Economic crisis detected from space: Air quality observations over Athens/Greece

Using both satellite observations of tropospheric NO 2 columns and a number of economic metrics, we investigate the impact of the economic crisis (from 2008 onward) on air quality over Greece, and Athens in particular. The multiannual analysis shows that NO 2 columns over Athens have been significantly reduced in the range 30–40%. This decline is further supported by surface measurements of atmospheric NO 2 mixing ratios. Additionally, the declining local concentrations of NO, CO, and SO 2 are associated with an increase in ozone due to reduced titration by NO. In particular, regression analysis revealed that the reduction of NO 2 (0.3 ± 0.2 ppbv y −1 ) and SO 2 (0.2 ± 0.1 ppbv y −1 ) during the period 2000–2007, significantly accelerated during the economic crisis period (from 2008 onward), reaching 2.3 ± 0.2 ppbv y −1 and 0.7 ± 0.1 ppbv y −1 , respectively. The strong correlations between pollutant concentrations and economic indicators show that the economic recession has resulted in proportionally lower levels of pollutants in large parts of Greece.