The project AHMA funded by Jane and Aatos Erkko’s Foundation, aims to understand the particle emissions from light-duty road vehicles operating in a Finnish environment, e.g. in the wide range of outdoor temperatures. The work includes statistical analysis of data obtained before from measuring the emissions of hundreds of individual vehicles, detailed investigations of emissions related to their wintertime use and expanding the understanding on the exhaust-related secondary aerosol formation in different research environments. In addition, we conduct groundbreaking studies to quantify, how large emissions sources fuel-operated auxiliary heaters of vehicles are. AHMA Partners include Tampere University (Aerosol Physics Laboratory) and University of Eastern Finland (Aerosol Physics Group).