Units: 1000 Metric Tons/Sq. Km. of Populated Land Area
Units: We obtained the total emissions for each country by summarizing emissions data, originally available as a grid map with 1 degree x 1 degree cells. Air pollution is generally greatest in densely populated areas. To take this into account, we used the Gridded Population of the World dataset available from CIESIN and calculated the total land area in each country inhabited with a population density of greater than 5 persons per sq. km. We then used this land area as a denominator for the emissions data.