During weeks of often violent protests in Hong Kong, police have fired thousands of rounds of tear gas to disperse anti-government protesters. Tear gas is essentially a “chemical weapon”, irritates mucous membranes to cause crying, sneezing, coughing and breathing difficulties. But how might tear gas might affect bystanders as well as protesters in a densely populated city like Hong Kong? Doctor David Hui, the Stanley Ho Professor of Respiratory Medicine at the Chinese University of Hong…
