History and invention of the gas mask: the technical evolution from its origins to the present day

There antigas mask It is a safety breathing device mainly used in wartime for protect the respiratory tract from inhalation of air pollutants and toxic gases. The first modern gas mask, theHaslett Inhalerwas patented in 1849 from Lewis Haslett: drew inspiration from breathing masks, which were used as respirators and were used solely for industrial purposes. The Haslett Inhaler would later become the model on which the gas masks used in the First World War and Second World War were developed, up to the ones we still use today.

Who invented the first modern gas mask, the Haslett Inhaler

Lewis Haslett's mask was a mobile breathing apparatus for purifying air. The device, patented on June 12, 1849, had a mouthpiece with two valves (one for inhaling through moistened wool and one for exhaling) and allowed the person wearing it to walk freely.

Haslett mask design

It was a device that was already revolutionary in a certain sense, because before its invention there was theanti-smoke helmet (which was later transformed into the first diving helmet) patented by the English brothers John and Charles Deane, but it had a problem: the tube. The Deane brothers' copper helmet (an invention later taken up by the British engineer Augustus Siebe who created the first standardized anti-smoke helmets) had a leather tube on the back which was supposed to supply the air pumped using a double bellows, but which allowed a reduced mobility. Having a limited length, one could not move too far from the air source, and this detail made Haslett think of building a mobile breathing device.

In the following years, various inventors replicated and improved the Haslett Inhaler, which was increasingly requested for industrial work. In 1854 the Scottish chemist John Stenhouse he had a brilliant idea, and incorporated a filter with powdered charcoal between two sheets of metal gauze. Twenty years later the Irish physicist John Tyndall added lime and glycerin to the carbon filter, and at least thirty years of research into the most effective chemical filters followed. Carbon later became the protagonist of filters, thanks to its high absorption capacity. In fact, inside there are small filter holes that prevent the passage of toxic gases.

Also in the 1870s, the British inventor Samuel Barton he added a rubber and metal visor with glass eyepieces and a rubber-coated hood. However, the glass and mica used for the eyepieces were fragile and often had to be replaced. For this reason they were replaced by Triplex lenses – formed by an intermediate lens in cellulose acetate inserted between two glass lenses which was much more resistant – which would later be replaced by polycarbonate lenses.

War use: the gas mask in the First World War

It was with the WWI that things began to change. The mask was no longer so useful for industrial purposes, but for defense against the enemy. The need to mass-produce gas masks for war purposes was clear to all states following the second Battle of Ypres (April 22, 1915), in which for the first time the Germans used mustard gas to exterminate Allied troops.

After this terrible day the troops were given cotton balls wrapped in muslin, later replaced by Black Veil Respirator invented by John Scott Haldane, which was a cotton ball soaked in an absorbent solution to be fixed on the mouth using a black cotton veil. It was the colonel Cluny MacPherson to make a canvas hood that absorbed chemicals and fit over the entire head. The hood – a khaki flannel bag – was soaked in a solution of glycerin and sodium thiosulfate and had a clear mica eyepiece rectangle. The design was adopted by the British Army and introduced as “Hypo helmet” (also known as British Smoke Hood) in June 1915.

In the autumn of that year that the first cylinder gas mask, which had a tin can containing the absorbent materials via a tube. Its compact version, the Small Box Respiratorwas the most requested during the war starting from August 1916.

British soldier with the Small Box Respirator. Credits: WG. MacPherson, W. P. Herringham, T. R. Elliott, A. Balfour

The Germans, who were more on the offensive than the defensive front, tried to develop new, increasingly lethal toxic gases, and the English could only continually raise the bar. At the end of 1917, they fought each other with millions of projectiles containing mustard gas and arsenic-based compounds. and for the Germans the reduced quantity of gas devices became particularly problematic, given that they lacked leather, rubber and manpower to provide effective gas masks in the final years of the war.

Meanwhile, since coal was not always available in large quantities, another source for absorbing poisonous gases was discovered: charcoal obtained from the shells and seeds of some fruits. That's how it was chestnuts, horse chestnuts and peach and plum stones were collected collectively and conveyed to recycling centers for war purposes.

Towards the modern gas mask

During the Second World War there was no shortage of innovations, in particular the Anti Gas (Light) English of 1943, which was made of plastic and was much more manageable than those of '15-'18. It was much more comfortable and adherent to the face, but above all it had a filter container which, like the lenses, was easily replaceable.

Anti Gas Mask (Light). Credits: Australian War Memorial

Some gas masks of the time in fact contained asbestos inside the filtersbecause at the time it was not thought to be harmful.

From those dark times onwards, the need to improve this device to protect against increasingly dangerous threats was evident. However, it was also clear that it offered protection only against respiratory absorption and that for total protection in the event of an attack with nuclear, biological or chemical agents had to be used with full protective clothing.

Despite the availability of these tools and training in their use, it appeared that troops forced to operate with these devices they were less efficient compared to others, and they tired easily. Thus it was that during the Cold War there were various innovations to make masks more comfortable and less tiring.

How gas masks work today

Today professional gas masks are used not only for war purposes, but also as personal protective equipment in all those cases in which particulates or chemical substances harmful to health are present in the air, for example during interventions by the Fire Brigade, for the disposal of toxic waste or for those who work in particular places such as mines, factories and so on.

There are gas masks of various types, and in all of them they have been included anti-particulate filters, as many hazardous materials disperse in the form of small particles. Thanks to adjustable strapsmodern masks are much more comfortable than those of the past, and some models even contain drinking tubes (connected to a water bottle).

Modern devices have two lenses (generally made of silicate glass) to protect the eyes, and for those with vision problems it is even possible to insert corrective lenses. Near the mouth part, however, they have a activated carbon filter. The air filtration of modern masks can be assisted by a small air pump, but it is only possible if there is enough oxygen. If ventilation is poor or if you are working in close contact with asphyxiating or unknown substances, air filtration is not possible, and therefore must be provided by a pressurized cylinder (as in scuba diving).