Tørseth received his Dr Scient degree at NTNU-Trondheim, and has worked at NILU since 1992.Since 1999 he has served as department head/research director.
His expertize includes measurements and data management and assessment of precipitation chemistry, reactive gases, aerosols and climate forcers, and their associated effects on ecosystems, health and climate.
He is engaged in a wide range of programs addressing assessments of air pollution on regional and global scales, including EMEP (head the EMEP Chemical Coordinating Centre), WMO Global Atmosphere Watch (GAW Country contact of Norway, member to the Scientific Advisory Group on Reactive Gases, responsible for the two GAW World Data Centers on Aerosols (GAW-WDCA) and Reactive Gases (GAW-WDCRG). He is also engaged in several research infrastructure activities like ICOS, ACTRIS and SIOS. He has a broad experience from many international research and capacity building projects.