Birmili, W; Sun, J; Weinhold, K; Merkel, M; Rasch, F; Spindler, G; Wiedensohler, A; Bastian, S; Loeschau, G; Schladitz, A; Quass, U; Kuhlbusch, TAJ; Kaminski, H; Cyrys, J; Pitz, M; Gu, J; Peters, A; Flentje, H; Meinhardt, F; Schwerin, A; Bath, O; Ries, L; Gerwig, H; Wirtz, K; Weber, S
The German Ultrafine Aerosol Network (GUAN) is a cooperative effort to scientifically explore the health and climate-related properties of the atmospheric aerosol in Germany. This work presents results on the basis of long-term observations of particle number size distributions and equivalent black carbon (eBC) between 2009 and 2014. At 17 observation sites, we found variations in mean total particle number concentration (diameter range 20 to 800 nm) between 850 and 10,500 p. cm(-3), and in eBC mass concentration between 0.17 and 2.8 mu g m(-3). Time series trend analyses yielded a significant relative decrease in eBC mass concentration (median: -5%/year) and in total particle number concentration (median: -4%/year), which is rather consistent at almost all sites over Germany. The consistent downward trends suggest that air quality-related societal efforts, which have been targeted mainly at reductions of total particle mass emissions, have a beneficial effect on ambient total particle number, ultrafine particle number, and eBC mass concentrations as well.