The U.S. Park Police denied using tear gas but used a pepper compound, which the CDC and other organizations list as one form of tear gas.
Federal institutions such as the Centers for Disease Control and Prevention (CDC) and the U.S. Army Medical Research Institute of Chemical Defense have listed tear gas as the common term for riot-control agents. Whether the common or formal term is used, the effects on people are the same. Protestors who were exposed to the pepper compound coughed and gagged as they scattered, their eyes red and streaming in some cases. These are all symptoms of exposure to tear gas. The Handbook of Toxicology of Chemical Warfare Agents uses 'tear gas' as an informal umbrella term for riot-control agents, and also cites pepper spray as tear gas. Therefore the claim is true because even the use of a pepper compound which irritates eyes and skin is a form of tear gas.