Hong Kong's deadliest fire in three decades has spotlighted its risky use of flammable bamboo scaffolding and mesh for building work, in a tradition dating back centuries to mainland China.
Firefighters are still working to extinguish the fire that tore through residential high-rise buildings in the city, where at least 55 people were killed, and hundreds more remain missing.
The cause was initially unclear, but video from the scene showed how rapidly the flames leapt across the green protective netting and sent bamboo lattices crashing to the ground in flames.
Authorities said they had doused the flames in four of seven affected blocks.
On Thursday, police told local media that early findings point to the protective mesh and plastic coverings of the buildings, which may fall short of fire standards.
They found foam material sealing some windows on one unaffected building, and installed by a construction company engaged in year-long maintenance work.
Kristof Crolla from the University of Hong Kong's Department of Architecture said he was stunned at how quickly the blaze moved.
"Hong Kong has over 7,500 towers, and most have been built with bamboo scaffolding, and we never see fires like this," he told the ABC.
Bamboo, he added, is far harder to ignite than many assume.
"Bamboo doesn't burn as easily as wood; it's very hard to ignite, so probably some other materials triggered the blaze," Professor Crolla added.
Why does Hong Kong still use bamboo scaffolding?
For decades in the skyscraper-strewn former British colony, bamboo has been the material of choice for scaffolding — cheap, abundant and flexible — bound together with nylon cords.
The craft originated on mainland China, where bamboo has been a cornerstone of architecture since ancient times, even reputedly used for scaffolding and tools in the building of the Great Wall.
Now, however, it has largely been phased out there for sturdier metal scaffolding and clamps.
But Hong Kong, despite its modernity, still has about 2,500 registered bamboo scaffolding masters plying their trade, according to official figures.
The number of metal scaffolders is about triple that.
Small teams of scaffolders scrambling up steep gleaming facades to sheathe a building in a matter of weeks is an iconic sight in the global financial hub.
The bamboo lattices are also often used alongside green construction mesh to prevent debris from injuring passers-by, as was the case in the tower blocks at the Wang Fuk Court housing complex in Hong Kong's northern Tai Po district.
Hong Kong's leader, John Lee, said a task force had been set up to investigate the cause of the blaze.
Police have arrested two directors and an engineering consultant of the company on suspicion of manslaughter over the fire.
Scaffolding checks promised
Mr Lee also said the government would take special action against ongoing projects, checking whether scaffolding mesh materials met fire retardant standards and other safety standards.
In March, the government said 50 per cent of new public works contracts would be required to use metal scaffolding going forward.
But the emphasis appeared to be more on worker safety rather than fire risks.
There were 22 deaths involving bamboo scaffolders between 2019 and 2024, according to official figures.
Despite the safety push, Hong Kong's secretary for labour, Chris Sun, said in July that "the government has no intention to ban the use of bamboo scaffolds at the moment".
The Association for the Rights of Industrial Accident Victims in Hong Kong said in a Facebook post that there had been at least two other fires involving bamboo scaffolding this year.
Protective nets, screens and tarpaulin or plastic sheeting installed on the face of scaffolding "should have appropriate fire retardant properties in compliance with a recognised standard'', says the Hong Kong Labour Department's Code of Practice for Bamboo Scaffolding Safety.
Jason Poon, a whistleblower who has previously exposed shoddy construction work in Hong Kong, said in a Facebook post on Wednesday that fire hazard risks existed in scaffolding at many housing complexes.
He said he had reached out to various government departments last year concerning the lack of fire retardant in scaffolding nets at another complex, but he was ignored.
Reuters received no immediate response from the fire, buildings and labour departments to a request to comment.
ABC/Reuters