Research On Characteristics Of Skin Ultraviolet Exposure With Rotating Manikins

IntroductionScientific evidence indicates that high levels of exposure to ultraviolet increase the risk of skin cancer and other sunlight-related skin damage, and also accelerate skin aging. So many researchers strive to study the relationship between UV and sun-related skin diseases, which urgently requires the quantitation of individual skin UV.Early studies just used local ambient UV to represent personal exposure does, which did not provide a reliable estimate of the received UV. Recently some researchers adopted other techniques, such as polysulphone dosimeters and questionnaires, to assess the individual skin UV during short term. However there are some limits to calculate the UV exposure in long term.To explore a better assessment approach, we described the characteristics of skin ultraviolet exposure with rotating manikins in Shenyang, and provided certain suggestion about individual UV protection. Meanwhile we established the personal ambient exposure ratios, which can solve the monitoring problem of facial skin UV exposure and identify areas for further research.Methods1. UV Exposure Model with Rotating ManikinsAccording to the virtue of the complex surface geometry, we fixed various UV monitors (Model: SUT-T, Tolay Techno Inst, Made in Japan) on different anatomical sites of the rotating manikins. The included angles between vertical axis and monitors on head, cheek and chest are respectively 15 degrees, 5 degrees, 10 degrees. The monitors on shoulders are almost horizontal. However the location of the monitor on nose cannot be controlled well, so we just fixed it under eye sockets and kept it the same direction with nasal tip.2. UV Measurements The specific monitoring was done during several days with clear weather before and after the Vernal Equinox, the Summer Solstice, the Autumnal Equinox and the Winter Solstice in Shenyang. And there is no cover at the monitoring site.Finishing the calibration of various UV monitors, we adjusted the manikins on the horizon and kept it rotating at the speed of 10 circles per minute. Every 15 minutes we recorded the data (kJ/m~2) of UV monitors on each anatomical site. Meanwhile we obtained the ambient UV levels by a UV monitor on the horizontal plane. Besides, to assess the protective contribution to different anatomical sites, we chose some days to wear hat on the rotating manikins while monitoring.3. Data handling and analysisAfter handling the original data, we drew the scatterplots of the cumulative UV doses during every 15 minutes of each anatomical site in four seasons. According to special knowledge and the stability of figures, we rejected the data with large variation and screened the best data. Then we described the characteristics of skin UV exposure of rotating manikins and ambient UV.Meanwhile, after checking the data integrity, we computed the cumulative UV doses of each anatomical site from 9:00 to 15:00. And we respectively compared them with the corresponding cumulative ambient UV. Then we can analyze the features of different personal-ambient exposure ratios. Besides we also compared the cumulative UV doses of facial exposure, with the ones of shoulders and chest, to complete the transition among them.Moreover, we compared the different data before and after wearing hat/ snowing. So they can reflect the influence of hat and snow reflection.ResultsThere is some relationship between ambient UV and solar elevation angles during the representative dates in four seasons. They are well in concordance with tendency. Their curves are almost parabola. In summer, the numerical values and the variation are largest. They are similar in spring and autumn, and both relatively smaller than in summer, while they are smallest in winter.The characteristics of skin ultraviolet exposure on various anatomical sites of rotating manikins are different from those of ambient UV during daytime. There are differences both on the doses and the variation in seasons. Among them, the characteristics of UV exposure on the shoulders, chest and head are similar with those of ambient UV. The most difference is the actual numerical value. The variances are smaller when the solar elevation angles are relatively small in winter and early morning or toward evening during other seasons. Besides, the characteristics of UV exposure on the cheek are quite particular. First the cumulative UV doses are generally small. Second, the curves are not smooth in spring, autumn and winter, the ones in summer look like as the shape of "M".The results show than there is large variation among the personal-ambient exposure ratios of the same anatomical site on rotating manikins. The seasonal variations are significant (P<0.05). The variations are less in the same season. The standard deviations are small and the means of ratios are representative in different seasons. The ratios of various anatomical sites in winter are highest, lower in spring and autumn, and lowest in summer. The extent of variations of the means is large for influence except shoulder. Meanwhile the ratios of head doses to chest doses are steadiest (just around 1.3 all the year) among different anatomical sites, others exist certain seasonal variations.The data before and after snowing, indicates the reflection of UV from snow is considerable. The actual influences on various anatomical sites are different. To shoulder, although it is a little weak, reflection can increase about 20% UV. In our study, hat can reduce the UV doses. The protection to head is stronger (almost 90%), which differs in degree to various anatomical sites.Conclusions1. In Shenyang, there are seasonal differences among the characteristics of skin ultraviolet exposure on various anatomical sites of rotating manikins and ambient UV during daytime. Among them, the characteristics of UV exposure on the shoulders, chest and head are similar with those of ambient UV, while ones on the cheek just look like as the shape of "M" in summer. Compared on the UV dose, it shows that ambient>shoulder>head >chest>cheek.2. In Shenyang, it is suitable to calculate different means in four seasons about the personal ambient exposure ratios of each anatomical site of rotating manikins, in which winter is higher. Meanwhile the ratios of head doses to chest doses are steadiest (just around 1.3 all the year), others exist certain seasonal variations.3. It indicates the reflection of UV from snow is considerable. Hat can reduce the UV doses. The protection to head is stronger, which differs in degree to various anatomical sites.