DownToTen is developing a robust methodology that will enhance the regulatory approach towards particle number (PN) emissions in the sub 23nm region. The focus is on the new generations of direct injection gasoline and diesel engines under real world conditions. 

Based on detailed investigations of the nature and characteristics of these particles, DownToTen is evaluating a variety of sub 23 nm PN measurement instruments and sampling approaches, using rigorous criteria under conditions of challenging aerosol from a variety of sources. The objective is a PN-PEMS demonstrator with high efficiency in determining PN emissions of current and future engine technologies in the real world. 

DownToTen also aims to assess the fraction of particles left out of control and assist the better understanding of exhaust particle impacts on air pollution. It also complements the in-cylinder particle formation and particle filtration research with simulation along the exhaust pipe and in the sampling system.