There are large decreases in OMI NO2 levels from 2005 to 2016 over European cities, which are due to tightening vehicle emission standards. The largest decreases (−45-−55%) occur over the major cities of the Iberian Peninsula (Madrid and Barcelona (Spain), Lisbon (Portugal)) and Athens (Greece). Some of the decrease in Spain and Greece may have occurred as their economies have been slow to recover after the global economic recession that began in 2008. Large decreases occurred over other major cities, such as Paris, London (United Kingdom), Moscow (Russia), and those in the Ne
Jacques Descloitres, MODIS Rapid Response Team, NASA/GSFC.