Every year billions of dollars "go up in smoke" as oil and gas companies burn off unwanted natural gas.

The controversial practice, called gas flaring, reduces the chance of the gas exploding. But it produces significant greenhouse-gas emissions at a time of growing concern over climate warming.

The World Bank estimates that about $30bn worth of gas is burned off every year, which is equivalent to 30 per cent of the European Union's annual gas consumption.

The world's largest gas-flaring operations are in the Niger Delta, where communities are complaining of chronic health problems and pollution.

Al Jazeera's Yvonne Ndege reports.

Source: Al Jazeera