I saw that as an alternative but at least according to wikipedia:

According to Steinritz et al., "Due to its potential pulmonary toxicity," zinc chloride producing smoke grenades "have been discharged from the armory of most western countries (...)."

Despite its continued use by FPS (Federal Protective Services) as a riot control agent, the Department of Defense has begun to phase out the use of HC smoke after a 1994 report by the U.S. Army Biomedical Research and Development Laboratory due to ensure the safety of US soldiers, noting that, "Exposure of unprotected soldiers to high concentrations of HC smoke for even a few minutes has resulted in injuries and fatalities."

Leave it to the cops to use something the army is phasing out as too dangerous domestically on protestors