The BBC has reported an increase in leaks of SF6 (sulphur hexafluoride), widely used in the electrical industry to prevent short circuits that could lead to fires. 

 

The gas is cheap and non-flammable and is effective for insulating medium- and high-voltage electrical installations. However, it has around 23,000 times more global warming potential than carbon dioxide (CO2) and its effect in the atmosphere is likely to last for hundreds of years