Condensable primary organic aerosols are a class of compounds that are vapour phase at stack conditions, but which can undergo both condensation and evaporation as the stack air is cooled and diluted upon discharge into ambient air. In the current emission reporting to the Air Convention, some countries include, and some exclude such emissions in their inventories.

In this study, new residential combustion emission estimates have been developed for the years 2005-2019, with improved and consistent estimation of condensable emissions. A series of modelling runs has shown that condensables can have significant effects on air quality, trends, and source-receptor relationships, but many scientific issues remain concerning their characteristics. However, these new emissions provide the best available basis for future improvements in both the emission inventories and model formulations.