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Levels of background tropospheric NO2 and O3 measured by TROPOMI-ESA (Veefkind et al. 2012) in the Iberian Peninsula. Top panels: NO2 tropospheric column measured on a April 2018, b April 2019, c April 2020 (during the strictest lockdown). Bottom panels: O3 tropospheric column measured on d April 2019, e April 2020 (during the strictest lockdown)
