Abstract - The thesis presents the results of studies of aerosol particle formation using ion and electron beam analytical techniques. The sources of aerosol particle formation studied are the following: 1.production of primary aerosol particles in the high Arctic region during summers 2.emission of ultrafine aerosol particles from wear on the road-tire interface 3.emission of aerosol particles from district heating units operating on three commonly used biofuels. A source of primary and nearly hydrophobic aerosol particles within the Arctic pack ice region during summers with a composition similar to that of average crustal rock was identified. Wear on the road-tire interface was found to generate numerous ultrafine aerosol particles of varying morphology. The particle number emission factors per vehicle and kilometer driven are similar in magnitude to the tail-pipe exhaust emissions obtained by use of modern engine technology. Particle emissions from the combustion of biomass were characterized in terms of their elemental composition and particle formation mechanisms.