data were analysed using one-way ANOVA and Tukey’s post hoc test. Data are presented as means and standard deviations (SD) to illustrate distribution differences across these population samples. In all analyses, statistical significance was accepted when a probability value was less than 0.05. Descriptive data were grouped into related themes.

A total of 1,694 survey responses were collected from the four countries (Table 2Table 2.

	Australia	Japan	Korea	United States
Sample size1 (male:female)	167 (157:6)	351 (351:0)	413 (384:23)	763 (719:32)
Age (yr)	45.0 ± 10.4	42.9 ± 11.7	41.7 ± 9.1	42.7 ± 9.5
20–30 yr (%)2	7.5	18.6	8.9	8.0
30–40 yr (%)	21.7	23.5	32.8	31.1
40–50 yr (%)	34.2	20.1	34.2	35.7
50–60 yr (%)	30.4	32.3	23.3	21.5
>60 yr (%)	6.2	5.5	0.7	3.7
Height (cm)	178.6 ± 7.3	172.0 ± 9.8	173.2 ± 5.3	180.5 ± 8.9
Body mass (kg)	86.8 ± 11.6	71.5 ± 8.1	71.6 ± 8.6	92.6 ± 16.5
Experience (yr)	16.9 ± 9.4	20.6 ± 12.1	14.5 ± 9.2	16.0 ± 9.2

¹Sample sizes are totals with separate male:female counts shown in parenthesis. Data are means with standard deviations (± SD). ²Numbers within each of the age divisions represent percentages of the total sample.

When asked to identify the single most important element or characteristic of the next generation of PPC or PPE, the responses were clustered around three elements (Fig. 2Fig. 2.

Voting distributions for the single most important elements of the next generation of smart, personal protective equipment (see Fig. 1), as reported by Australian (AU), Japanese (JP), Korean (KR) and United States (US) firefighters. Data are national response percentages. The far right bar displays the distributions for the entire firefighter sample (Total).

Some protective elements must always be used, for example, self-contained breathing apparatus (SCBA), protective boots and helmets. However, it was of interest to evaluate international variations and attitudes regarding this equipment. In these instances, attention was directed towards air-supply durations and footwear construction.

The capacity of self-contained breathing apparatus varied considerably from country to country (p<0.05). Approximately 70% of the Australian respondents perceived the capacity of their apparatus to be about 30 min (Fig. 4Fig. 4.

Operational capacities of self-contained breathing apparatus reported by Australian (AU), Japanese (JP), Korean (KR) and United States (US) firefighters. Data are presented as national response percentages within capacity bands.

Comments and suggestions concerning improvements to the PPC and PPE currently worn (Question 5) are summarised in Tables 3Table 3.

Category	Specific recommendations
Thermal characteristics	· Very hot as soon as I put it on, and before getting to the fire scene, due to the low breathability, accumulated sweat and heat, especially in summer. The turnout gear may withstand the heat, but the body will not endure the gear. Long duration work is impossible because of the heat, and mental performance is harmed as well.· Very hot due to the moisture barrier among three layers of the PPC. The liner should be removable in summer for easier rehabilitation. Further, the moisture barrier leads to increased heat injuries including skin burns due to steam, when we are wet (US). New PPC gives greater heat stress (KR, AU, US). · Officers have to wear an ID vest over the turnout gear, which makes the heat problem worse (AU).· It would be beneficial to develop undershirts with tubing running over the trunk that could have a quick connection to circulate cold water during rehabilitation (US). · PPC gets frozen in winter when wet by water or sweat.
Over-protection	· Because current PPC is so effective at reducing the sensation of heat, we are getting caught deep in fires that are extremely hot. We don’t know the temperatures we are getting into. Once the heat penetrates the gear it is almost too late to avoid flashover. Having gear that is too good gives a false sense of security. This causes more deaths and injuries to firefighters. A sensor could be incorporated into the PPC that warns us that we are in high temperature area (US).
Load and dimensions	· Equipment is very heavy and bulky when the gear is soaked by water (outer) and sweat (inner layer); when many tools/devices are added. Hard to move, hard to doff, and hard to raise the arms or feet when wet. · The waist area is especially bulky, often with layering of the coat over the pants, a belt for tools and the SCBA waist strap, making bending over at the waist almost impossible. Newer PPE is becoming bulkier, but any adjustments that add weight to the gear should be avoided. · Sizing of PPC does not take into account each individual’s unique body shape. A female size system is especially needed. SCBA harnesses are really not user friendly for females. Female shoulders are not as wide as males, and the chest strap is sometimes not placed in the best place. For gloves, females have smaller hands with a smaller palm.
Cleaning and management	· PPC develops nasty smells from sweat, blood or contaminants. More deodorisation is required.· Current PPC absorbs too much water which increases the total weight.· Anti-pathogen layer choices are needed.· Flame-resistance is reduced as cleaning is repeated.· Lint on the fabric surface and shrinkage increase after repeating cleaning. It is hard to clean soot from the PPC and takes many hours to clean up the gear. · Light colours are avoided in terms of the cleaning and management. · It takes a long time to dry the wet PPC. Extra liners are needed because firefighters often wear their gear half-dried.

Comments have been pooled within categories. Unless otherwise indicated using country identifiers (AU [Australia], JP [Japan], KR [Korea], US [United States]), these comments were common to all four countries. PPC: personal protective clothing (turn-out gear); PPE: personal protective equipment; SCBA: self-contained breathing apparatus

The most frequently noted adverse comments were that the thermal protective ensembles were too hot and too heavy, especially after becoming wet. A comment in common with Korean, Australian and U.S. firefighters was that their new protective equipment was much hotter and heavier than the older ensemble. This may be related to over-protection30⁾. In this regard, firefighters felt strongly that equipment and clothing manufacturers should not unnecessarily increase the thermal protective properties of their clothing. It is curious to note that, in the case of the Australian sample, a moisture barrier was incorporated into the clothing, yet thermal injuries accounted for only 1.4% of all injuries within that organisation26⁾.

With regard to specific protective items, there was an extensive range of recommended improvements (Table 4), and the following general summary statements are highlighted. There was a consensus that headwear should be improved to reduce its load and hearing impediment, while simultaneously increasing the field of vision and goodness of fit. Similarly, the mass of the breathing apparatus and its impact on flexibility and mobility were crucial issues. For the gloves, firefighters reported that poor manual dexterity, due to glove stiffness and poor fit were important problems, while they preferred leather boots to rubber in terms of mass, flexibility and fit. For instance, one U.S. firefighter commented: “I have leather at my full-time department and rubber at my volunteer department. I prefer the leather much more than the rubber”.

Personal location monitoring (positioning) was the most important element preferred by both the Korean and U.S. firefighters (Fig. 2), since firefighters in trouble often cannot accurately describe their precise location to rescuers, especially in large commercial fires, and this may increase their injury or mortality risk. The ability to quickly locate trapped, lost or injured firefighters will reduce injury impact and severity, as well as increasing survival. Rescue teams may have less than 10 min to save lost firefighters if the air supply has been exhausted, due to the presence of noxious gases and the associated risk of brain damage31⁾. Also, a fire-ground commander needs to know exactly where firefighters are located at all times, so that more efficient fire fighting can occur with minimal risk to firefighters. However, signals from some of the current positioning equipment appear to be impeded by thick steel, concrete materials or the dense walls of large commercial buildings. Therefore, more effective equipment needs to be either identified or developed for these circumstances, and manufacturers should consider integrating this equipment into the PPE, in addition to the Personal Alert Safety System.

Japanese firefighters reported an automatic auxiliary cooling system as the most important of the 13 smart elements evaluated. This does not necessarily mean those firefighters experienced a greater incidence of heat illness. Instead, it could simply reflect an elevated thermal perception due to greater heat trapping within the PPC. It could also be related to the hot and humid Japanese summers, or perhaps to the length of heat exposure during fire suppression. Overheating is perceived by many to be the most common cause of firefighter injury. Whilst this is absolutely not the case for Australia’s largest fire service (Fire & Rescue New South Wales)26⁾, this statistic varies among nations. Moreover, it is perhaps one of the least controllable variables, and it represents a significant health problem for less-fit or older firefighters. Firefighters usually do not realise they are overheated until the symptoms reach dangerous levels. Therefore, slowing the rise in deep-body temperature helps prevent heat-related illness and the resultant cardiovascular and thermal regulatory complications30⁾. In the present survey, the reasons that firefighters chose the automatic body-cooling system were to improve mental performance and increase work time. Body cooling (pre-cooling) prior to entering a fire scene will reduce cardiac strain and elevate work tolerance32⁾, but it does not reduce the time taken to reach dangerously high deep-body temperatures32, 33⁾. However, an automated body-cooling system that removes heat can achieve both outcomes34⁾, but it might also increase the risk of entering dangerously hot sites due to a reduced thermal perception. Moreover, such a system will add significantly to the overall mass of the protective ensemble, and this will elevate heat production and reduce mobility.

Wireless communication systems were ranked equally with ‘vision support’ and ‘location monitoring’ systems in all countries. This result may relate to the perception that a loss, or impairment, of communications may precipitate firefighter injury. In addition, current hand-held radio systems are often cumbersome, and can become entangled with external obstructions. As firefighters already have their hands full, then the traditional communication systems need to be simplified, perhaps through moving to integrated wireless communications. It is often reported that the radio messages are unclear35⁾ and radio signals are weak36⁾. Presumably, these radio communications also suffer from the same structural interferences that impede personal positioning devices. Therefore, both systems require enhancement.

Internal fire conditions are almost always blacked out with thick smoke also impairing search and rescue operations, even when performed in good light. Since poor vision increases the risk of disorientation, and elevates firefighter anxiety and injury risk, then improved vision will be beneficial to faster rescues and quicker patient extraction. Visual support can be provided through fog-free visors, which prevent face-mask fogging on entry, and with helmet-mounted, smoke-penetrating lighting or infrared thermal imaging systems.

Monitoring room air and hot-object temperatures can help prevent flashover injuries and deaths, because those temperatures are a key to the recognition of an imminent flashover (air temperatures >400°C). Individual monitoring systems will also give firefighters advanced warning of changing conditions at the fire scene, when the local environment becomes dangerously overheated. The ability to read air and object temperatures prior to the initial fire attack may be more important in fires within light-weight truss construction, steel bow-string construction or fires involving flame impingement within closed vessels. Moreover, air temperature monitoring would assist with decisions related to depth of entry for rescue or fire extinguishment (e.g., air temperatures >150°C are untenable). Modern turnout gear allows firefighters to get deeper into buildings than ever before, but without feeling the heat. However, these life-threatening temperatures can now exceed the melting points of some components of the protective equipment.