About 185 people were injured in the blast, which gutted a wheel hub polishing workshop owned by Kunshan Zhongrong Metal Products Co., Ltd. In Kunshan City on Saturday.
Yang Dongliang, director of the State Administration of Work Safety and head of an investigation team for the accident, said questions arising from the accident and initial investigation suggested that the factory had long failed to address related risks and problems, state-run Xinhua news agency reported.
There was "very serious dereliction of duty," given the excessive metal dust inside the workshop, which was ignited by flames and caused the blast, Yang told a meeting of the investigation team.
Yang said the main reasons behind the accident was that design and construction of the factory buildings had failed to conform to safety provisions.
He said the?workshop was overcrowded with too many processing assembly lines. There was a shortage of dust removal equipment at the site. Also there was substandard electrical equipment at the factory site.
Work safety measures had not been strictly implemented. Accumulated dust and powdered metals had not been cleaned in a timely manner, which led to the combustion of particles, he said.
In factories and mines, the fast combustion of particles suspended in air in an enclosed space can result in a dust explosion.
Yang said Kunshan Zhongrong shoulders major responsibility for the accident and local government departments were also to blame for poor implementation of regulations.