Hi Sukhbir Singh, it sounds like what you are looking for is know as a " Particle Counter" there are a huge number available out there.. just google search. They mainly use optical scattering to count an measure the size of particles drawn in to the instrument. They can be lab based or hand held. Note that they do have a minimum size cut off so are not really applicable for nanoparticles, but they should be ideal for your application.

Hi Sukhbir Singh, it sounds like what you are looking for is know as a " Particle Counter" there are a huge number available out there.. just google search. They mainly use optical scattering to count an measure the size of particles drawn in to the instrument. They can be lab based or hand held. Note that they do have a minimum size cut off so are not really applicable for nanoparticles, but they should be ideal for your application.

Thanks a lot. It measure the dust particle size .

As noted above, light scattering instruments are available for particulate measurement - some simply measure the light attenuation of a particle filled atmosphere - the higher the particle concentration the lower the level of transmitted light. However, if the range of particulate sizes is important besides particulate concentration, then it is less straightforward. Usually particulate size, especially at very small diameters, requires something like fluctuation spectroscopy (Photo Correlation Spectroscopy) to determine particulate size and this would ordinarily require the air-stream to pass through a water sample cell to allow the measurement to proceed. Failing this, filter entrapment of the particles in the air and subsequent optical examination would give a good indication of the particulate geometry and diameters.