Hong kong tear gas?
In fact there is a chemical composition of chloroform and nytric acid called Chloropcrin in tear gas which causes eye burning while tear gas cells are burst.
Tear gas is actually not a gas, but the vapor of a crystal. The two most common are CN and CS. When heated, or blown about in a fine powder, they cause a burning sensation sensation to the skin, eyes, and lungs. OC is an extract of the oil found in hot peppers, and is commonly used in self defense sprays.