London - A mysterious chemical haze that left scores of people on the English coast with streaming eyes, sore throats and breathing problems has dissipated, but its cause remains a mystery, police and emergency services said Monday.

The gas cloud appeared Sunday, sending people fleeing from the beach and cliffs at Birling Gap, a popular coastal spot 60 miles (100 kilometers) south of London.

Life boats were dispatched to help clear people from the beaches there, and Eastbourne District General Hospital said it had treated more than 130 people. Sussex Police said the injuries were mostly minor.

"Whatever it was, it smelled like burnt plastic," said Bob Jefferey of the Royal National Lifeboat Institution's Eastbourne division. "It hung about and didn't move yesterday because there was no wind. The cloud seems to have dispersed today, though."

Pollution has been known to drift to Britain from industrial plants in France, but police said the wind direction made that unlikely in this case.