Heat Stress is a potentially fatal condition caused by a dangerous rise in core body temperature. The healthy human body maintains its internal temperature at around 37°C, but a rise of just 1°C to 38°C is enough to cause significant harm and disorientation. Heat stress increases muscular fatigue and interferes with cognitive function, causing a serious loss of balance and co-ordination. It also increases cardiovascular strain, which can lead to cardiac arrest and death.
Over recent years, studies have shown that heat stress is especially life-threatening for firefighters and is the number-one cause of casualties. Research from studies such as Firefighter Fatalities and Injuries: The Role of Heat Stress and PPE (University of Illinois USA, 2008) have shown that more firefighters die in the line of duty from cardiac arrest than from any other cause. And in addition to the elevated risk of cardiac arrest, slips and falls brought on by loss of co-ordination can prove just as fatal in a firefighter’s hostile working environment.
Independent research published earlier this year by the University of Edinburgh and funded by the British Heart Foundation, Fire Simulation and Cardiovascular Heath in Firefighters, looked at the relationship between cardiovascular attacks suffered by firefighters and operational activity. It found that: “Exposure to extreme heat and physical exertion during simulated fire suppression increases thrombogenicity, impairs vascular function, and causes myocardial injury in healthy firefighters.”
The dangers of heat stress are now well-known in the industry and firefighters across the world have adopted a range of preventative measures when attending operations. Hydration is particularly important, and firefighters on the front line are routinely provided with bottled drinking water. Time spent in the heat of a fire is now closely monitored and restricted, with crews rotating roles and sharing heavy physical work.
At the same time, PPE manufacturers, designers and their suppliers, understand they have a vital role to play in developing protective clothing that keeps the body as cool as possible. For us, the fight against heat stress is ongoing. Whilst we have worked together in recent years to make significant strides in devising successful solutions to safeguard against heat stress, it continues to be a key focus in the development of new products and technologies.
Fabric Technology Solutions
Historically, materials that protect against external heat and flame have been hot and heavy, preventing burns but trapping body heat and moisture. It is of course essential for firefighter PPE to prevent transmission of fire and heat through the garment, but it is also crucial to allow internal heat and moisture to escape, to keep the body cool and dry.
Over the years, innovations from leading fibre and fabric manufacturers, such as WL Gore, Hainsworth, PBI Performance Products and DuPont, have helped PPE manufacturers to produce multi-layered garments that protect from inside and out. A select combination of fabrics can offer resistance to fire, increased breathability, control of moisture, and a lighter weight – all of which help to reduce the occurrence of heat stress.
DuPont and PBI, for example, provide highly specialised and lightweight fibres for the outer-shell of a garment, which crucially provide outstanding air permeability and breathability, allowing metabolic heat to escape. But when these fabrics come into contact with intense heat, such as from a flash fire, they instantly thicken, creating a barrier helping to prevent burns.
Modern firefighting garments combine this type of outer shell with an inner moisture barrier and liner system which draws sweat and moisture away from the skin, helping to keep the body cool and dry.
One of the latest weapons in the battle against heat stress has been the development of the Goretex Moisture barrier with new Gore Parallon System.
This new fabric is particularly light-weight and offers unprecedented levels of breathability and thermal protection, particularly when wet, helping to prevent dangerous increases in core body temperature.
Incorporating the most advanced moisture management technology available, this sophisticated solution faired extremely well in recent trials, outperforming other leading moisture barriers on the market. Testing showed that it lost only 4% of its thermal protection when wet and displayed the lowest resistance to the evaporation of sweat.
At Bristol, we are now offering customers this ground-breaking new technology as part of our XFlex range, securing our first order earlier this year with Vienna Airport.
Mr. Szirota from Vienna Airport commented: “We travelled to the BTTG™ testing centre in Manchester to see for ourselves this fabric combination being put through its paces and the results were impressive.”
New developments in combatting heat stress are not just confined to structural PPE. Search and Rescue operations often take place once the immediate danger of flame is removed, with USAR or technical rescue teams entering enclosed and confined spaces, where high temperatures are a hazard.
Bristol’s RescueFlex offers a high level of flexibility to afford manoeuvrability in confined spaces, and is lightweight to minimize heat stress. It is also now available in new Gore® Varde fabrics, specifically developed to offer significantly more comfort and flexibility in rescue operations. Using the very latest fabrics from WL Gore, the new Gore® Varde garments provide a high level of protection against wind, water and flame in just one light, breathable layer. Crucially, this allows firefighters to work in confined spaces or in adverse conditions for longer and in more comfort.
The durable waterproof and windproof qualities of the fabric, including low water pick-up and quick re-dry properties, ensure protection from the elements on the outside. At the same time, sweat is able to pass through the fabric from the inside, keeping the wearer dry and reducing the risk of heat stress. The fabric is also self-extinguishing and flame retardant, protecting firefighters from the possible hazard of unexpected fire during a rescue operation, and enabling crucial escape time.
Along with fabric technology, the design and style of a garment can play a crucial role in contributing to a firefighters’ safety and minimising heat stress. The work of a firefighter is often very physical, involving running, climbing, crawling and lifting heavy equipment to carry out the job in hand in a hot and hostile environment. Protective clothing that is ergonomic and easy to move in will make the role less strenuous, and reduce the build up of body heat and sweat.
At Bristol, we design garments that work with the firefighter rather than against them. Both National Civil Defence Forces and oil and gas companies across the Gulf region tend to favour our innovative XFlex range. This structural firefighting kit is lightweight, breathable and ergonomic, with distinctive sports styling and suitable for a range of operations. Qatar and UAE Civil Defence Forces have both opted for the XFlex range, but its flexibility means it is just as suitable for industrial firefighters, such as our customers the Abu Dhabi Company (ADCO).
As an extenstion of our popular XFlex range, Bristol has developed an innovative layered solution, to offer even greater protection against heat stress. In a move away from the traditional approach to PPE design, Bristol was the first to devise a layered concept, LayerFlex, using a set of three garments. These consist of standard structural XFlex trousers, a specially adapted XFlex outer jacket, and RescueFlex jacket which is worn underneath.
LayerFlex is particularly useful when a fire service is faced with a range of operations requiring varying levels of protection. When used in different combinations, the mid-layer coat, top coat and trousers provide the required levels of protection for structural firefighting as well as technical rescue. The options they provide ensure that a firefighter is able to wear garments to suit the role they are undertaking, rather than wearing the same structural fire clothing for all roles. For example, all three garments would be worn to attend a house fire or industrial petrochemical fire, whereas for a road traffic accident the mid-layer coat and trouser combination would be more suitable, with the top coat removed. This serves to improve ergonomics and comfort, and avoids problems of overheating associated with wearing unnecessary layers of clothing.
By working closely together in this way, fabric and fibre manufacturers and PPE designers are constantly striving to adapt and improve protective garments to keep firefighters safe from the inside out. Whilst the full physiological effects and implications become clearer with ongoing research, firefighters can be assured that the PPE industry is continually building on its armoury to win the fight against heat stress.
For more information, go to www.bristoluniforms.com