Atmospheric Molecular Processes Group

Laboratory studies on the formation, growth and ageing of aerosols and their effects on human health and climate Aerosols are emitted into the atmosphere but can also be formed in situ, from the oxidation of gaseous precursors, leading to secondary aerosols. They play an important role in the climate system and have a detrimental effect on human health, particularly in urban areas. The main research tool of the molecular cluster and particle processes group is a 27 m³ indoor smog chamber which is equipped with a large suite of state of the art instrumentation. This facility is linked to the European network of smog chambers (EUROCHAMP) and is operated as a user laboratory.

The molecular cluster and particle processes group is also a member of the Cosmics Leaving OUtdoor Droplets (CLOUD) project based at the European Organization for Nuclear Research CERN. This collaboration, involving more than 20 research groups worldwide, has vastly improved the current understanding of atmospheric new particle formation, and the chemistry governing it. The experiments are conducted in an ultra-clean electro-polished stainless steel tank, where the chemical reactants and the physical conditions can be far more precisely controlled than in other facilities. The main topics so far investigated by CLOUD include the role of sulfuric acid in particle nucleation, the formation of particles from biogenic emissions (gases emitted by vegetation) and the chemistry leading to the formation of particles in urban environments.

Based on these laboratory studies we aim to:

• understand new particle formation from anthropogenic and natural precursor gases
• understand the mechanism of growth of secondary aerosols
• characterize the chemical composition of primary and secondary aerosols
• understand the processing and ultimate fate of aerosols in the atmosphere
• understand the relation between aerosol chemical composition and their health effects

The results of our research are published in peer-reviewed scientific journals. The greater understanding of aerosol formation resulting from our work can provide policy makers as well as other stake holders with the necessary information to make decisions which lead to improved urban air quality and a reduced human impact on the environment.