Convergence Analysis of Outdoor Air Pollution for Nitrogen Dioxide for 179 Countries

Using yearly nitrogen dioxide pollution measures in parts per billion for 179 countries during 1979 to 2011, this research examines whether the convergence process of catch-ups has taken place among countries in both total as well as in multiple subgroups of countries. All four income subgroups and six regional subgroups displayed their convergence of catch-ups in support of the catch-up process displayed by the total group. The most important finding is that the subgroups with lower NO2 pollution levels did display three to five times faster speed of catch-ups in comparison to the subgroups with higher NO2 pollution. Policy Implications to these findings will be discussed.