Transport Sectors’ Real-World Emissions: From Gaseous Precursors to Secondary Aerosol Formation in Urban Air

Abstract

Mobility is essential to our modern world to move people and goods. However, mobility has also its downside as transport sectors are substantial emitters of greenhouse gases and air pollutants. Increasingly energy efficient combustion engines and turbines, as well as electrification and carbon-neutral fuels, will reduce the climate impacts of transportation. When such technologies are combined with advanced exhaust after-treatment technologies, air pollution impacts will also be reduced. Many exhaust emissions are already regulated regionally or globally, while actions to prevent the formation of secondary aerosols from emitted gaseous precursors in the atmosphere are missing. To increase understanding on the role of transport sectors’ exhaust emissions on the secondary aerosol formation and to identify gaps in the knowledge, we present a summary of semi-volatile compounds, secondary air pollutants, ultrafine particle and particulate matter (PM2.5) emissions. Non-exhaust emissions are also considered. The results are based on the PAREMPI project’s emission database based on a literature review and new results from the projects’ ongoing research activities.