Basic Physical Aspects of Environmental UV Radiation

Abstract

Actinic effects describe photochemical, photobiological and photomedical reactions. They are dependent on: irradiance E produced by the source on a given plane, spectral power distribution, relative spectral responsivity (action spectrum) of the effect and exposure time.

As the reaction of a receiver depends mainly on the number of absorbed photons per area, the law of Bunsen and Roscoe due to radiant exposure H can be used. The effective (actinic) quantities can be defined by means of the spectral power distribution and the spectral responsivity. In all these cases however the additivity law must be valid (van Krefeld law). This means that at the same time there should not exist conductive i.e. catalytic or antagonistic effects.

The effective radiation quantities can be measured according to two methods: the spectral and the integral method. Main parameters of measurement equipments are given and a comparison with the effect on man of solar radiation with different quality is described.