Advancing Sub-10 nm Particle Measurements: ACTRIS NAIS Intercomparison Workshops in Helsinki

The 2nd and 3rd ACTRIS intercomparison workshop for Neutral cluster and Air Ion Spectrometers (NAIS) was organized in Helsinki in November 2024 and April 2025.

These workshops are an activity of the Cluster Calibration Center (CCC), which is a unit under the ACTRIS Center for Aerosol In-Situ Measurements (ACTRIS CAIS-ECAC) hosted by University of Helsinki. The aim of the unit is to standardize the measurements of sub-10 nm aerosol particles and develop their calibration methods and practices. In the workshops there were in total 5 instruments attending from ACTRIS National Facilities and 3 from other research institutes (outside of ACTRIS). Similar workshops will be organized regularly also in future.

Upcoming CCC workshops in 2025/2026:

• 3-10.11.2025: Calibration and intercomparison workshop for Particle Size Magnifiers (PSM)
• Spring 2026: Calibration and intercomparison workshop for nano particle size spectrometers (nano-MPSS, optimized <10nm) 
• Fall 2026: Calibration and intercomparison workshop for ion spectrometers (NAIS)

In the image on the left, ACTRIS CCC intercomparison setup (Photo by: Janne Lampilahti). 

For further information, contact us: actris-ccc@helsinki.fi