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Centre for Atmospheric Science


Composition and reactivity of organic aerosols

Approximately 30-50% of atmospheric aerosol particles are composed of organic material. Usually, these organic aerosol particles are formed within the atmosphere from gaseous organic precursors. 

Despite their dominance, the chemical composition, formation pathways, and atmospheric reactions and effects of these organic particles are poorly understood. This is mainly due to their incredibly complex composition - there are more than 10,000 organic compounds present in organic aerosol, covering a wide physical-chemical parameter space. 

The analysis of these highly complex mixtures at trace level concentrations is a main challenge in the study of atmospheric aerosols. To better characterise aerosol effects on climate and human health an improved understanding of aerosol composition, evolution and sources is needed, which is only possible through an improved knowledge of particle composition.

We are using a range of laboratory experimental techniques to study fundamental aspects of aerosols formation and composition and we are characterising aerosol and rain samples collected in the ambient atmosphere ranging from polluted urban to clean remote locations. Some of the research we have conducted in this area include:

  1. Detailed, molecular-level analysis of organic aerosol composition 
  2. Aerosol Extractive Electrospray Ionisation Mass Spectrometry (MS)
  3. Criegee Intermediates
  4. Particle reactivity and particle phase 


Reactive Oxygen Species (ROS) - a new aerosol toxicity metric and aerosol lung cell cultures studies

Epidemiological studies show consistently positive correlations between aerosol particle exposure and a range of adverse health effects. The World Health Organisation (WHO) even lists air pollution particles as the single most pressing public health issue - accounting for approximately 5% of all deaths worldwide.

Despite a large number of studies on atmospheric particle toxicity, the biological pathways causing the adverse health effects of particulate air pollution are poorly understood - there is no conclusive evidence as to which particle properties are causing their toxicity. Chemical particle components are likely a key factor, but are difficult to accurately define. Therefore, identifying health-relevant particle parameters, components and sources is crucial for improved and efficient air pollution mitigation strategies.

Atmospheric aerosol particles contain a range of oxidising aerosol components (i.e. Reactive Oxygen Species, ROS), which are potentially toxic as they can oxidise biological molecules at the liquid lung surface layer or generate oxidising components once deposited on the lung surface. From an analytical point of view it is highly challenging to quantify these oxidising particle components as some of them have short lifetimes requiring fast measurement techniques.

As part of our work into this area, our research includes:

  1. Reactive Oxygen Species (ROS)
  2. Peroxyacids synthesis
  3. Nanoparticle - lung cell culture online deposition chamber


Other research: 

The Kalberer Group also has a number of research activities and interests in other areas, these include:

  1. Analysis of organic tracers in ice cores
  2. Selective analysis of plant surfaces 
  3. MEMS-based aerosol mass detection


For more information on any of these projects, please refer to Professor Markus Kalberer's personal staff profile.

Centre Highlights

• January 2024: The CCPG have successfully submitted a proposal for PACESETTERS!

• September 2nd 2023: Dr Annela Anger-Kraavi has co-authored a paper analysing just transition narratives in European coal regions. Read the paper here

• December 13th 2022: The CCPG have co-authored a paper on game-changing innovations towards net-zero, published in Energy Strategy Reviews. Read the open access paper here.

• November 15th 2022: The final conference of PARIS REINFORCE is taking place today in Sorbonne. Read more about the event here

• October 24th 2022: The CCPG have successfully submitted a proposal for the Cambridge-Tsinghua joint research initiative! 

• May 5th 2022: We've submitted to the UNFCCC's Global Stocktake (GST). More information is available on our news page. 

• March 23rd 2022: Multiple CAS academics have published a paper investigating the future role of anthropogenic methane emissions. Read the open access paper here.

• Feb 18th 2022: Dr Parris and Dr Anger-Kraavi have co-authored a paper that develops a tool to support co-designed transformative change. Read the open access paper here.

• Dec 16th 2021: Dr Parris has co-authored a paper that introduces a tool to support plastic pollution policy. Read the open access paper here.

• Nov 22nd 2021: Dr Anger-Kraavi has co-authored a paper with Paris Reinforce. Read the open access version here

Want to know more about our high-profile publications? Check out our Publication Highlights!