The oxidative potential (OP) of air pollution particles might be a metric explaining particle toxicity. This study quantifies OP of particles of fresh and aged car and wood burning emissions and how OP changes over time, using novel high time resolution instruments. We show that emissions from wood burning are more toxic than car exhaust per particle mass, especially as they age in the atmosphere. We also calculate emission factors for OP, which could help to improve air pollution policies.

We developed a new method to measure how particles absorb light as they change in size, which is critical for understanding their climate impact. Our approach uses a sensitive instrument that measures light absorption directly from particles in real time. By pairing this with a device that sorts particles by size, we achieved accurate, size-resolved measurements. Our findings closely match theoretical models, offering a promising tool for future research into how particles influence climate.

We present a new photoacoustic instrument for simultaneous measurement of aerosol light absorption at multiple wavelengths. High performance is reached by using an optically-read cantilever microphone, which allows for highly sensitive absorption measurements at a compact size. Performance in field conditions is demonstrated with black carbon monitoring at an air quality measurement station, where our results agree well with reference instruments deployed at the site.

Insoluble aerosol particles such as minerals and black carbon can trigger freezing inside clouds, which leads to rain formation. However, both particle types are relatively poor nuclei for cloud droplets. In this work, theoretical calculations are presented about the ability of surface tension reducing compounds to promote cloud drop formation around insoluble aerosols. The calculations indicate that such surfactants can be efficient in "smuggling" insoluble particles into cloud droplets.

We investigated the space charge influence on the aerosol neutralization principle used in all aerosol measurement instruments. We found that the space charge cause ions to separate unevenly, leading to different rates of neutralization in different parts of the inlet, impacting the effectiveness of the neutralization process.

Our study explores particles in Arctic soils and streams that influence ice formation in clouds. By analysing these environments, we identified specific microorganisms producing these particles. This research, which measured these particles in Arctic streams for the first time, provides new insights into their ecological role and transfer from soil to water. Our findings help us understand their production, sources, and potential impact on climate.

The COVID-19 lockdown measures in 2020 reduced emissions of various substances improving air quality. However, PM2.5 stayed unchanged due to NH₃ and related chemical transformations. Higher humidity favoured more SO₄^2- production so as accumulated NH₃ did. Excess NH₃ neutralised HNO₃ towards NO₃^-. In high NH₃ conditions such as those in 2020, a small reduction of NO_x levels drives faster oxidation toward NO₃^- and slower deposition of total inorganic NO₃^- causing high secondary PM2.5.

Dust deposition flux was investigated in lutruwita/Tasmania, Australia, between 2016 and 2021. Results show that the use of direct measurement of aluminium, iron, thorium and titanium in aerosols to estimate average dust deposition fluxes limits biases associated with using single elements. Observations of dust deposition fluxes in the Southern Hemisphere are critical to validate model outputs and better understand the seasonal and interannual impacts of dust deposition on biogeochemical cycles.

We evaluated the performance of four cascade impactors for collecting and analyzing organic markers in airborne UFP under laboratory and field conditions. The cut-off was influenced by both impactor design and aerosol mixture. Two key factors caused variations in mass concentrations: evaporation of semi-volatile compounds and bounce of larger particles and fragments. Our findings highlight the complexities of accurately separating and analyzing organic marker mass concentrations in airborne UFP.

This study shows that electrostatic dispersion can influence time-evolution of the charge and size distributions of radioactive and nonradioactive particles in the atmosphere. Three approaches with different levels of complexity are proposed to couple electrostatic dispersion with microphysical and radiological processes. These approaches can be useful to better understand the behavior of particles in atmospheric systems with radiation sources.