PROTECTION
TO THE LAST BREATH
David Crouch describes the progress of the air- purifying respirator for CBRN protection
Present-day requirements for CBRN air purifying respiratory (APR) protection begin in earnest during World War I. The release by the Germans of chlorine gas across Flanders fields during April 1915 heralded a new era in modern warfare and necessitated a whole new branch of protective equipment.
W
hile the early respirator designs, such as the Hypo Helmet, protected the eyes and respiratory tract from the eff ect of
the volatile chemical agents such as chlorine and phosgene, they were essentially fabric hoods which relied upon their protective capability via simple soaking of cloth in an appropriate chemical such as sodium hyposulphite. This crude mask gave some protection but its eyepiece proved to be very weak and easy to break – thus rendering the protective value of the Hypo Helmet null and void.
Uncomfortable to wear and not well suited to prolonged use, early respirator designs did little for the operatives’ psychological and physiological burden. Producing high breathing resistance and limited fi elds of view, such designs caused rapid fatigue due to their claustrophobic and poor performance. While this may have been acceptable to the static-line trenches of the Great War, it would prove detrimental on the modern mobile battlefi eld.
Later Cold-War-vintage S10 Respirator.
Small Box Respirator The key to successful respiratory protection on the modern battlefi eld is to reduce the physiological burden to the wearer, giving the individual confi dence to carry on with their job, while maintaining the maximum protective capability to resist airborne contamination. Even at the very early stages of military APR protection, innovation and advances can clearly be identifi ed. For example the Small Box Respirator (SBR) contained an anti-dimming compound which was applied to the inside of the eyepieces to try and prevent them steaming up. Indeed, the SBR design was so
successful that its principles were used in all later masks designed up until 1944. To avoid changing the face piece each time the SBR fi ltering system, consisting of charcoal, soda-lime, permanganate, and brimstone impregnated with sodium sulphite, was placed in a separate canister and attached to the face piece by a hose. Indeed the SBR contains all the basic elements we would now
recognise in any modern APR: a mask made of thinly rubberised material attached to a canister of charcoal for
The 21st-Century GSR Respirator.
fi ltering airborne contaminants. The SBR arrangement still proved extremely uncomfortable aſt er a time, however – and it was also diffi cult to shout commands in.
The Cold Warrior and the S6 Although CBRN use has not been of the same magnitude as the all-out chemical warfare in north France and Belgium during 1914-1918, the need for respiratory protection has continued unabated. World War II and the Cold War radically changed the global military requirements for APR protection. Airborne toxic materials had now become gaseous – for example the chlorine gas used in World War I – or particulate, such as many biological agents developed for weapons such as bacteria, viruses and toxins. Combined with the dawn of the nuclear age, the development of highly toxic chemical (e.g. Sarin and VX) and biological agents (e.g. weaponized anthrax & smallpox) from state-sponsored weapons programmes meant the CBRN threat spectrum increased massively during the 30-year period following the end of World War II. Lethal at the microgram-milligram level, many of these new CBRN agents
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Pictures: ©Scott Health
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