Postcard from... Los Angeles

Something is rotten in the State of California, where public safety experts are attempting to identify the source of a foul smell which is polluting Los Angeles and its suburbs.

The stench has prompted at least 200 emergency calls by residents. Most appear to be under the impression that either a sewage main has broken or a toxic spill occurred in their neighbourhood.

In fact, experts believe that the pungent aroma – part sulphur, part rotten eggs – is coming from the Salton Sea, a vast inland lake roughly 150 miles south-east of Los Angeles, where wildlife experts reported a widespread "fish die-off" last week.

Strong winds have added to the problem by churning up the relatively-shallow body of water.

That has in turn exposed portions of its bottom, which is covered in a layer of mud formed from several decades' worth of decaying plants, fish, and other animals.

The sea was formed by accident in 1905, when the Colorado River burst its banks. It measures 360 square miles, sits 200ft below sea level, is highly saline, and has been slowly evaporating in recent decades. That often exposes areas of bubbling mud which often cause localised sulphurous smells.

Whatever the source, the smell was bad enough for schools to have stopped pupils from going outdoors during breaktime. A spokesman for the Los Angeles Fire Department even hit the airwaves asking residents to stop calling 911.