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 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.

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 examines new particle formation (NPF) in the Bolivian Andes at Chacaltaya mountain (CHC) and the urban El Alto-La Paz area (EAC). Days are clustered into four categories based on NPF intensity. Differences in particle size, precursor gases, and pollution levels are found. High NPF intensities increased Aitken mode particle concentrations at both sites, while volcanic influence selectively diminished NPF intensity at CHC but not EAC. This study highlights NPF dynamics in the Andes.

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.