Taken from the Economist magazine, 04 December 2008

"If user demand were the sole driver of innovation, the biomass cooking stove would be one of the most sophisticated devices in the world. Depending on which development agency you ask, between two-and-a-half and three billion people—nearly half the world’s population—use a stove every day, in conjunction with solid fuel such as wood, dung or coal. Yet in many parts of the world the stove has barely progressed beyond the Stone Age.

The World Health Organisation (WHO) estimates that toxic emissions from cooking stoves are responsible for causing 1.6m premature deaths a year, half of them among children under five years old. In China 83m people will die from lung cancer and respiratory disease over the next 25 years, according to a recent report from Harvard University. Research from the University of California, Berkeley, on stoves in India, Guatemala and Mexico has found links between indoor air-pollution from stoves and increased incidence of pneumonia, cataracts and tuberculosis.

After an initial wave of stove design that sought to reduce deforestation through improved efficiency, scientists and engineers have turned their attention to stoves that minimise the levels of noxious emissions to which stove users—mainly women and children—are exposed. Crucially, they have also recognised the need to take account of the way in which stoves are actually used.

And even the best stoves will always be less effective in the field than they are in the lab, says Kirk Smith, an expert on the impact of stove air-pollution on health. In a field where a large number of development projects are chasing small amounts of funding, getting solid data is essential for making the necessary improvements, he says. In parallel with the advances in the stoves themselves, researchers are therefore finding more precise ways to measure usage and pollution, including the placement of battery-powered heat sensors in users’ homes and the use of particulate monitors with data storage. “You don’t get what you expect—you get what you inspect,” says Dr Smith. It is a lesson that many in the field are belatedly learning."

Read the report here in full