Toxic cloud Spain

Catalan police officers are seen wearing gas masks after an explosion at a chemical plant caused a toxic cloud to spread over Igualada near Barcelona, February 12, 2015. REUTERS/Stringer

An orange toxic cloud is seen over the town of Igualada, near Barcelona, following an explosion in a chemical plant, February 12, 2015. REUTERS/Ricard Sole Figueras

An orange toxic cloud is seen over the town of Igualada, near Barcelona following an explosion in a chemical plant, February 12, 2015. Three people were injured in the explosion at the chemical plant in northern Spain on Thursday and authorities advised residents of several small towns near Barcelona to stay indoors as the large toxic cloud spread over the area. REUTERS/Paula Arias

An orange toxic cloud is seen over the town of Igualada, near Barcelona, following an explosion in a chemical plant, February 12, 2015. REUTERS/Alba Aribau

A Catalan police officer wearing a gas mask speaks on a mobile phone after an explosion at a chemical plant caused a toxic cloud to spread over Igualada near Barcelona, February 12, 2015. REUTERS/Stringer

An orange toxic cloud is seen over the town of Igualada, near Barcelona following an explosion in a chemical plant, February 12, 2015. REUTERS/Paula Arias

Fire-fighters, some wearing gas masks, leave the Simar chemical plant where an explosion occurred in Igualada near Barcelona, February 12, 2015. REUTERS/Stringer

An orange toxic cloud is seen over the town of Igualada, near Barcelona, following an explosion in a chemical plant, February 12, 2015. REUTERS/Ricard Sole Figueras

People wearing masks walk in the streets after an explosion at a chemical plant caused a toxic cloud to spread over Igualada near Barcelona, February 12, 2015. REUTERS/Stringer

A police officer wearing a mask speaks with a woman on a blocked-off street after an explosion at a chemical plant caused a toxic cloud to spread over Igualada near Barcelona, February 12, 2015. REUTERS/Albert Gea

Fire-fighters, some wearing gas masks, leave the Simar chemical plant where an explosion occurred in Igualada near Barcelona, February 12, 2015. REUTERS/Stringer

An orange toxic cloud is seen over the town of Igualada, near Barcelona, following an explosion in a chemical plant, February 12, 2015. REUTERS/Paula Arias