A CLOUD of toxic gas hovered over an industrial estate close to homes after a chemical spillage yesterday.

The dangerous yellow nitric acid fumes floated over the top of Johnson Matthey Catalysts, in Clitheroe, for more than seven hours as dozens of firefighters used sprays to dilute it.

Firefighters said the cloud, which was around 100 sq metres, was ‘potentially lethal’ because the chemical was highly flammable.

If breathed in it could have caused burning in the throat and lungs, they said.

Hundreds of workers were evacuated from the site just before midday yesterday and it is understood a nearby nursery was also cleared as a safety precaution.

Two investigations are under way by the company and the fire service and the Health and Safety Executive has been called in.

Local MP Nigel Evans said the incident was ‘clearly very worrying’ and called for a public explanation of what went wrong.

Residents said they were ‘bemused’ by the commotion and felt they had been ‘very lucky’ the cloud had not drifted because it was a still day.

The alarm was sounded at 11.30am, when liquid nitric acid leaked inside the five-storey plant, where catalysts are manufactured.

It is not yet known how the highly corrosive acid leaked out from a pipeline.

Incident commander Barry Hornsby, of Nelson fire station, said: “It was a big leak that produced a big gas cloud.

"Our concerns were nearby schools and businesses. It’s potentially lethal, because it is flammable.

"But fortunately because of the quick work of the crews we were able to control it.”

The spill was contained but because of its strength, it reacted with the surroundings materials, which included metal, and the gas was released.

Firefighters said it was lucky the wind direction did not take it towards nearby houses. No-one was injured in the incident.

Ribble Valley MP Mr Evans said: “In 19 years I have never known anything like this before.

“Clearly it is very concerning, and I shall be contacting the management to ask what exactly went wrong.

“It is extremely worrying for the people working there, and living nearby.

"People need reassurances that this sort of thing will not happen again.”

The Health and Safety Executive confirmed it was ‘making inquiries’ into the incident before deciding whether to investigate.

Residents said they were concerned to find out about the gas cloud with one woman initially believing it was ‘a drill’.

Pimlico Village resident Maureen Cooper said: “It sounds like we were lucky. We didn’t know anything about it. We saw the fire engines, but had no idea what was going on.”

A neighbour, who asked not to be named, said: “From here you couldn’t see anything.

"But when I was over the other side earlier today you could see a yellow cloud of gas hanging over the site.”

Another said her child had been evacuated from a near-by nursery.

Around 175 workers fled the plant, and 70 firefighters, in 10 vehicles, were called to deal with the incident.

Wearing breathing apparatus and chemical protection suits, they stopped the leak before diluting the cloud without the toxic gas reaching ground level.

In a statement, Johnson Matthey confirmed the spillage, which resulted ‘in the release of a yellow coloured plume to the atmosphere.

The company added: “No employees were exposed, affected, or injured.”

The company also thanked the emergency services for their efforts.