Born 1955 in The Hague. Study of natural sciences Leiden Univ. (1984), research associate at Geosens B.V. (1984-1987), research scientist at the Max Planck Institute for Chemistry (1987-1993), PhD in Physics and Astronomy Utrecht Univ. (1990), Professor of Atmospheric Physics and Chemistry Univ. of Wageningen and Utrecht (1993-2000), Director and Scientific Member at the Max Planck Institute for Chemistry (since 2000), Professor in Atmospheric Physics, University of Mainz.