Assessment of the exposure to biologically effective UV radiation using a dosimetric technique to evaluate the solar spectrum

Abstract

A cost effective method employing polysulphone, nalidixic acid, 8-methoxypsoralen and phenothiazine as UV dosimeters is presented for evaluating the UV spectrum. The exposure measured by each dosimeter is a function of the source spectrum and the spectral response of the material. Each material has a different spectral response and records a different dose for the same exposure. A least squares method is employed to extract the source spectrum from the four dose measurements. A number of spectra have been evaluated and the differences between these spectra and the associated irradiances compared to the spectra and irradiances measured with a calibrated spectroradiometer is less than 20%. The technique allows simultaneous multi-site measurement at positions that may be inaccessible to sensitive and expensive equipment. The technique was employed to evaluate the spectrum on the chest and shoulder of four subjects. The erythemal exposures were derived from the evaluated spectra with the chest exposures 0.7 to 0.8 those of the shoulder exposures.

An estimation of biological hazards due to solar radiation

“…The development and testing of the method has been previously described [16,13,14]. The dosimeter materials employed in the spectrum evaluator are polysulphone, nalidixic acid (NDA), 8-methoxypsoralen (8MOP) and phenothiazine [13].…”

“…Previous research has measured a difference of approximately up to 20% between spectra evaluated with the system and a calibrated spectroradiometer [13].…”

“…Briefly, for each type of dosimeter film exposed to a source spectrum S(λ) over a time interval, T, the change in optical absorbance, ΔA i at a set wavelength is given by [13]:…”

“…The spectral responses give the effectiveness of each wavelength for the production of a change in the optical absorbance of each film. For each material, it is defined as the change in optical absorbance at a set wavelength for each film due to unit irradiance in the wavelength interval λ to λ + dλ [13]. Polysulphone exhibits a high response at UVB wavelengths with a rapid drop for wavelengths longer than 320 nm.…”

“…A detector [13] based on four different dosimeter materials was previously developed for estimating the solar UV spectrum and will be employed in this paper for evaluation of the hazard of the UVA waveband.…”