Sulfur dioxide is the major cause of acid rain, a well-publicized phenomenon that degrades trees, crops, water, soil, and buildings and monuments. SO2 can also increase the level of inhalable particulates if it undergoes certain atmospheric reactions.
The sulfur dioxide indicator included in the 2008 EPI is based on estimates of emissions compiled by the Netherlands Environment Assessment Agency’s Emission Database for Global Atmospheric Research (EDGAR). This database contains global emissions inventories of greenhouse gases from anthropogenic sources measured in the year 2000.
There are no internationally agreed standards for sulfur dioxide emissions, and the development of uniform sulfur dioxide emissions targets is controversial for several reasons. First, local concentrations of sulfur dioxide can still be high in areas with uniform emissions, because migration of sulfur dioxide from outside sources can significantly influence local pollution levels. Second, different ecosystems have different tolerance thresholds to sulfur dioxide. Consequently, a given uniform emissions target can be too stringent for some localities while too lax for others. After consulting with experts on this issue, our target for the 2008 EPI is 0 sulfur dioxide emissions.
