Kees is an environmental exposure scientist and assistant professor at the Institute for Risk Assessment Sciences (IRAS) at Utrecht University.

His scientific research focuses on spatial modelling and exposure assessment for studies on environment and health. His recent focus involves cutting edge fine resolution spatio-temporal modelling to derive refined exposures using satellite and ancillary data. He has been involved in a number of large projects (BioSHARE, ESCAPE, ELAPSE) where he co-led the air pollution exposure assessment, and currently is a co-PI of the European research project EXPANSE, the NWO Gravitation programme Exposome-NL, the Utrecht Exposome Hub and PI of MOBI-AIR studies.