Typical MPSS measurements rely on bipolar diffusion charging, where the steady-state particle charge distribution depends on charger ion properties. By simultaneously measuring ion properties and particle charge fractions, we show that Hoppel&Frick theory accurately describes charging of sub-20 nm particles. By introducing siloxanes via outgassing from conductive silicone tubing, we further show that ion properties, and thus particle charge distributions, are sensitive to trace-gas composition.

Only a small fraction of airborne particles acts as seeds for cloud droplets and influence climate, yet the processes controlling their abundance remain unclear. Field measurements in Cyprus reveal that particles smaller than 20 nanometers can rapidly shrink. This shrinkage was linked to dilution and possible evaporation of organic compounds, identifying a previously overlooked nanoparticle sink that may reduce cloud-forming particles and weaken aerosol-driven cooling.

Low-cost air pollution sensors could greatly expand monitoring, but their readings are often affected by environmental conditions. We studied how to improve their accuracy by comparing them with high-quality instruments and using machine learning methods to correct the data. We found that reliable results can be achieved while reducing the time needed for calibration from about 70 % to 80 % of measurements to about 22 % percent, lowering costs while maintaining data quality.

We evaluate the ability of the Vaisala AQT530 (Air Quality Transmitter) monitors, comprising of low-cost sensors, to detect spatial and temporal differences. Collocated with reference instruments over 19 months in Nicosia, results showed that CO and PM (particulate matter) sensors captured daily, hourly, and monthly spatial trends. NO₂, NO, and O₃ sensors were less reliable due to environmental effects. Still, all sensors tracked monthly temporal variations at the same location, with PM_2.5 showing the strongest agreement with reference data.

Accurate measurement of nanoparticles is crucial for understanding their impact on new particle formation and climate change. In this study, we calibrated the Particle Size Magnifier version 2.0 (PSM 2.0), using both laboratory-generated and atmospheric particles. Some differences were observed in the calibration results, with direct calibration using atmospheric particles enhancing measurement accuracy.