By Central Asia correspondent Louise Hidalgo

Researchers have discovered that contaminated dust from the Aral Sea has blown hundreds of kilometres across Central Asia, raising new concerns about the consequences for human health.

The study, by a team from the UK, found that some of the highest deposits from the old Aral seabed are in southern Turkmenistan, far away from the epicentre of what's been described as the world's worst man-made environmental disaster.

The researchers from Nottingham University say the devastating impact on human health needs to be urgently assessed.

For years now, people living around the Aral Sea have been suffering from the toxic cocktail of pesticides and salts that blow off the old seabed.

The Aral used to be the fourth largest inland sea in the world, but the Soviets siphoned off the waters that feed it to irrigate the vast cotton fields of Central Asia.

As a result, the Aral Sea shrank by almost half, leaving a toxic wasteland that has blighted the land and its people.

For the first time, this new study shows just how wide the area is of those affected by the polluted dust that now blows off the old seabed - and how deadly are the pesticides and salts they carry.

Health concerns

The researchers collected dust samples from as far away as Turkmenistan's border with Afghanistan, hundreds of kilometres to the south.

And worryingly, it was in the areas furthest away that they found the highest concentrations of dust.

Ian Small, the director of Medecins Sans Frontieres in Uzbekistan, said: "The region has one of the highest rates of acute respiratory infections in the world.

"It's estimated that, if and when the sea completely dries up, there will be 15 billion tonnes of salt liberated into the environment.

"So clearly, the problem is getting worse and we need to determine what is the human health effect."

Already it has been suggested that the toxic dust from the Aral has been carried as far as the Himalayas and Belarus.

There are also concerns that the high salt content is contributing to the melting of glaciers high in the Pamir Mountains, where Central Asia meets Afghanistan and from where the rivers that feed the Aral Sea flow.