It can be assessed by comparing the output of the light within each of the eight bands of the spectrum with a theoretically perfect source. The index is often identified as Ra8 to indicate the system of assessment used. Effects Light pollution is a very general term which refers to the effect of over-lighting resulting from poorly designed lighting schemes and excessive levels of light. It is commonly subdivided into sky glow, glare and light trespass, each of which has a different meaning technically, and is measured in different ways. The orange sky glow from an urban illuminates the night sky for miles around.
Glare is the uncomfortable brightness of a light source when viewed against a darker background.
However, because this is difficult to measure, the threshold increment , that is the percentage increase in luminance is sometimes used as a surrogate measure. Excessive glare from a floodlight illuminating a village garage in the Peak District. Light trespass is the spill of light beyond the boundary of the property on which a light is located. Light-spill from a security light at a commercial premises illuminates nearby trees. 2.3 Lighting Equipment Types 2.3.1 Lamps Incandescent filament lamps are those that produce their light by heating up a filament, usually tungsten, until it glows white hot.