Monitoring of aerosols
Nephelometer.
Photo: DERM
Aerosol monitoring is usually conducted to determine the amount of visibility loss due to fine particles in the air.
Monitoring is achieved by light scattering measurements in an instrument known as a nephelometer (shown right) which essentially comprises a light source, sample tube and light detector. A schematic of the operation is shown below.
Note that the illuminating beam spreads over a very wide angle, providing an integration of scattering coefficients over that angle; also that the detector is situated to measure light at right angles to the axis of that beam and to avoid any direct (un-scattered) incident light.
Last updated: 28 November 2003