His primary areas of study are Aerosol, Atmospheric sciences, Nucleation, Taiga and Particle number. Pasi Aalto performs integrative Aerosol and Vapours research in his work. His Atmospheric sciences study integrates concerns from other disciplines, such as Ultrafine particle, Relative humidity and Forest ecology.
His study in Nucleation is interdisciplinary in nature, drawing from both Nitrogen dioxide and Analytical chemistry. His work deals with themes such as Atmosphere, Meteorology and Particle growth, which intersect with Taiga. His studies in Particle number integrate themes in fields like Inorganic chemistry, Spectrometer, Standard algorithms and Data set.