This report examines global emissions of major air pollutants (SO2, NOx, PM2.5) resulting from energy scenarios developed for the World Energy Outlook 2009 (OECD/IEA, 2009). Estimates include emissions for 27 regions according to the aggregation used in the IEA World Energy Model (WEM). Emissions have been estimated using the IIASA GAINS model. 

The 2009 Outlook discusses two energy pathways for the next 20 years: the Reference Scenario that reflects unchanged governmental energy and climate policies and the 450 Scenario, which assumes implementation of climate policies that allow limitation of the increase in global average temperature to about 2 degrees C. These pathways were implemented into the GAINS model. Next, emissions of air pollutants were calculated. Calculations take into account the current air pollution control policies in each country or region as adopted or in the pipeline by mid-2009. 

Presented in this report estimates do not include emissions from international shipping as well as cruising emissions from aviation. They also do not include emissions from biomass burning (deforestation, savannah burning, and vegetation fires). 

In 2005, world emissions of SO2 from sources covered in this report were about 95 million tons. OECD countries contributed 30 percent of this total. Implementation of current policies on air pollution control for the Reference Scenario causes a 14 percent decrease in world emissions of SO2 in 2020 compared with 2005, which is a result of more than halving of emissions from the OECD countries and a moderate decrease in other countries. After 2020 emissions from the non-OECD countries start to rise, which causes an increase of world emissions by about four million tons until 2030. The corresponding world emissions of NOx are: 85 million tons in 2005 (of which 43 percent originated from the OECD countries), decrease until 2020 by 13 percent and next increase until 2030 by about 10 million tons. Emissions of PM2.5 (38.5 million tons in 2005) are dominated by the sources from non-OECD countries  90 percent of total. In 2020 and 2030 the world emissions are by 3-4 percent higher, which is again due to the increase of emissions from the non-OECD countries. 

The 450 Scenario causes an important reduction in emissions of air pollutants. By 2030, the emissions of SO2 are 29 percent lower than in the Reference case. Emissions of NOx decrease by 19 percent and those of PM2.5 by nine percent. 

Costs of the current policy air pollution controls are about 155 billion Euros/a in 2005. Until 2030 these costs increase in the Reference Scenario by a factor of three, which is due to higher activity levels and increasing stringency of controls. In 2030, more than 60 percent of the total control costs are the expenditures on reducing emissions from road transport. The 450 Scenario brings 17 percent cost savings in 2030 compared with the Reference. 

The Study also estimated health impacts of air pollution in Europe, China and India in terms of life years lost (YOLLs) attributable to the exposure from anthropogenic emissions of PM2.5. In 2005 about 3.4 billion of life-years were lost in those countries due to PM exposure. This estimate is dominated by impacts in China and India, which together contribute more than 90 percent of YOLLs in 2005. The Reference Scenario implies an increase of the YOLLs indicator in 2030 by about 70 percent to 5.7 billion. The 450 Scenario saves 1.2 billion life-years in 2030. 

Lower impact indicators and lower air pollution control costs in the 450 Scenario compared with the Reference clearly demonstrate important co-benefits of climate policies for air pollution.