Optical Properties of Poly(2,6-Dimethyl 1,4 Phenylene Oxide) and it's potential for a long term dosimeter (original) (raw)
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Physics in Medicine and Biology, 2003
The optical properties of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) film have been characterised in order to develop an alternative method for UV dosimetry with a focus on long-term human exposure measurements. The dynamic range of PPO film was found to extend to 2 MJm -2 of broadband UV exposure independently of film thickness, providing an exposure range of roughly four summer days at subtropical latitudes. The sensitivity of the film to UV exposure was positively related to film thickness in the 20 to 40 μm range. Films of 40 μm thickness proved to be the most suitable for long-term human UV exposure measurements.
Applicability of the polyphenylene oxide film dosimeter to high UV exposures in aquatic environments
Previous research has proven that the Poly (2,6-dimethyl-1, 4-phenylene oxide) (PPO) dosimeter is capable of receiving both in-air and underwater UV exposures that are significantly greater than those of the more commonly used polysulphone dosimeter, within a range of accuracy close to what would be expected of dosimetric measurements made in-air provided that the necessary calibrations are completed correctly by factoring in different atmospheric column ozone levels, SZA ranges, varying water turbidity and DOM levels. However, there is yet to be an investigation detailing the performance of the PPO dosimeter and its ability to measure UV in an actual field environment over an extended period of time. This research aims to bridge this gap in the knowledge by presenting a measurement campaign carried out in two real world aquatic environments and a simulated sea water environment using a batch of PPO dosimeters set at different depths and aligned to a range of different angles and geographical directions by means of attachment to a custom built dosimeter submersible float (DSF) unit over the space of a year at a sub-tropical location. Results obtained from this measurement campaign were used to compute a Kd value for the sea water in each particular season. These Kd values where found to be in close agreement to standalone Kd values derived from results taken using a standard calibrated spectrometer in the same sea water.
Journal of Photochemistry and Photobiology B: Biology, 2013
The dosimetric properties of the recently introduced UV dosimeter based on 16 lm PVC film have been fully characterised. Drying the thin film in air at 50°C for at least 28 days was found to be necessary to minimise the temperature effects on the dosimeter response. This research has found that the dosimeter response, previously reported to be mainly to UVB, has no significant dependence on either exposure temperature or dose rate. The dosimeter has negligible dark reaction and responds to the UV radiation with high reproducibility. The dosimeter angular response was found to have a similar pattern as the cosine function but deviates considerably at angles larger than 70°. Dose response curves exhibit monotonically increasing shape and the dosimeter can measure more than 900 SED. This is about 3 weeks of continuous exposure during summer at subtropical sites. Exposures measured by the PVC dosimeter for some anatomical sites exposed to solar radiation for twelve consecutive days were comparable with those concurrently measured by a series of PPO dosimeters and were in line with earlier results reported in similar studies.
Poly (2, 6-dimethyl-1, 4-phenylene oxide) (PPO) film is a useful dosimetric tool for measuring solar UV in underwater and terrestrial environments. However, little is known about how the response of PPO changes with fluctuations in atmospheric ozone and also to seasonal variations. To resolve this issue this manuscript presents a series of long-term in-air solar erythemal response measurements made over a year from 2007 to 2008 with PPO. This data showed that the PPO dose response varies with modulations of the solar spectrum resulting from changes in season and atmospheric ozone. From this it was recommended that PPO only be calibrated in the season in which it is to be used at the same time as measurements were being made in the field. Extended solar UV measurements made by PPO with a neutral density filter (NDF) based on polyethylene are also detailed. These measurements showed that the lifetime of PPO could be extended by five days before saturation. As the dynamic range for PPO is known to be five days during summer at a sub-tropical location, the advantage of using the NDF is that half the number of dosimeters is needed to be fabricated and measured before and after exposure. This is the authors' final corrected accepted version of: Schouten, Peter and Parisi, Alfio and Turnbull, David (2010) Usage of the polyphenylene oxide dosimeter to measure annual solar erythemal exposures. Photochemistry and Photobiology, 86 (3). pp. 706-710. ISSN 0031-8655 Accessed from USQ ePrints
Potential of phenothiazine as a thin film dosimeter for UVA exposures
Photochemical & Photobiological Sciences, 2005
The research reported in this paper on the changes in absorbance and the calibration of a proposed UVA (320-400 nm) dosimeter have established the phenothiazine/mylar combination as a potential UVA dosimeter for population studies of UVA exposures. The change in optical absorbance at 370 nm was employed to quantify the UVA exposures. This change starts to saturate at approximately 0.3. This relates to solar UVA exposures at a sub-tropical site on a horizontal plane of approximately three to four hours. The shape of this calibration curve varies with the season. This can be overcome in the same manner as for polysulphone where the dosimeter is calibrated for the conditions that it will be employed to measure the UVA exposures.
Development and characterisation of an ultra-long exposure UV dosimeter
2014
Excessive exposure to solar ultraviolet (UV) radiation is known to have detrimental effects on human health, some of which are cumulative in nature with impacts that may arise after years and decades of exposure. Therefore, it is important that the risk associated with prolonged UV exposure can be investigated; this requires long-term studies in which large-dose measurements can be accurately quantified. Chemically-based UV dosimeters have been widely used to measure personal UV exposure since 1976. Despite the development of electronic UV dosimeters, chemical dosimeters maintain their suitability in human exposure research as versatile, labour- and cost-effective UV monitors that require no power. The main limitation of existing chemical dosimeters is their short dynamic measurement range, as they are saturated after relatively short exposure times. Consequently, prolonged personal UV exposures are estimated either from measurements spanning just a few days, with high uncertainty, ...
Polysulphone film thickness and its effects in ultraviolet radiation dosimetry
Polysulphone film thickness and the effects on the dose calibration in ultraviolet radiation dosimetry were investigated. Compared to those obtained with the dose calibration for the 45 μm thick film the erythemal exposures determined from the dose calibrations for the 18, 20 and 30 μm thick film ranged from 33% to -45%. The absolute of the differences averaged to 22%, 37% and 19% for the 18, 20 and 30 μm thick respectively. The variations in the dose response of polysulphone film with different thickness have shown that the dose response is highly dependent on the film thickness and highlighted the importance of employing polysulphone film of consistent and reproducible thickness in ultraviolet photobiology research.
Usage of the Polyphenylene Oxide Dosimeter to Measure Annual Solar Erythemal Exposures
Photochemistry and Photobiology, 2010
Poly (2, 6-dimethyl-1, 4-phenylene oxide) (PPO) film is a useful dosimetric tool for measuring solar UV in underwater and terrestrial environments. However, little is known about how the response of PPO changes with fluctuations in atmospheric ozone and also to seasonal variations. To resolve this issue this manuscript presents a series of long-term in-air solar erythemal response measurements made over a year from 2007 to 2008 with PPO. This data showed that the PPO dose response varies with modulations of the solar spectrum resulting from changes in season and atmospheric ozone. From this it was recommended that PPO only be calibrated in the season in which it is to be used at the same time as measurements were being made in the field. Extended solar UV measurements made by PPO with a neutral density filter (NDF) based on polyethylene are also detailed. These measurements showed that the lifetime of PPO could be extended by five days before saturation. As the dynamic range for PPO is known to be five days during summer at a sub-tropical location, the advantage of using the NDF is that half the number of dosimeters is needed to be fabricated and measured before and after exposure. This is the authors' final corrected accepted version of: Schouten, Peter and Parisi, Alfio and Turnbull, David (2010) Usage of the polyphenylene oxide dosimeter to measure annual solar erythemal exposures. Photochemistry and Photobiology, 86 (3). pp. 706-710. ISSN 0031-8655 Accessed from USQ ePrints
Journal of Photochemistry and Photobiology B: Biology, 2013
The spectral response of solvent-cast polyvinyl chloride (PVC) thin film suitable for use as a long-term UV dosimeter has been determined by measuring the UV induced change in the 1064 cm À1 peak intensity of the PVC's infrared (IR) spectra as a function of the wavelength of the incident radiation. Measurements using cutoff filters, narrow band-pass filters and monochromatic radiation showed that the 16 lm PVC film responds mainly to the UVB band. The maximum response was at 290 nm and decreasing exponentially with wavelength up to about 340 nm independent of temperature and exposure dose. The most suitable concentration (W/V%) of PVC/Tetrahydrofuran solution was found to be 10% and the best thickness for the dosimeter was determined as 16 lm.