Heat stress is especially life-threatening for firefighters and remains the number-one cause of firefighter casualties. Thankfully, the industry is fighting back with the development of several new weapons in the battle against this dangerous condition.
Heat stress is caused by a rise in core body temperature, and can be fatal. The healthy human body maintains its internal temperature at around 37°C, but a rise of just 1°C can 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.
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 in 2017 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.”
Now that the dangers of heat stress are well-known, 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.
Historically, materials that protect against external heat and flame have been hot and heavy, preventing burns but trapping body heat and moisture. Whilst it is essential for firefighter PPE to prevent transmission of fire and heat through the garment, 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 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 last year with Vienna Airport.
Mr. Szirota from Vienna Airport comments: “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.
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.
A Layered Solution
As an extension of our popular XFlex range, Bristol has developed an innovative layered solution using a set of three garments, to offer even greater protection against heat stress. The three garments comprise 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 alone, the mid-layer coat and trousers provide the required levels of protection for technical rescue. By adding the outer jacket over the top, the ensemble immediately becomes suitable for structural firefighting. So all three garments are worn to attend a house fire or industrial petrochemical fire, whereas for a road traffic accident, the outer coat is removed. This serves to improve ergonomics and comfort, and avoids problems of overheating associated with wearing unnecessary layers of clothing.
In addition to the development of new solutions for structural and technical rescue PPE, the issue of heat stress has also brought about change in the provision of protective clothing for wildland firefighting.
In many areas of the world, particularly across Australia and Asia, wildland firefighting teams are largely made up of part-time volunteers, only called upon in the event of an emergency. As such, low cost, one-size-fits-all designs have been popular in the past, frequently featuring heavy fabrics.
However, greater understanding of the danger of heat stress has led to an increase in demand for higher performance protective fabrics, lighter weight solutions and improved ergonomics and fit in wildfire protection. Even if volunteers are unlikely to come into direct contact with fire, it is now clear that hot and heavy clothing can severely impact health and productivity.
At Bristol we’ve responded by launching a new range of wildland firefighting PPE. Based on our popular XFlex style, the range has been specifically designed to protect against fire whilst increasing comfort and ergonomics, and keeping the body cool. The outer fabric is particularly lightweight and inherently flame retardant, available in either Eco Dry Shield fabric from Hainsworth, or Karvin from Estambril International. A wide range of sizes for both male and female firefighters, help to ensure a good fit for ease of movement.
It is now clearer than ever before that to operate safely and effectively, all firefighters require garments that are lighter in weight, are well fitting, and offer a high level of protection. By working closely together, 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