Visibility is defined as the distance at which an observer can distinguish an object from the background. Visibility can be impaired by anything present in the air that reduces the amount of light reaching the observer, by scattering or absorbing it.

Common visibility deterioration is due to high particles concentration or high humidity. Particles can be of natural or anthropogenic origin, for example, from car emission, wood burning, sandstorms or smog.

Typical applications for visibility monitoring include:
Tunnels, roads and transport
Haze and bushfires
Aviation
Fog detection

Ecotech offers the following products for opacity measurement, aerosol light scattering and particulate monitoring instrumentation, which forms part of an air or dust quality management system: