Dynamic Trends of NO₂ Concentrations among 109 Countries

Abstract

Nitrogen Oxide (NO₂) is a major constituent of the air pollution mix. Many countries in the world have been experiencing varying rate of change in their Nitrogen Dioxide Concentration (NO₂C). The dynamic change of NO₂C in this study is analyzed by the progress ratio (PR) from an experience curve (EC). Involving 109 countries during the period of 2000 to 2014. The average PR for the total 109 countries is 105.1% which indicates a difficult challenge of reducing future NO₂C for the world. Because each doubling of the cumulative energy consumption for this group has increased NO₂C by 5.1%. However, PRs for individual countries vary a great deal from 55.57% to 187.96% suggesting that the degree of challenge varies a great deal by countries. A slight majority of 55 countries displayed a decreasing trend of NO₂C with an averaged PR of 87.64%. However, a large minority of 54 countries displayed an increasing trend with an average PR of 122.88%. Analysis by two different types of classical and kinked EC indicate a minority of 53 countries display a classical experience curve with the average PR of 97.22%, while the remaining 56 countries display a kinked experience curve with the average PR of 112.55%. Among the 54 countries displaying an increasing trend, 37 countries display a kinked slope with the averaged PR of 130.2%, whereas the remaining 17 countries display a classical slope with the average PR of 106.96%. Analysis of type of slope and trend of EC suggest the chance of a major improvement of the future NO₂C as follows: (1) First, the 17 countries with increasing classical slope;, (2) the 37 countries with increasing kinked slope;, (3) the 36 countries with decreasing classical slope; and (4) the 19 countries with decreasing kinked slope. Further implications are discussed.

Keywords: Nitrogen Dioxide Concentration (NO₂C), progress ratio, classical experience curve, kinked experience curve