<div class="htmlview paragraph">Limited and nonlimited emissions of scooters were analysed during several annual research programs of the Swiss Agency of Environment Forests and Landscape (SAEFL, BUWAL)<span class="xref">*⁾</span>.</div> <div class="htmlview paragraph">Small scooters, which are very much used in the congested centers of several cities are a remarkable source of air pollution. Therefore every effort to reduce the emissions is an important contribution to improve the air quality in urban centers.</div> <div class="htmlview paragraph">In the present work detailed investigations of particle emissions of different 2-stroke scooters with direct injection and with carburetor were performed.</div> <div class="htmlview paragraph">The nanoparticulate emissions with different lube oils and fuels were measured by means of SMPS, (CPC) and NanoMet <span class="xref">*⁾</span>. Also the particle mass emission (PM) was measured with the same method as for Diesel engines.</div> <div class="htmlview paragraph">Extensive analyses of PM-residuum for PAH &amp; SOF/INSOF, as well as for VOC were carried out in an international project network.</div> <div class="htmlview paragraph">It can be stated, that the oil and fuel quality have a considerable influence on the particle emissions, which are mainly oil condensates.</div> <div class="htmlview paragraph">The engine technology influences the (nano)particle emissions by: mixture preparation, mixture tuning, oil consumption, postoxidation, quality, condition and temperature of the catalyst.</div> <div class="htmlview paragraph">Since the particulate emission of the 2-S consists mainly of lube oil condensates the minimization of oil consumption stays always an important goal.</div> <div class="htmlview paragraph">The amount of total PAH, as well as the toxicity equivalence factor TEQ correlate roughly with the total particle mass PM.</div>