Overall, costs of air pollution from carbon-based sources are orders of magnitude higher than those from non-carbon-based ones, and the air pollution costs of coal-based electricity are much higher than those from other carbon-based fuels (see Table 5.1 below). From 2005 until 2014, S02 emissions from electricity generators under the US Environmental Protection Agency’s trading programmes have thus fallen by 69% from approximately 10 million tonnes to 3 Mt and NOx emissions by 55% from approximately 3.6 Mt to 1.6 Mt in the same time frame. In comparison, road transport accounts for 53 000 deaths per year. The electricity sector also accounts for 38% of NH3 (ammonia) emissions and 70% of S02 (sulphur dioxide) emissions.