Seven out of 20 mesh samples collected from Wang Fuk Court failed to meet flame-retardant standards, Hong Kong Chief Secretary for Administration Eric Chan Kwok-ki revealed during a media briefing on Monday.

Over the past two days, mesh samples were collected from 20 different locations within four buildings of Wang Fuk Court. Among these, seven samples failed to meet flame-retardant standards, Chan added.

Hong Kong Secretary for Security Chris Tang Ping-keung stated that, on the second day after the fire, samples were taken from areas unaffected by the flames for testing, and those samples met the required standards at the time.

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This time, however, 20 samples were collected from various parts of the buildings, including areas where firefighters had to climb out of windows to reach—locations that were more difficult to access.

Testing revealed that samples taken from easily accessible locations were more likely to meet the standards, while those from harder-to-reach areas had a higher likelihood of failing.

Tang believes the fire spread was due in part to the mesh failing to meet flame-retardant standards, compounded by the use of foam materials. He suspects that substandard mesh may have been mixed in with compliant mesh.