The incident took place on 19 July, when an estimated 1.5 tonnes of 1,3-butadiene escaped from an emergency relief valve. The Agency says that the gas "dispersed within the confines of the Barry chemical complex" and had no effect on human health or the environment.
An Agency investigation revealed that the release occurred because of failings in Zeon's operation and maintenance procedures. The notice requires the company to introduce inspection and maintenance procedures for the polymerisation vessels, and to review and improve the design, maintenance and operation of all polymerisation activities on site by next September.
Surprisingly, the Agency's press statement described 1,3-butadiene merely as "an organic chemical", without mentioning that it is both extremely flammable and a category one carcinogen.