New particles form in the atmosphere and can influence the climate. We studied Arctic new particle formation (NPF) from 2022 to 2024 at the Zeppelin Observatory, on Svalbard. NPF occurs from April to November, peaking in late spring as sunlight increases. Some particles measured on-site grow large enough to seed clouds. Sunlight and existing aerosol particles strongly impact the likelihood of NPF, which mainly originates from marine regions, particularly the Greenland Sea.

Aerosols, a large uncertainty in climate modeling, can be formed when gas vapors and particles begin sticking together. Traditionally, these particles are assumed to behave like hard spheres that only stick together upon head on collisions. In reality, particles can attract each other over distances, leading to more frequent sticking events. We found that traditional models significantly undercount these events, with real sticking rates being up to 2.4 times higher.

This study evaluates the performance of energy-dispersive X-ray fluorescence (ED-XRF) on particulate matter (PM₁₀) samples collected on quartz and Teflon filters through an inter-laboratory comparison. Detection limits were higher on quartz, but measurement repeatability was similar. Strong elemental correlations suggest that, with proper corrections, quartz filters can provide reliable results. These findings support their feasibility for ED-XRF analysis.

The concept of mean free path is fundamentally important to aerosol studies. Recent studies suggested that the mean free path of air (λ_air) could have been significantly overestimated by a factor of ~2. Here we show that this potential overestimation does not directly affect collisions-induced aerosol dynamics in atmospheric conditions without a high excess latent heat, because the collision rate is determined by the effective mean free path for vapor and particle collisions rather than λ_air.

Aerodyne aerosol mass spectrometer (AMS) is widely used to quantitatively measure the chemical compositions of aerosols in the atmosphere. This work presents a comprehensive analysis of the newly developed aircraft inlet system for AMS and tools for aerosol beam diagnostics to minimize particle losses. When the particle beam is properly monitored and aligned, the new inlet system can be operated at higher altitudes while sampling a wider size range of particles than previous versions.

New particle formation (NPF) is a process of forming new aerosol particles in the atmosphere. It was widely studied in boreal forest areas in Finland and Estonia; but its features and precursors in Siberian boreal forest remained unclear. We did a comprehensive analysis using data from state-of-art instruments and implement both traditional and new methods of data analysis. Understanding these processes helps us grasp how Siberia’s atmosphere evolves and contributes to global climate dynamics.

Particle formation rate is one of the key factors to study the physical properties of aerosols, because it is still not entirely clear how particles form under different environmental conditions. By developing powerful and simple particle formation rate models, we can predict how many atmospheric particles are produced, and compare it with the real-time measurement to help with the scientists on discovering more hidden particle formation mechanisms.

Metal nanoparticles (Au, Pt, Cu and Ni) were generated in the aerosol phase using spark ablation and analysed for size, shape and number concentration. Particles as small as 1 nm and up to > 60 nm show shapes from fully spherical to fractal-like as characterized by electron microscopy. Furthermore, the metal particles were mixed with TiO₂ nanoparticles and the number and size of metal particles coating the TiO₂ were determined.

We present continuous ice-nucleating particle data that were measured in the Alaskan Arctic from Oct. 2021 to Dec. 2023. We found a greater efficiency in the arctic immersion freezing during autumn compared to those found previously at two mid-latitude sites, as well as profound freezing efficiencies in spring, presumably due to arctic haze events. Our study will be useful to improve atmospheric models to simulate cloud feedback and determine their impact on the global radiative energy budget.

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.

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.

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 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.

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.

Black Carbon (BC) is a pollutant from combustion that affects the climate and is harmful to health. We tested four different small BC sensors with a reference in Helsinki. The sensors compared well with the reference. As a sensor network they were able to capture differences in BC. Changes in temperature (T) and relative humidity (RH) caused error in the measurement. To reduce the effects of T and RH on BC sensors, more robust boxes should be developed or corrections should be applied.

Although spray flame synthesis (SFS) is a promising approach to prepare nano materials with tailored properties, the impurity formation is not fully understood in SFS. To contribute to this topic, maghemite nanoparticles were prepared by SFS, and two complementary experimental approaches were used to investigate the evolution of soot and carbonaceous surface adsorbates. The methodological procedure and the data provided can be used to denote/compare SFS-materials more reliably in the future.

Several papers have reported on electrospray technique and they have shown that uniform thin films with different surface morphologies can be deposited. Nonetheless, the studies do not give a systematic way of designing different surface morphologies and most outcomes are based on a trial-and-error method. Therefore, in this study a systematic way of designing thin films of different surface morphologies using electrospray technique has been developed.