Hong Kong's army of volunteers disinfects the city, house by house

Gillian Wong, a petite, semiretired accountant in her sixties, leads the way into the dilapidated buildings, her eyes struggling to adjust to the dim light. Yan, a kindergarten teacher, follows, her bag weighed down by a 5-liter bottle of alcohol rub. The last member, Keith Tse, a construction worker on leave due to a leg injury, comes late but well-prepared, carrying a portable fan in one hand and a torch on his head. Both soon come in useful as the trio trudge up the stuffy, narrow stairways of the old tong lau -- tenement buildings -- of Sham Shui Po in Hong Kong.