Since 2018, the mathematician Björn Hansen has been head of the European Chemicals Agency ECHA. After working as a scientist in Göttingen, Germany, and Eindhoven, the Netherlands, he joined the European Commission in 1991as Head of the Chemicals Unit of the Directorate-General Environment in Belgium, among other responsibilities. Hansen was involved in the development of the European Chemicals Regulation REACH from its inception. REACH stands for “Registration, Evaluation, Authorization and Restriction of Chemicals”. The REACH regulation has been in force since 2007 and Hansen’s international involvement includes leading a number of multilateral contact groups at three UN climate conferences.