SUREAL-23 program work package schedule. The SUREAL-23 project is developing novel nanoparticle concentration/size/composition measurement instrumentation, with special focus on the ultrafine nanoparticles emitted by internal combustion engines. The goal of the project is to quantitatively and qualitatively assess nanoparticle emissions of less than 23 nm and down to 1nm in size, in order to facilitate future emission regulations as well as to assess any potential trade-offs between advances in engine technology, efficiency and emissions.