Emission Training Services develops automotive training material covering exhaust emissions, combustion engine technology and fuels. It also offers lectures, training courses and technical research and consultancy services. Gerrit Kadijk (1963) is an automotive emission engineer and owner of ETS. Since 1988 he has been working as a researcher in the field of combustion engines, fuels and exhaust gas after-treatment systems. From 2012 to 2020 he was responsible for the development of the particulate filter check. In 2021 he published the book 'Roet in beeld' (Dutch) and in 2022 'Particles Matter'. Emission Training Services owns the websites www.deeltjestest.nl and www.particlesmatter.com