The size distribution of the PM10 fraction is obtained by means of the APS Model 3321, which provides real-time aerodynamic measurements of particles from 0.5 to 20 µm binned into 52 channels, addressing predominantly the coarse fraction of the particulate.

The Aerodynamic Particle Size (APS) Model 3321 is based on the time-of-flight particle sizing, in which the aerodynamic size of a particle determines its rate of acceleration, with larger particles accelerating more slowly due to increased inertia; the time of flight between two laser beams is recorded and converted to aerodynamic diameter using a calibration curve. The instrument is also able to measure in parallel the light scattering intensity of the sized particles in the equivalent optical size range of 0.37 to 20 µm, thus providing further insights into the aerosol nature and composition.

During the measurement campaign carried out from 16 August 2022 to 04 September 2022, the instrument was active from 16 to 19 August 2022 and the first data collected are shown below: