This proposed conversion model provides a means of using an illuminance reading to calculate the PpIX-weighted exposure dose. Dosimetry of dPDT may be carried out simply and at low cost using the presented method; however, the results presented may be used as a guide for those considering dPDT, without the need to conduct measurements themselves.

In this paper erythema effective UV radiant exposure data from the PHE solar network Chilton site for the 25 year period from 1991 to 2015 are presented. The year with the highest average daily erythema effective radiant exposure was 2003 at 1577 J m and the year with the lowest average daily radiant exposure was 2010 at 1149 J m. Overall, the average daily radiant exposure per year ranged from 5655 J m to 9.98 J m with the average being 1306 J m. A preliminary analysis of the data set is carried out. A statistically significant (p = 0.01) increase in annual radiant exposure of 4.4% per year was observed from 1991-1995. Thereafter a small decrease in annual erythema effective radiant exposure of 0.8% (p = 0.002) per year was observed from 1995-2015 with a slightly faster rate of decrease from 2000-2015 of 1.0% (p = 0.007) per year. In terms of seasonal analyses, a statistically significant increase in erythema effective UV radiant exposure of 5.1% (p = 0.02) per year in the summer during 1991-1995 has been found along with small decreases in spring and summer during 1995-2015 (-1.0%; p = 0.01 and -0.7%; p = 0.01 respectively) and 2000-2015 (-1.1%; p = 0.03 and -1.2%; p = 0.003 respectively). The data suggest that the erythema effective UV dose available for impacting public health has been decreasing in recent years.

Pilots should be warned of the potential high UVA exposure during flight and advised on the use of sunglasses. A windshield labeling system would allow the pilot to tailor their eye protection practices to that particular aircraft.

a b s t r a c tThe ultrafast decay rates of photoexcited C À 60 and C 2À 60 ions have been measured in the condensed phase. The mechanism for decay is internal conversion, and the decay rate is a strong function of the charge on the ion. A bottleneck in the ground state recovery has also been detected, and its interpretation is discussed.

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Evidence of an underlying trend in the dependence of erythema effective ultraviolet (UV) radiant exposure (H er ) on changes in the total ozone, cloud cover and aerosol optical depth (AOD) has been studied using solar ultraviolet radiation measurements collected over a 25-year period (1991-2015) at Chilton in the south of England in the UK.The monthly mean datasets of these measures corrected for underlying seasonal variation were analysed. When a single linear trend was fitted over the whole study period between 1991 and 2015, the analyses revealed that the longterm variability of H er can be best characterised in two subperiods (1991-2004 and 2004-2015), where the estimated linear trend was upward in the first period (1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004) but downward in the second period (2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015).Both cloud cover (CC) and total ozone (TO) were found to have a highly statistically significant influence on H er , but the influence of the AOD measure was very small. The radiation amplification factor (RAF) for the erythema action spectrum due to TO was −1.03 at constant levels of CC over the whole study period; that is, for a 1.0 % increase in TO, H er decreases by 1.03 %. Over the first period (1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004), the RAF related to CC was slightly higher at 0.97 compared to that for TO at 0.79. The proportion of the change in H er explained by the change in CC (47 %) was much greater than the proportion explained by changes in TO (8 %). For the second period (2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015), the pattern reversed, with the observed RAF related to TO being −1.25, almost double that of CC (−0.65). Furthermore, in this period the proportion of variation in H er explained by TO variation was 33 %, double that of CC at 16 %, while AOD changes had a negligible effect (1 %).When the data were examined separately for each season, for the first period (1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004) the greatest effect of TO and CC on H er (i.e. the largest RAF value) was found during spring. Spring was also the season during which TO and CC variation explained the greatest proportion of variability in H er (82 %). In the later period (2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015), the RAF and greatest influence of TO and CC were observed in winter (67 %) and the AOD effect explained a further 5 % variability in H er .This study provides evidence that both the increasing trend in H er for 1991-2004 and the decreasing trend in H er for 2004-2015 occur in response to variation in TO, which exhibits a small increasing tendency over these periods. CC plays a more important role in the increasing trend in H er for 1991-2004 than TO, whereas for 2004-2015, the decreasing trend in H er is less associated with changes in CC and AOD.

It is known that ultraviolet radiation (UVR) increases by 10-12% every 1000 m altitude; UVR at the 10 000 m of typical cruise altitude for commercial aircraft may be 2-3 times higher than at ground level. Information on the levels of solar UV exposures is essential for the assessment of the occupational risk of pilots developing sun-related eye disorders and skin cancers. The aim of the study was to investigate how UV hazard exposures can be measured during flights so that the occupational dose can be ascertained and compared with international guidance. This article describes the development of instrumentation for automated time-stamped spectral measurements which were collected using bespoke automation software. The software enables the advanced acquisition techniques of automated dark signal capture and multiband integration control optimizing the dynamic performance of the spectrometer over the full spectral range. The equipment was successfully tested in a number of aircraft and helicopter flights during 2012-2013 and illustrated in this article on an example of a Gatwick-Alicante flight.

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