The PMx Optical Monitor is a spectrometer used for the simultaneous and real-time measurement of concentrations of PM10, PM2.5 and PM1 (i.e., particles of smaller diameter at 10 µm, 2.5 µm and 1 µm respectively), at the same time, it is also able to provide the concentration and particle size distribution in 31 size classes (0.25-32 mm) with the simultaneous determination of the mass of particulate matter.

This tool is based on the method of counting the number of particles using their optical properties and the physical principle of measurement consists in the scattering of light in orthogonal direction. In particular, the air sample enters a measurement chamber where the particles are illuminated by a laser (λ = 655 nm) at 90 degrees to the direction of the flow. The light scattered by each particle is then sent through a mirror a a photodiode (detector). The intensity of the reflected light beam is proportional to the particle size. The number of counts per time unit depends on the number of particles and the volumetric flow rate. Pulse counts are transferred to a mass distribution, from which different PM values ​​can be obtained and with appropriate software you can get the mass of PM10, PM2.5 and PM1.

Not mandatory for ACTRIS.