This study examines the deliquescence behavior of NaCl particles in a turbulent humidity field using the wind tunnel LACIS-T. The results show turbulent relative humidity (RH) fluctuations affect the number of deliquesced particles, depending on mean RH, strength of humidity fluctuations, and particle residence time. It turns out that, in addition to the mean RH, it is essential to consider humidity fluctuations and particle history when determining the phase state of the deliquescent particles.

Acyl peroxy radicals can act as atmospheric oxidants of unsaturated hydrocarbons if their 1) unimolecular reactions are slow and 2) bimolecular accretion reactions are fast. Using theoretical tools, we show which acyl peroxy radicals should be considered as oxidants in the atmosphere.

We investigated the sources of ultrafine particles (UFPs) in Payerne, Switzerland, highlighting the significant role of secondary processes in elevating UFP concentrations to levels comparable to urban areas. As the first study in rural midland Switzerland to analyze new particle formation events and secondary contributions, it offers key insights for air quality regulation in Switzerland and central Europe.

Quantification of autoxidation chemistry is a complex task, essential to our understanding of atmospheric secondary aerosol formation and its impact on climate. In this work, we introduce the autoCONSTRAINT module, a semi-empirical method to deduce reaction rate coefficients for lumped autoxidation chemistry schemes based on experimental data. The theoretical approach is analytical and provides mathematically correct, though non-unique, solutions with low computational cost.

This study examines how sampling frequency influences the accuracy of low-cost particulate matter (PM) sensors. It finds that high sampling rates (15 seconds) are vital for detecting short pollution spikes like vehicle emissions, while lower rates (1 hour) are enough for tracking long-term trends. Conducted in real-world outdoor conditions, the research offers practical guidance to balance energy use and data accuracy, supporting scalable, cost-effective air quality monitoring solutions.

We report a substantial build-up of reactive molecules by sunlight in organic particulate matter causing adverse health effects. Metals naturally or by traffic emitted can complex with organic materials and initiate photochemical processes. At low humidity organic particles may become highly viscous, which lets the accumulate reactive species. We found that copper acts as an reducing species to remove some of the harmful species in the particles.

The study explores the formation of small soot clusters by precursor molecules at high temperature. Higher temperature speeds up the decomposition of gas molecules, accelerating the formation of cyclic structures decorated by aliphatic chains. This research offers new insights into the early steps of soot formation, which could help develop more informed kinetic models for pyrolysis and combustion processes.

Using quantum chemical methods we studied the uptake of first generation oxidation products onto freshly nucleated particles (FNPs). We find that pinic acid can condense on these small FNPs at realistic atmospheric conditions, thereby contributing to the early particle growth. The mechanism involves two pinic acid molecules interacting with each other, showing that direct organic-organic interactions during co-condensation onto the particle contributes to the growth.

Ensuring that all measuring instruments deliver reliable results is an important task. For aerosol measurement, a health-related parameter is not yet well defined worldwide. We have therefore developed a test bench to evaluate and compare instruments on this key parameter. Based on the success of an initial comparison with our instruments, we underline the feasibility of a standardized test and offer a framework for improving accuracy and consistency of aerosol size distribution assessments.

Aerosol formation is an important process for our global climate. However, there are large uncertainties associated with the formation of new aerosol particles. We present quantum chemical calculations of large atmospheric molecular cluster composed of sulfuric acid (SA), ammonia (AM) and dimethyl amine (DMA). We find that mixed SA-AM-DMA clusters more efficiently for freshly nucleated particles compared to the pure SA-AM and SA-DMA systems.

Aersols, are important in many parts of industries and research. To learn more about aerosols, especially when containing nanoparticles, the here presented Centrifugal Differential Mobility Anlayser (CDMA) allows to measure the mobility equivalent diameter and the Stokes equivalent diameter at the same time. The result is a two-dimensional property distribution that provides deeper information about the entire particle collective than the isolated measurement principles.

We studied how nanoparticles form in the atmosphere at two different altitudes in Cyprus, focusing on how meteorology impacts this process. Using data from two sites, we found that air from lower regions carries particles up to higher areas, affecting air quality and potentially climate. Our findings help improve understanding of how particles form and grow in the air, which is important for predicting changes in climate and air pollution in the future.

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 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.