Emily is preparing for a typical night out in Hong Kong. In her tiny bedroom in one of the city’s countless high-rise apartments, the 33-year-old dresses head-to-toe in black and fills her backpack with the items she needs for the evening: gas mask, goggles, a towel, water, gloves and several stainless steel bowls.

A year ago, Emily, an executive assistant, spent her weekends playing basketball, going to church and volunteering at an aged-care home, but for the past three months, she has taken on a crucial and dangerous role in the Hong Kong protests: neutralising tear gas. As soon as the canisters hit the ground and other protesters start to run away, she steels herself, forcing her body to override its survival instinct and head straight towards the hissing white fumes.