ABSTRACT
The integrating nephelometer (1,2,3) measures the optical scattering coefficient (σ s) from the light scattered by particles (σ sp) and gases (σ sg) in a sample volume integrated over essentially all scattering angles (hence the name) over a weighted range of visible wavelengths (4). For a given particle shape (5), size distribution (6), and chemical composition (7), this scattering extinction coefficient is proportional to the mass concentration of suspended particles in the sample volume and the scattering due to atmospheric gases. The gaseous or “Rayleigh” scattering is a function of atmospheric temperature and pressure and can be accurately calculated to determine the fraction of the integrated scattering due to suspended particulate matter (8).
