Preliminary investigation reveals accident was caused by overloaded truck.
The accident was caused by a flat tyre on the bus.
Six employees from the Jiangsu Tianjiayi Chemical company have "major responsibilities" in relation to the incident, the Yancheng government said.
The China chemical blast death toll has risen to 44, while 90 others have been seriously injured.
The mills suspended operations amid local authority orders to shut plants until they meet anti-pollution rules.
Jiangsu Governor Wu Zhenglong said that higher standards and stricter strategies would be implemented to reduce the amount of smog in the province.