an air flow system comprising an air sampling system to deliver an aligned stream of particles to and through a detection system comprising an optical system and a detection chamber;

wherein said air sampling system comprises a nozzle having a terminal connected to said detection chamber, wherein through said nozzle a string of said particles is delivered to said detection chamber;

wherein said optical system comprises a triggering subsystem, a size subsystem and a fluorescence subsystem that interacts with said detection chamber transferring light toward said particle delivered from said nozzle in the direction of a first focal plane and a second focal plane;

wherein said triggering system and said size subsystem comprises first and second parallel trigger lasers each emitting beam of the same wavelength that is focused to said first focal plane and second focal plane respectively such that when the string of particles flows passed in one of the said beams, scattering of the light takes place and

avalanche photo detectors sensitive to the light scattered by the passing of particles in front of said triggered laser beams having the same wavelength;

wherein said fluorescence subsystem comprises a probe pulse femtosecond laser which emits a pulse of light inducing multiphoton radiation having a predetermined diameter centered on a particle detection volume to induce fluorescence, wherein said pulse femtosecond laser beam is triggered by a logically ANDed output signals of said wavelength selective avalanche photo detectors obtained from said emitted pulse of light substantially at said first focal plane and

a spectrophotometer sensitive to the emission of fluorescence emitted by said particles located in front of the femtosecond laser at the opposite side of said detection chamber;

a computerized electrical system connected to the nozzle, the avalanche photodetector and the spectrophotometer wherein said computerized electrical system integrates several electronic components of said air flow system to function in an autonomous way.