<P> The distribution of gas cloud casualties was not only limited to the front . Nearby towns were at risk from winds blowing the poison gases through . Civilians rarely had a warning system put into place to alert their neighbours of the danger . In addition to poor warning systems, civilians often did not have access to effective gas masks . Also, when the gas came to the towns over the wind, it could easily get into houses through open windows and doors . An estimated 100,000 - 260,000 civilian casualties were caused by chemical weapons during the conflict and tens of thousands (along with military personnel) died from scarring of the lungs, skin damage, and cerebral damage in the years after the conflict ended . Many commanders on both sides knew that such weapon would cause major harm to civilians as wind would blow poison gases into nearby civilian towns but nonetheless continued to use them throughout the war . British Field Marshal Sir Douglas Haig wrote in his diary: "My officers and I were aware that such weapon would cause harm to women and children living in nearby towns, as strong winds were common on the battlefront . However, because the weapon was to be directed against the enemy, none of us were overly concerned at all ." </P> <P> None of the First World War's combatants were prepared for the introduction of poison gas as a weapon . Once gas was introduced, development of gas protection began and the process continued for much of the war producing a series of increasingly effective gas masks . </P> <P> Even at Second Ypres, Germany, still unsure of the weapon's effectiveness, only issued breathing masks to the engineers handling the gas . At Ypres a Canadian medical officer, who was also a chemist, quickly identified the gas as chlorine and recommended that the troops urinate on a cloth and hold it over their mouth and nose . The first official equipment issued was similarly crude; a pad of material, usually impregnated with a chemical, tied over the lower face . To protect the eyes from tear gas, soldiers were issued with gas goggles . </P> <P> The next advance was the introduction of the gas helmet--basically a bag placed over the head . The fabric of the bag was impregnated with a chemical to neutralize the gas--however, the chemical would wash out into the soldier's eyes whenever it rained . Eye - pieces, which were prone to fog up, were initially made from talc . When going into combat, gas helmets were typically worn rolled up on top of the head, to be pulled down and secured about the neck when the gas alarm was given . The first British version was the Hypo helmet, the fabric of which was soaked in sodium hyposulfite (commonly known as "hypo"). The British P gas helmet, partially effective against phosgene and with which all infantry were equipped with at Loos, was impregnated with sodium phenolate . A mouthpiece was added through which the wearer would breathe out to prevent carbon dioxide build - up . The adjutant of the 1 / 23rd Battalion, The London Regiment, recalled his experience of the P helmet at Loos: </P>

How many types of poison gas was used in ww1