Particles in the atmosphere cause millions of premature deaths globally, influencing climate change and the environment. Transportation is a major source of organic particles and while the emissions of the particles are regulated, the secondary organic particles formed in the atmosphere from the oxidation of gaseous organic material are not taken into account. The released aerosol also goes through additional transformation processes in the atmosphere, changing as it evolves.
In his thesis, Oskari Kangasniemi used computational methods to study how transportation related aerosols evolve in the atmosphere.
“Volatility can have a big impact on how the aerosol develops. The smallest particles are often assumed to collide with bigger particles and stick to them, but they can actually grow to be larger particles and stay in the aerosol population. Unfortunately, there can be a huge number of different organic species in an emission with unknown volatilities making it challenging to simulate the effect of volatility,” says Kangasniemi.
Although there are methods to simplify the problem, the issue of unknown volatility properties remains. In his thesis, Kangasniemi used computational methods to address this issue. Evaporation simulations and optimisation methods can be used alongside experimental data to obtain information on the volatility of emissions.
For example, emissions from ship engines contain large amounts of organic matter, which can occur in both particulate matter and gases These compounds can easily oxidise in the atmosphere and form secondary organic matter. Dilution of the emission also significantly affects organic matter, especially within this volatility range, and can therefore alter the emission in the atmosphere considerably.
“In addition, most instruments used for measuring emission require the sample to be diluted. This can be a significant source of error if the effects of volatility are not considered,” Kangasniemi adds.
Oskari Kangasniemi is from Pälkäne and works in the Aerosol Physics Laboratory at Tampere University.
Public defence on Friday 28 November
The doctoral dissertation of MSc (Tech) Oskari Kangasniemi in the field of aerosol physics titled Simulating Volatility and Atmospheric Evolution of Transport Related Emission will be publicly examined at the Faculty of Engineering and Natural Sciences at Tampere University 12 o’clock on Friday 28 November 2025 at the Hervanta campus, in the auditorium TB109 of the Tietotalo Building (Korkeakoulunkatu 1, Tampere).
The Opponent will be Docent Ari Karppinen, Finnish Meteorological Institute. The Custos will be Professor Miikka Dal Maso, Tampere University.