Characterisation and evaluation of a miniaturised polyphenylene oxide dosimeter

Abstract

In light of the ever changing composition of the Earth's atmosphere and the consequences of ultraviolet (UV) radiation for the biological environment, it is important to be able to determine the specific ultraviolet radiation levels that reach plants and humans on the Earth's surface. Dosimetry is a technique that is commonly employed to measure UV exposures to an object or subject. Miniaturised dosimeters using polysulphone have previously been used to measure received surface exposures by plants and humans, for exposure periods of up to one day. Larger dosimeters using polyphenylene oxide (PPO) as the photoactive material have successfully recorded UV exposures for up to seven days. A combination of a miniaturised dosimeter with PPO as the photoactive material has been developed in this research. An examination of the miniaturised PPO dosimeter for: the dark reaction, repeatability of measurement, dose response and the cosine response was completed. Two field tests comparing change in absorbance measurements for both large and miniaturised dosimeters were also undertaken. The results show the miniaturised PPO dosimeter to have the same dosimeter characteristics as the larger dosimeter and to provide results in the field consistent with those of the larger dosimeters. Consequently the miniaturised PPO dosimeters can be employed to evaluate the biologically effective UV to plants and humans. Successfully characterising the miniaturised PPO dosimeters allows greater number of measurements and increased potential for a wide range of environments to be tested in a cheaper and more time and measurement efficient way. Current research indicates that the financial cost of damage caused by UVB is extensive. Costs are incurred due to skin cancer in humans and reduced crop yields. Development of methods that allow for greater accuracy in recording specific radiation exposures will benefit society by providing information that enables action to be taken to reduce the future impact of UV radiation.