Wavelet analysis of personal solar UVR exposure

Scaling properties of personal solar ultraviolet radiation exposure (pUVR) recordings are investigated using the Wavelet Transform (WT) spectral analysis. Personal UVR recordings are collected by UVR monitors designed to measure erythemal UVR. Sun exposure recordings of a school child, farmer, marathon runner and outdoor worker in South Africa are analyzed. A scaling behavior in all analyzed pUVR datasets is found. The scaling behavior changes from uncorrelated to long-range correlated as duration of a person’s solar exposure increases. The slopes of calculated WT power vary from 0, in the uncorrelated case for persons with erratic activities in reference to their UVR exposure, to close to 1 in the case of long-range correlated pUVR data, for persons spending longer periods in the sun. Peaks in the WT power spectra are also found, pointing to the existence of characteristic times in sun exposure behavior. Characteristic peaks at approximately 15 minutes, half an hour and an hour are present in all pUVR data, while persons with longer sun exposure have additional peaks at longer periods