According to current theories, nanometre-sized particles are not formed in polluted areas. Observations show that new particles are formed in large, comparatively polluted cities, such as Shanghai, Nanjing and Beijing.
A mechanism that reveals what molecules have a part in the formation of nanometre-sized ultrafine particles was discovered in a study conducted together with researchers from Fudan University, and published in Science.
"In practice, it takes sulphuric acid and dimethylamine. These atmospheric clusters grow molecule by molecule, and form new particles in polluted air as well," says Academician Markku Kulmala.
According to Professor Tuukka Petaja, atmospheric science researchers have throughout the years played a key role in the development of the measuring equipment and analysis methods that enabled getting these results. The measuring equipment, which enables new scientific break-throughs in the fields of air chemistry and aerosol physics, has been developed in cooperation with spin-off companies (Airmodus Oy, Particle Size Magnifier, PSM; Karsa Oy, Chemical Ion-ization Mass Spectrometer, CI-APiTOF), and the Estonian Airel Ltd (Neutral Cluster and Air Ion Spectrometer, NAIS), among others.
The Atmospheric Science at the University of Helsinki ranked 15th in the world in the Global Ranking of Academic Subjects by the international Shanghai Ranking http://www.