At a bustling fruit store in Hong Kong’s Causeway Bay, a crowd of workers sporting damp towels around their necks or fan vests buy up chilled drinks to stay hydrated as temperatures hit 32 degrees Celsius (89.6 Fahrenheit) on a busy weekday morning. Soaked in sweat, 29-year-old construction worker Yau is among those buying a litre of water to help beat the heat on Wednesday. “I spend at least HK$100 per day to buy water these days. It is expensive, and I get poor just drinking water to survive...