Rising temperatures

Last year, temperatures of 28 C or higher were recorded on 41 nights, the highest number in the city's recorded history. Moreover, during the afternoon of Aug 22－the day before Typhoon Hato struck－the temperature rocketed to 36.6 C, a record high.

The temperature in Hong Kong has risen by 0.15 C every decade since 1987. Unless greenhouse gas emissions are sharply curbed, the city's annual mean temperature is expected to rise by about 1.5 C to 3 C by 2060, and by 3 C to 6 C by 2100.

A study by 24 international academic institutions and organizations found that the greater frequency of heat waves and their longer durations exposed an additional 125 million people worldwide to greater health risks between 2000 and 2016.

It also found that people under prolonged exposure to high temperatures were more prone to heat stress, heatstroke, and aggravated cardiovascular and renal conditions. Moreover, the poor are at greatest risk.

Lee, at the lower end of the social scale, may not know the statistics, but he knows he was sick last summer, when he was hospitalized with summer flu for several nights.

"I have never seen hotter days than during last summer," he said. "I always found myself lying on the bed, heaving, sweating, unable to sleep, dizzy and very uncomfortable."

Chan's research discovered an overall 4.5 percent rise in hospital admissions from 1998 to 2009 when the daily mean temperature rose 1 degree above the 28.5 C threshold.

"Wealthier families can afford air-conditioning, but poor families can't," she said.