In the last period of the world war, suffocating gas shells dropped from an airplane began to be used more and more often. With the development of aviation technology, when the number of aircraft on the warring parties reaches a huge figure, this method of struggle becomes especially important. The airplane, due to its mobility, is very little vulnerable to enemy shots; high speed of movement allows flotillas of pilots to attack where the enemy does not expect an attack at all, for example, in the rear. Dropping bombs with slowly evaporating suffocating liquid, a flotilla of airplanes can not only harm the troops in the area of ​ ​ its action at the moment, but also make the attacked area impassable for quite a long time.