Pre-cooling to prevent heat illness

firefighter health: pre-cooling

Pre-cooling to preventheat illness

Fire service instructors are at increased risk of ill health because of the number of fires they are exposed to, according to researchers at the University of Brighton. However, evidence suggests that pre-cooling with ice slurry could help to reduce the physiological strain caused by repeated exposures, reports Lotte Debell.

The UK's Fire Service College has implemented special ice machines that dispence ice 'cubelets' to pre-cool its instructors.

Professional sport has long understood the benefits of pre-cooling to reduce the occurrence of heat illness in athletes, but despite the fact that firefighters are exposed to far higher temperatures while enduring intense physical exertion, pre-cooling is not an established protocol in fire services. In part, this is down to the nature of emergency response – firefighters don’t know when or where they will be

called to an incident, making preparation difficult – but that is not the case for all fire service personnel.

There is a group more at risk of heat illness even than firefighters, and that is fire service instructors. Instructors can be exposed to multiple fires in a day, and without adequate preparation and recovery time and procedures, they could find themselves even more susceptible to some of the chronic and acute health conditions that tend to affect firefighters, including heat stress and cardiovascular illness.

Around six years ago in the UK, when reports of ill health among fire service instructors raised a red flag with the Health Management Research Project for Live Fire Instructors, the Environmental Extremes Laboratory at the University of Brighton carried out a small pilot study to try to understand what was going on. The small-scale research project involved six instructors and six non-fire service individuals and found evidence that repeated exposure to live fires can cause changes in immune function, a decrease in aerobic fitness, and effects on lung function. A larger-scale study was called for, and this started with a survey of the working practices of both fire service instructors and firefighters across the UK. The results of this survey have just been published.

‘We wanted to find out what fire service instructors are experiencing, and whether this is unique to instructors,’ explains PhD researcher Emily Watkins from the University of Brighton, who designed the study. 130 instructors and 232 firefighters responded to the survey, and the responses enabled the researchers to identify the differences between the two groups. These include variations in the type and frequency of new symptoms reported and highlighted the increased risk faced by instructors. ‘From the survey, we found that 41% of instructors – a huge number – were experiencing new symptoms of ill health since becoming instructors.’

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firefighter health: pre-cooling

Dr Alan Richardson, a co-author of the Brighton studies, presenting at the Fire Fit Conference.

These symptoms include (from most frequently to least frequently reported) fatigue, headaches, broken sleep, musculoskeletal pain, heavy sweating, problems thermoregulating, heart palpitations, coughing and breathing problems, blood-shot eyes, and mood swings. In contrast, the most common symptoms reported by firefighters – 21% reported new symptoms since starting their role as opposed to 41% of instructors – include back pain, PTSD or depression, coughing or breathing problems, and headaches.

The survey found an association between the number of times an instructor wears breathing apparatus in a month – divided by type of exposure into BA, BA cold/no smoke, and compartment fire behaviour training – and their likelihood of experiencing new symptoms of ill health. More specifically, the results suggest that instructors who wear breathing apparatus more than 11 times per month are 4.5 times as likely to experience symptoms of ill health compared with those who complete five or fewer wears.

It also found that work practices vary widely across the UK with a lack of consistent guidance on number of wears,

preparation and recovery periods, pre- and post-cooling practices, and hydration advice. Almost 40% of instructors who responded to the survey felt that they completed too many wears per week and 45% did not know whether they were subject to a wear limit set by management. Those who did have a wear limit (55%) reported that it ranged from two to ten times per week.

The study also found a wide discrepancy in preparation and recovery procedures. Almost three-quarters of respondents said they were not allocated a specific period to prepare for a wear and 70% had no set recovery time. Just over 40% also reported no hydration guidelines prior to a fire exposure. Tellingly, the majority of instructors (65%) reported that they still felt worn out and warm after their recovery period.

Impact of repeated exposure It is well-known that exposure to intense heat and exertion in PPE can lead to heat illness, such as heat exhaustion and heat stroke, the consequences of which can be deadly, particularly in an emergency situation where impaired responses can

3M donates equipment to moorland firefighters

UK fire crews tackling moorland blazes have received a donation of PPE from 3M. The technology company donated 150 reusable respirators and 200 FR bump caps to Lancashire Fire and Rescue Service and Greater Manchester Fire and Rescue Service to assist with the response efforts. Around 200 firefighters have been involved in efforts to control two wildfires in Lancashire and a further two in Greater Manchester following a prolonged heatwave across the UK.

3M provided crews with its 7500 series reusable half-masks with particulate filters and its flame-retardant HC23 bump caps, which also offer UV protection.

Neil Taylor, service training manager at LFRS, said: ‘Since the moorland fires broke out we have been overwhelmed by the generosity shown by businesses and public, who have gone above and beyond to donate items to us in order for us to focus our efforts solely on tackling the fire. The donation of masks from 3M has provided us with a reserve of resources should they be required by the many crews working on the moors, and the additional feature of sun protection will be a further benefit for our crews. We would like to thank 3M for their generosity.’

A spokesperson for Greater Manchester FRS, where crews have been battling a moorland fire that covered seven square miles at its peak, added: ‘We have been

overwhelmed by all the donations we have received over the past three weeks as our firefighters have fought to tackle two major moorland fires in extremely challenging conditions. These have been unprecedented circumstances for GMFRS and we are really grateful for all the support.’

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endanger both firefighters and victims. This was highlighted by research published last year by the University of Edinburgh (F&R Q2, 2017), which conducted research into the reason behind the high proportion of heart attacks among on-duty firefighters. It found that dehydration and a rise in core temperature caused firefighters blood to become thicker and more likely to clot after exposure to a fire. The team also found evidence of an inflammatory response within the body that increases the risk of a cardiovascular event.

Investigating the body’s inflammatory response to heat exposure was a key aspect of the Brighton study. As the authors explain, ‘numerous inflammatory markers, such as Interleukin-6 (IL-6), platelet number, and C-reactive protein have been documented to increase following fire exposure. Repeated wears may, therefore, have a chronic effect on these markers, increasing an instructor’s risk of a cardiac event.’

Previous research has found that repeated fire exposures can lead to increased levels of Interleukin-6 at rest of up to 17.0pg mL. Median resting values in healthy men are 1.46pg mL (Ridker et al 2000). This is significant because increased IL-6 can lead to the development of atherosclerosis (the narrowing of the arteries due to plaque build-up). As the Brighton study states: ‘Inflammation plays a role in both the initiation and progression of atherosclerosis. Elevated levels of inflammation, exacerbated by reduced recovery time between wears, suggests that fire service instructors may be at an increased risk of a cardiovascular event as the frequency of heat exposures rises.’

‘What we found supports the conclusions of the Edinburgh study,’ says Watkins. ‘The difference is that we are looking more at chronic impacts, as this is where research is lacking. Another study we are working on is looking specifically at the chronic impact of repeated fire exposure on instructors. We have taken blood samples from firefighters and instructors in rest conditions and looked at predictors of cardiac risks compared with the number of exposures. We found that instructors have increased risk markers on a daily basis, and those with a higher number of exposures are at greater risk.’

The results of the survey underlined the findings of the initial pilot study and the need to reduce the occupational health impacts on instructors. ‘The need for education and guidance on hydration and pre- and post-cooling is one of the main things that came out of this survey,’ says Watkins. ‘There is a wealth of research about hydration and post-cooling, but there isn’t much in the way of clear advice about pre-cooling, so that’s where we decided to focus.’

BRIStol UnIFoRMS' top-to-toE SolUtIon

PPE supplier Bristol Uniforms will be using its biggest-ever stand at this year’s Emergency Services Show to showcase its top-to-toe PPE solution designed for the Central PPE and Clothing Contract collaborative framework.

Alongside its existing extensive range of PPE solutions for the emergency services, Bristol’s collection for the CPCC includes the Xflex structural ensembles, layered jackets, rescue jackets and USAR ensembles. A dedicated section of the stand will feature all the structural firefighting and rescue garments and accessories available to members of the contract.

Also on display on stand A70 will be other PPE solutions such as Air Ambulance and HART apparel and public order crowd control PPE. The company will also be showcasing its particulate protection firefighting hood, developed using Nomex Nanoflex to filter out harmful smoke particles, and Bell Apparel’s high-vis and wet weather clothing range.

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firefighter health: pre-cooling

Pre-cooling Pre-cooling, as Watkins explains, aims to reduce the risk of heat injury occurring, whereas post-cooling is about reducing the impact of heat illness. If effectively employed, pre-cooling can reduce the body’s core temperature and increase its ‘heat sink’, with obvious benefits for firefighters who are at risk of heat stress from a rise in their core temperature. Up until now, however, pre-cooling research and application has been focused on professional sports rather than occupations, and to be effectively used by fire instructors, let alone firefighters, pre-cooling methods need to be quick and easy.

That’s why, when designing the study, the Brighton team investigated methods of pre-cooling already in use by fire services. These include forearm cooling and the use of phase-change vests, as well as consumption of ice slurry, which has been highlighted by previous research as a possible effective and practical pre-cooling method for the fire service. In addition to a reduction in core temperature, the team were also hoping to see a decrease in the body’s inflammatory response.

The study was designed to put the three pre-cooling methods to the test alongside a controlled exposure. A 15-minute pre-cooling period – the length of time was determined based on instructor responses about their

London Fire Brigade uniforms to be tracked with RFID

RFID tags from Vero Solutions will be used to track the uniforms of London Fire Brigade’s 4,800 firefighters.

Bristol Uniforms, which supplies the uniforms, already uses Vero RFID tags to track the uniforms of Cambridgeshire Fire and Rescue Service. The tags are sewn securely into a pocket of each garment and are designed to withstand temperatures of up to 150°C.

Each garment is scanned using a handheld RFID reader at key points of the managed service process, from point of collection to washing, inspection, repair, and return delivery.

‘The use of RFID readers has reduced the time our drivers take when collecting garments,’ said Edward Shepherd, service operations director at Bristol Uniforms. ‘A bag of items can now be scanned simultaneously without having to take a single garment out of the bag.’

London Fire Brigade is one of the largest firefighting and rescue organisations in the world. Each firefighter will be provided with twelve items of uniform for both structural firefighting and urban search and rescue operations, each fitted with an RFID tag, totalling more than 60,000 pieces of kit.

The system is due to go live in October. Bristol Uniforms will also supply more than 5,000 uniform items to Buckinghamshire Fire and Rescue Service, which will also be tracked with RFID tags from Vero Solutions.

average preparation time – was followed by a 45-minute simulated fire exposure in which participants were dressed in full PPE with a backpack to replicate the weight of breathing apparatus. Researchers tested a number of physiological responses including core temperature, heart rate, physiological strain index, skin temperature, perceptual strain, gas analysis, and IL-6.

Forearm cooling, which involved participants submerging their arms up to their elbows in cold tap water for the pre-cooling period, did not result in a reduction in core temperature, but it did make some people feel cooler. But, says Watkins, that is not necessarily a good thing in a fire exposure. ‘A reduction in perceptual strain might result in someone working harder, which could potentially raise their core temperature higher than it might otherwise go.’

Phase-change vests were also found not to be effective at reducing core temperature prior to or during exposure. These vests – the type used was one already in use by fire services for cooling purposes – are made from a material that absorbs heat and turns to liquid at a certain temperature, in this case at a skin temperature of 27.78°C. ‘In the study we asked instructors to put the vests on for the 15-minutes prior to exposure and to keep the vests on during the exposure. However, we found that the extra weight of the vests likely counteracted their cooling benefits.’

The final method tested was ice slurry consumption, and this was found to reduce core temperature by an average of 0.24°C prior to exposure. It was also effective at keeping that core temperature lower during the exposure itself, reducing the core temperature of participants for around 20-25 minutes. ‘By the time the core temperature started to rise, it was therefore lower than it would have been without pre-cooling with ice slurry.’

Impact on inflammation Ice slurry might have a beneficial effect on core temperature, but it didn’t have any impact on the inflammation markers tested as part of the study, such as IL-6. 'However,' says Watkins, 'the study did not test all markers of inflammation and there are many other predictors of cardiovascular events that were not considered in the study.

‘The main thing we looked at was the impact on overall thermal exposure, and how high the core temperature gets throughout the day is linked to those inflammation markers. So, as instructors have multiple exposures, a lower overall thermal exposure throughout the day could reduce inflammatory markers at the end of the day.’

In short, as the study states, ‘it cannot conclusively be claimed that pre-cooling has no effect on the risk of cardiovascular events’. But clearly, more research into the short- and long-term reduction of inflammation is called for.

Practical application Ice slurry is effective because it increases the body’s heat storage capacity as a result of the additional energy required to melt the ice. Its core temperature cooling effect aligns with previous studies into the efficacy of ice slurry, but the Brighton study recorded a lessened impact as it was designed around an easily-applicable method of consumption.

Previous studies recommended measuring out ice slurry at 7-7.5g per kg of an individual’s body weight, which would involve firefighters weighing themselves regularly and weighing their ice every time they made up the ice slurry. Instead, Watkin’s team opted for a more practical 500ml of ice slurry – a standard water bottle-sized quantity – consumed 15 minutes prior to exposure to align with the average instructor

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firefighter health: pre-cooling

Heathcoat Pure System fabrics on show at ESS

Heathcoat’s new Pure System with PBI will be the main theme of the fabric manufacturer’s stand at this year’s Emergency Services Show in the UK in September.

Also on display will be the company’s PBI TGP fabric. This has been created to provide high-strength yet lightweight protection for technical rescue or

wildland operations.

The Pure System offers a range of fabrics that combine the heat and flame protection of PBI with the strength and durability of Kevlar. The system combines the fibres at their most effective blend to provide excellent performance and maximise safety.

To develop Pure System fabrics, Heathcoat re-engineered the optimal PBI blend to eliminate unprotected exposed aramid fibres, which can compromise garments if they come into contact with flame and increase the potential for the fabric to break open. Instead, Heathcoat blended PBI fibre with Kevlar for added strength, creating uncompromised outer shell fabrics optimised for comfort with better strength retention after UV exposure.

'Heathcoat has a history of manufacturing PBI fabrics that have seen garments exceed 10 years of continuous active service,’ said Mark Drysdale, commercial manager of protectivewear at Heathcoat. ‘This range is a significant development advance in our high-performing range. All the fabrics developed are designed for improved breathability and comfort and an increased percentage of strength retention after exposure to UV.’

The company has also announced a new development in the replacement of C8 with C6 in its protective fabric coatings to meet changing environmental regulations. Heathcoat’s Petrogard+ using the company’s C6 technology is now used on all its protective outer fabrics, including the PBI Pure range. It is a safer, greener solution that provides durable chemical repellency combined with a UV inhibitor to retain strength.

pre-exposure preparation period.

The UK Fire Service College has already taken this recommendation on board and has installed a machine that produces ‘cubelets’, condensed ice cubes that can be eaten by instructors prior to exposure. East Sussex Fire and Rescue Training Centre has also implemented this pre-cooling method on the back of Brighton’s recommendations.

Firefighters are also at risk of heat illness and therefore would also benefit from reducing their core temperature prior to a live fire exposure, but how practical is this in an emergency situation? ‘This is something we have been asked a lot,’ says Watkins. ‘Obviously, our trial was looking at instructors and pre-cooling is logistically more difficult for firefighters from an operational perspective, but we believe the method we have recommended is not incompatible with emergency response.’

Watkins suggests that firefighters could fill a bottle with ice slurry and keep it in a cooling bottle in the fridge. ‘They can then grab this with their kit when they are called to an incident. As they are travelling to the incident, setting up on arrival, and talking to people they can be sipping the drink. They may not be able to drink the whole bottle, but even a small amount is a lot better than doing nothing. It is potentially feasible, we just need to work on getting ice slurry machines into stations and getting firefighters to adopt this behaviour.’

Learning resource It is with the aim of arming instructors and firefighters with the information to inform behaviour changes that can help to protect their health that the Brighton research team has been commissioned by the UK’s Fire Brigades Union to produce a learning resource pack for fire training centres and firefighters in training.

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firefighter health: pre-cooling

PGI Announces the Introduction of FireLine Multi Mission Dual Certified Garments

The leading cause of line-of-duty deaths among firefighters is sudden cardiac arrest, attributed to heat stress, overexertion, and pre-existing medical conditions. The weight of a firefighter's PPE can be a contributing factor in conditions such as heat stress, but even though the vast majority of calls a fire service receives do not involve a fire – they are non-emergency, rescue, good intent or false alarms – the responding firefighters must still be kitted out in full PPE. To help combat this issue, PGI has developed a new range of garments for firefighters.

PGI says its Fire Line Multi Mission dual-certified garments are lighter, more flexible, and more ergonomically designed than traditional turnout gear, and have been developed to reduce heat stress and firefighter fatigue. They are designed to maximise protection, comfort, and mobility using proven FR fabrics that combine flash fire, thermal protection, and abrasion resistance in a single-layer garment.

Fire Line Multi Mission technical rescue gear features articulated elbows and knees, generous gusseting, radial sleeves, and anatomical patterning for improved freedom of movement. There are also a number of customisable options.

UL-classified, Fire Line Multi Mission PPE meets or exceeds both the NFPA 1951 Standard on Utility Technical Rescue for Protective Apparel and the NFPA 1977 Standard on Protective Clothing and Equipment for Wildland Firefighting. The company also claims that its garments are only about a third of the cost of traditional turnout gear.

PGI president Jim Sonntag said: ‘We are committed to leading the way in the design and manufacture of high-performance PPE. We pride ourselves on employing the most advanced materials and premium accessories, allowing us to create technical products that can be trusted to perform in the most extreme conditions. Our philosophy is to design and manufacture products that are as good as they can possibly be, performing over time and beyond expectation at the point of extreme need.’

‘Ultimately, the aim is to provide guidance to fire services on the safe maximum number of heat exposures in one month for instructors. The average number of exposures per month is currently 13 but there are no regulations in the UK that govern this, so we want to find out whether this is realistic and what impact it is having. We want to create general guidance that fire services can use to set their own procedures.’

To this end, these studies form part of a larger body of work being carried out by Brighton’s team of researchers into firefighter health, and specifically fire instructors. ‘We are also working on a longer-term monitoring project working with fire instructors and firefighters. This is looking at core temperature changes and contamination risk, and we will examine blood

samples to try to understand whether the type of exposure changes the risk factors. This study will also look at decontamination procedures and will hopefully start to answer some of the current questions around firefighters’ exposure to chemical contaminants.’

Another project will focus specifically on female firefighters as women respond to heat differently to men. ‘We will also look at female-specific cancer risks. Although with each service there may not be many female firefighters, if you take the worldwide firefighting community there is a significant number of women and they need to be considered.’

The Brighton team has just carried out a female-specific international survey of firefighters to establish areas of concern. ‘From the results, we can see that women in the fire service are concerned about heat exposure, menstrual cycles and menopause, female-specific cancers and fertility impacts.’

In addition to the collaboration with the FBU, Watkins and her colleagues have been working with the Compartment Fire Behaviour Training Instructors User Group, feeding back the studies’ findings, which the user group, in turn, feeds back to the fire services. ‘Everyone is keen to find out what they need to do to stay safe,’ says Watkins. ‘There is a real culture change taking place – I see far fewer dirty kits now than when I first started on this project six years ago. Hopefully, the educational tools we create for training centres will start to see this guidance and advice provided as standard to all new firefighters as they go through their training.’

Heat stress and cancer risk – a conflict?

Heart attacks and cancer are the two leading causes of deaths among firefighters. As the drive to minimise the health risks of the job gathers pace, more and more research is being carried out into both areas in an attempt to provide guidance and procedures that can help keep firefighters safe. But what happens if there is a playoff between the two?

Pre-cooling is one aspect of preventing heat illness. As the research from the University of Edinburgh highlighted last year, it is also important that firefighters take steps to rehydrate and bring their core temperature down as quickly as possible after coming out of a fire to minimise their risk of cardiovascular events. However, where the reduction of risk from intense heat and exertion requires firefighters to cool down as quickly as possible, by, for example, removing or opening PPE, minimising the risk from potentially carcinogenic contaminants requires firefighters to avoid removing PPE and breathing apparatus until they have completed overhaul.

One way of addressing the problem could be through the effective use on-site decontamination when firefighters come out of a fire – the University of Brighton has just had a grant approved to explore decon procedures in the UK – which is already in use at some fire services. On-site decon could allow firefighters to quickly minimise the contaminants risk, allowing them to then find a safe area, preferably in the shade, to remove their PPE, rehydrate with cool water or preferably ice slurry, and take other measures to cool down as quickly as possible.

Ultimately, however, the answer is to take a holistic approach to safeguarding firefighter heath. It’s no good developing protocols for each risk in isolation. The quickest way to ensure that advice is ignored is to make it contradictory and confusing. Instead, each fire service should focus on developing best practice that addresses the main risks their personnel face as a result of their operational profile and educate and inform staff about how best to protect themselves.

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