Since 2000 Europe has experienced a steady decline in PM2.5 levels, slightly more than the USA.

Annual changes in OMI NOx emissions (2005-2008)

Annual changes in concentrations of NO2 in the period 2001–2010 in Europe.
The data presented were derived from a consistent set of ground stations in all years. Statistically significant trends (level of significance 0.1) are calculated by applying the Mann-Kendall test. Increasing concentrations are indicated with red dots and decreasing concentrations with green dots, when statistically significant.

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