Many studies have been carried out in the USA to investigate the effects of firefighting on cardiovascular parameters and cardiovascular risk factors. Picture courtesy of Glowzone Inc (USA).

Know your PPE?

Published:  22 November, 2011

There is much information on clothing for firefighters but sadly much of it is neither accurate nor even useful, says Ian Moses: the bottom line is that it’s all about protection.

I have a simple and uncomplicated approach when it comes to PPE, particularly when it involves firefighters and I do have some sympathy when people are given the task of specifying or purchasing PPE for their respective services or organisations. There is so much information available and sadly not all of it is relative, accurate or even useful.

I do not intend to quote regulations and guidelines in any great depth, nor do I intend to be product specific, that’s for another day and another article.

It’s all about protection of the wearer, allowing them to carry out whatever tasks they have as safely as possible. There are of course other things to be considered, risk assessments and the management of those involved.

The bottom line is that firefighting is dangerous, always has been, always will be, and in spite of risk assessments and dynamic risk assessments firefighters still get burned and worse.

The regulations covering PPE state that “PPE is the last line of defence” – I never bought that when they said it, and I don’t buy it now.

There are cases where without the high level of PPE issued, the firefighter cannot do what they need to do. That of course is my opinion and I am sure that there are many people that will disagree with me.

There are lots of discussions about the performances of outer shell textiles, but it should be remembered that outer shell textile, important though it is, is only one of the components used in the construction of garments. Each outer shell fabric has its limitations and it’s for you to find out what they are, how they react when exposed to heat and flame, and then you need to decide it its good enough for what you require.

Most garments now are fitted with moisture vapour barriers of various kinds, thermal barriers that are stitched to the lining fabric. Though, the uses of alternative lightweight options are available.

Each and every one of these components are important, the failure or the omission any of these components may cause a catastrophic failure in the garment. When you come to specify PPE for your firefighters each and every component needs very careful consideration.

Now “light” is good, everyone likes it, the firefighters like it, and so do I. The only way to achieve this is to use lighter products or take something out. But there is a famous saying: “You can’t solve one problem by creating another,” so any steps taken to reduce the basic weight of the garments will have implications on the performance. You need to understand that the garment is a barrier between the wearer and the hazard and that the most critical hazard is heat and flame. If everything goes wrong the escape time afforded to the wearer is critical. In fact their life might just depend on it.

There are two main standards used in the manufacture and guidance for the purchase of firefighter garments, EN 469-2005 and NFPA 1971-2007.

Most of the performance testing that is carried out in these standards is more based on reproducibility of the tests as opposed to realistic tests of what actually happens to firefighters in the event of an emergency.

In EN 469 the two major tests carried out are EN 367 Heat transfer Flame and EN ISO 6942 Heat transfer Radiation. The tests set a minimum performance to have a garment certified at Level 1 or Level 2.

The problem lies in the interpretation of these tests, what these tests actually identify. Let me explain as simply as I can.

“EN 367 Heat transfer Flame” tells us that using your assembly, at Level 2, your firefighter is badly burned at 13 seconds. EN ISO 6942 says that using your assembly, at Level 2, your firefighter is badly burned at 18  seconds. The time difference between 1st and 2nd degree burns in both tests are 4 seconds.

What I would want to know is at what point after the wearer has started to suffer 1st degree burns do they start to howl with pain as they burn. The time line between 1st and 2nd degree burns does in no way give the wearer four seconds of escape time. After 1st degree burns has been identified, they will continue to burn second by second.

The same applies to the TPP test (Thermal Protective Performance Test), where a minimum TPP of 35 identifies that your firefighter is badly burned.

What we should be concentrating on is to stop the fire fighter suffering 1st degree burns in the first place.

I am a great believer in the independent manikin test, though there is reluctance for this to be accepted as a mandatory test in EN 469 because some European partners feel that any burns to the firefighter that would be deemed as acceptable in the test results, are not acceptable in real time.

Now I can understand that. But we do that with our current testing – our current testing already identifies burns, although not percentages. The main difference is that using the manikin you can identify any weak areas in your ensemble and have a reasonable idea of the volume of injury that the wearer may sustain if they were exposed to high levels of flame. The other important thing is that once you have identified where the weak areas of your assembly is, you then have the opportunity to rectify the weak areas.

I have witnessed many tests and they are indeed reproducible with little variance from one test to another. We are fortunate that we have an excellent testing facility in the UK, totally independent and beyond reproach. Remember not all manikins are the same, the sensors may be different and the software used to calculate burns may differ.

The testing of garments to assess the effect they have on the physiological well being of the wearers has been done to death. I have a nice collection of these as well.

In fact Grampian Fire and Rescue Service (Scotland) carried out its own study 15 years ago; it was called the “Assessment of Heat stress in Fire-fighters during Flashover Training” and was carried out by the Department of Biomedical Sciences at Aberdeen University. This was done using rectal thermometers, heart rate, deep body temperature and skin temperature was recorded at three different sites on the body. We used instructors with a mean age of 39, so we selected what we felt was a fair representation of the firefighters we had in our employ. So no super humans were used. To cut a long story short, they identified the following: heart rate increased during each study, but was consistent with carrying out moderate work. There was no significant increase in the deep body temperature readings, and they were happy to say that there was little evidence of heat stress.

Another major study has just been completed by University of Illinois (Fire Fighter Safety Research Centre). Eighty-eight pages of information. Another excellent study, and what follows is what they concluded.

In Part 2 they describe an integrated research study designed to investigate the effects of firefighting on cardiovascular parameters and biomechanical variables. This study documented laboratory based cardiovascular risk factors among a large cohort of firefighters and investigated the effects of different PPE configurations on physiological and biomechanical responses to live firefirefighting activities.

Study participants included 122 male firefighters from across the state of Illinois with a wide range of firefighting experience. The group was nearly equally divided between career and volunteer firefighters. The participants were relatively young (mean age = 29.5 years), were free of known cardiovascular disease or balance/gait impairment and were not taking medications for hypertension or high cholesterol. Participants engaged in 18 minutes of firefighting activity in a burn tower that contained live fire. Temperatures were maintained at approx 100ºF and 170ºF at the floor and waist level, respectively. Firefighting activities included repeated work-rest cycles, with firefighters doing stair climbing, forcible entry, search and rescue, and a simulated hose pull. Major findings include:

•            A large percentage of the firefighters who participated were overweight or obese based on BMI measures.

•            A large percentage of these firefighters were pre-hypertensive or hypertensive.

•            Eighteen minutes of simulated firefighting activity causes significant physiological disruption including an increase of heart rate (75 bpm) and an increase of core   temperature (1.2ºF).

•            The simulated firefighting activities caused a significant increase in platelet numbers and a significant increase of platelet activation (resulting in faster clot formation).

•            Firefighting activity resulted in an increased level of coagulation (increased factor VIII activity and PF1.2) and significant changes in clot breakdown (fibrinolysis).

•            PPE configuration had no significant effect on physiological, perceptual, blood chemistry, or coagulatory responses to firefighting activity.

Most of these studies have been done because the US loses around 50 firefighters per year due to heart attacks and/or strokes. This equates to (based on 1,200,000.00 fire-fighter) 0.4166 %. A report just concluded by CDC (2008) in the United States identified that 25,500,00.00 males and females in the US suffer from some kind of heart disease, based on a population of 300,000,000.00 that equates to 8.333 %, so the statistics for firefighter is well within the national parameters. And it should also be remembered that there is no age limit place on the volunteer fire departments. I read very carefully all the LODD (Line of Duty Deaths) and it is not unusual to see firefighters in their 70s listed.

A study carried out by one of the UK’s premier manufacturers in 2004 using ten different designs and textiles assemblies, some standard and some lightweight, summarised the following; that there was no significant differences between the fire kit assemblies in the effect on physiological effects on the wearers, though there were differences in fit and comfort. 

We should bury this now

You are responsible to ensure that you get it right first time; someone’s life may depend on it. If you are unsure what you are doing, you can seek help from outside. Don’t be afraid to ask for it.

 

About the Author

Ian Moses worked for Grampian Fire and Rescue in Scotland for 31 years and has many years’ experience working with firefighting PPE. He has a passion for textiles in particular, and has spent many years researching PPE not only in the UK, but in Europe and the USA. After retiring from the fire service he decided his experience could be of assistance to others. With so much contrary information in the market place, he believes his experience can help others. His company is called Scotfire Safety Solutions and he can be contacted on: ianmoses@hotmail.com or +44 7870 557086.

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