The UN’s 1985 Helsinki Protocol on the Reduction of Sulphur Emissions was very effective. In the US between 1980 and 2013, annual average sulphur dioxide concentrations decreased by 87 per cent, while in Europe, sulphur dioxide emissions decreased by 76 per cent between 1990 and 2009. However, removing sulphur from fuel is expensive, meaning that lower-grade fuel including sulphur remains the norm in many developing countries and in international shipping.
Sulphur dioxide
