<P> In the first combined chlorine--phosgene attack by Germany, against British troops at Wieltje near Ypres, Belgium on 19 December 1915, 88 tons of the gas were released from cylinders causing 1069 casualties and 69 deaths . The British P gas helmet, issued at the time, was impregnated with sodium phenolate and partially effective against phosgene . The modified PH Gas Helmet, which was impregnated with phenate hexamine and hexamethylene tetramine (urotropine) to improve the protection against phosgene, was issued in January 1916 . </P> <P> Around 36,600 tons of phosgene were manufactured during the war, out of a total of 190,000 tons for all chemical weapons, making it second only to chlorine (93,800 tons) in the quantity manufactured: </P> <Ul> <Li> Germany 18,100 tons </Li> <Li> France 15,700 tons </Li> <Li> United Kingdom 1,400 tons (also used French stocks) </Li> <Li> United States 1,400 tons (also used French stocks) </Li> </Ul> <Li> Germany 18,100 tons </Li>

What types of gases were used in ww1