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How solar stoves cut cooking smoke

21 September 2010 Last updated at 17:33 BST

The US Secretary of State Hillary Clinton has announced a global partnership to tackle the scourge of toxic smoke from indoor cooking fires.

Cooking smoke is estimated to shorten the lives of 1.9 million people a year; it also contributes to climate change.

The BBC's Roger Harrabin shows how a cleaner solar stove works.