The Merits of an Envelope Action Spectrum for Ultraviolet Radiation Exposure Criteria

Few generally accepted standards for personnel exposure to ultraviolet radiation presently exist. Values which have been used as guide-lines were based either on a single-wavelength effect (253.7 nm) which may be emitted from an essentially monochromatic source, or on data which is somewhat at variance with that obtained in more recent investigations. The Committee on Physical Agents of ACGIH has proposed a tentative TLV for ultraviolet which assumes that a single spectral-effects weighting curve can be made applicable for exposure to both the eyes and the skin. The advantages of this aproach are: (1) Calculations and measurements are simplified. (2) It favors the development of a single direct-readout hazard instrument. It also makes an assumption that the eye is the critical organ and that distinction between eye and skin exposure is not essential; that it is acceptable to apply a large factor of safety to the skin in order to protect the eyes. The biological data which support this synthesized approach, and the limitations of this type of standard, and other possible ultraviolet radiation standards are discussed.