Barcelona - Fifty-five people became sick Monday after inhaling an unidentified substance at an industrial park outside Barcelona, the fire service said.

Most of those treated for vomiting and sore eyes worked at a factory producing DVDs and CDs, according to the interior ministry of the regional Catalan government said.

A health alert was first issued at around 6:20 am local time (0420 GMT) at the Rubi industrial park in a suburb of Barcelona when workers noticed a strong odour and some became sick.



None of the businesses at the site have reported accidents involving chemicals, and experts from the regional environment ministry are still conducting tests to determine the cause, a fire service spokesman said.

He added, however, that the fire service suspected that the gas was chlorine.

The 55 people affected were treated at the site or in hospital, from where most had been discharged, and the area has "returned to normal," the spokesman said.