Although tear gas is considered a non-lethal chemical weapon, exposure is still known to cause eye pain, chest tightness, coughing, vomiting, and increased nasal secretions, among other painful and uncomfortable symptoms. The use of tear gas in wartime combat was outlawed by nearly every country in the world in 1993, but U.S. law enforcement is still authorized to use it domestically during times of civil unrest. Just earlier this week, the Trump Administration ordered the use of tear gas outside of the White House against peaceful protesters coming together in support of the Black Lives Matter movement to clear the path for the president's photo op.