The performance of the handheld Partector Pro has been evaluated against a reference mobility particle size spectrometer (MPSS) for 70 days at an urban background site. The number concentrations measured with the Partector Pro were in excellent and the number size distributions in reasonable agreement with the MPSS. The Partector Pro is thus a promising candidate for the widespread measurement of ultrafine particle concentrations as, for example, requested by WHO, at reasonable costs.

We present a novel version of an aerosol number size distribution instrument, showcasing its capability to measure particle number concentration and particle number size distribution between 1 and 12 nm. Our results show that the instrument agrees well with existing instrumentation and allows for both the accurate measurement of the smallest particles and overlap with more conventional aerosol number size distribution instruments.

Differential mobility analyzers (DMAs) are widely used to measure aerosol size distributions. Here we argue that DMAs operating steadily at unusually high flow rates are not as complex as they appear and could be used with considerable advantage in many measurements currently carried out in conventional DMAs. We hope that the considerations presented will encourage DMA manufacturers to develop high-flow DMAs far more versatile yet comparable in complexity to today’s mainstream instruments.

We analyze the mechanism whereby sunlight and iron catalyze the production of chlorine from chloride in sea spray aerosol. This process occurs naturally over the North Atlantic and is the single most important source of chlorine. We investigate the mechanism using quantum chemistry, laboratory experiments, and aqueous chemistry modelling. The process will change depending on competing ions, light distribution, acidity, and chloride concentration.

Atmospheric new particle formation (NPF), together with secondary production of particulate matter in the atmosphere, dominates aerosol particle number concentrations and submicron particle mass loads in many environments globally. In this opinion paper, we describe the paradigm shift to understand NPF in a continuous way instead of using traditional binary event–non-event analysis.