The evolution of nitrogen dioxide (NO2) over Spain from 1996 to 2012 has been analyzed by a group of scientists led by the Atmospheric Chemistry and Climate Group (AC2) at IQFR (CSIC), with the participation of the University of Bremen, the University of Castilla-La Mancha (UCLM) and the National Institute for Aerospace Technology (INTA).

The study is focused ondensely populated cities of Barcelona, Bilbao, Madrid, Sevilla and Valencia, employing 17 years of NO2 measurements, from 1996 to 2012. This data series combines observations from in-situ air quality monitoring networks and the satellite-based instruments GOME and SCIAMACHY. The results in these five cities show a smooth decrease in the NO2 concentrations of 2% per year in the period 1996-2008, due to the implementation of emissions control environmental legislation, and a more abrupt descend of ~7% per year from 2008 to 2012 as a consequence of the economic recession. In the whole Spanish territory the NO2 levels have decreased by ~22% from 1996 to 2012. In some cities, e.g. Madrid, the decrease in NO2 concentrations surpasses 40%. Statistical analysis of several economic indicators is used to investigate the different factors driving the NO2 concentration trends over Spain during the last two decades.

The work has been published in Scientific Reports

C.A. Cuevas, A. Notario, J.A. Adame, A. Hilboll, A. Richter, J.P. Burrows and A. Saiz-Lopez. Sci. Rep 4, 5887; DOI:10.1038/srep05887 (2014).

no2 spain


Averaged tropospheric NO2 vertical column density for 1996 (left) and 2011 (right)