"...Foam sofa stuffing banned in Britain and the USA was the catalyst for the Mei Foo blaze which killed nine people last April, a government chemist said. Cheung told the inquest that the toxic smoke produced by burning Polyurethane Foam also contributed to the deaths of the victims.....

...Once polyurethane form is involved with fire, it prduces toxic, smelly smoke.....

..."If the sofa had been made of some other material that could not be so easily ignited by a cigarette, this tragedy would not have happened so easily...... " (SCMP on 14th march 1998)

Therefore, the killer was POLYURETHANE FORM.