A Chinese University expert has called on the government to install more greenery in the city to help people living in cramped and poorly-ventilated environments cool themselves down during the hot summer nights.
Last month, the “very hot weather warning” was in force for 467 consecutive hours, or 20 days – the longest since the introduction of the warning in 2000 – and the city also recorded a record-breaking 21 “hot nights” in July, when the minimum temperature was above 28 degrees Celsius.
Dr Kevin Lau, a research assistant professor from the Institute of Future Cities at Chinese University, said global warming coupled with the compact and high-density urban design are to blame for the increase in the number of hot nights.
The study also found that consecutive hot nights were more detrimental to human health than hot weather during the day.
Ren Chao, an associate professor from the University of Hong Kong’s Faculty of Architecture who also participated in the research, said that people’s sleep could be badly disrupted by the heat for a prolonged period of time, which could lead to a wide range of health problems or even death.
She said females and elderly people are most vulnerable. The physical attributes of the female body mean they aren't as good in regulating their body temperature.
"If this hot night continues, then you can imagine if you cannot sleep very well, for one night it's ok, but for several nights then you'll definitely feel very exhausted during the daytime," said Ren.
"For the normal people you may survive, but for elderly people eventually if their body system cannot sustain [it] may cause the deaths."
Ren said those who live in cramped and poorly-ventilated areas like subdivided flats or caged homes are most affected by the heat, and urged them to do more to cool themselves down, like opening windows, drinking more water or wiping their bodies with cool wet towels.
Lau stressed the government needs to tackle the problem by enhancing the city’s built environment by increasing the amount of greenery in the city, for example by planting trees and providing parks.
"But at the same time, given the compact environment, I think (we can) increase the greenery coverage, for example, by using vertical greenery, podium gardens and to replace existing... street structures," Lau said. "It is a matter of how you design the greening to provide these opportunities to relieve the heat."
In the longer run, he said, it is also important to improve urban ventilation through better town planning.