Continuing benefits of the Montreal Protocol and protection of the stratospheric ozone layer for human health and the environment

The protection of Earth's stratospheric ozone (O3) is an ongoing process under the auspices of the universally ratified Montreal Protocol and its Amendments and adjustments. A critical part of this process is the assessment of the environmental issues related to changes in O3. The United Nations Environment Programme's Environmental Effects Assessment Panel provides annual scientific evaluations of some of the key issues arising in the recent collective knowledge base. This current update includes a comprehensive assessment of the incidence rates of skin cancer, cataract and other skin and eye diseases observed worldwide; the effects of UV radiation on tropospheric oxidants, and air and water quality; trends in breakdown products of fluorinated chemicals and recent information of their toxicity; and recent technological innovations of building materials for greater resistance to UV radiation. These issues span a wide range of topics, including both harmful and beneficial effects of exposure to UV radiation, and complex interactions with climate change. While the Montreal Protocol has succeeded in preventing large reductions in stratospheric O3, future changes may occur due to a number of natural and anthropogenic factors. Thus, frequent assessments of potential environmental impacts are essential to ensure that policies remain based on the best available scientific knowledge.

Efficacy of a facial-aging web app on sun protection behaviors among primary school students in Iran: a randomized controlled trial

BACKGROUND

Skin cancers resulting from excessive exposure to solar ultraviolet (UV) radiation are on the rise. This study aims to investigate the impact of facial-aging app intervention on promoting safe and healthy behaviors and its influence on reducing students' UV exposure.

METHOD

Utilizing a Pretest-Posttest repeated-measures design, we developed a theory-guided web app on the WhatsApp platform, named the Sunshine and Skin Health app. This app allows users to visualize their altered faces in three stages of adolescence, middle age, and old age based on sun protection behavior. The intervention continued within WhatsApp, incorporating 27 health messages grounded in the PMT theory, eight educational files, and a skin cancer video clip. The primary outcome is the change in sun protection behavior between the two groups (intervention and control) immediately after the intervention (T2) and the secondary outcome is the change in sun protection behavior between the two groups at 3 months follow-up (T3). The data are analyzed in SPSS 22 and a significance level of 0.05 is considered.

RESULTS

The results revealed no significant difference between the two groups before the intervention. However, in the intervention group, there were significant differences in the utilization of sunglasses, hats, and sunscreen in the last month, as well as sunscreen reapplication after washing their hands and face, both immediately after the intervention and at the 3-month follow-up, compared to the control group (P = 0.001). Furthermore, a significant intervention effect, time effect, and interaction effect between group and time were observed in behaviors related to using sunscreen in the last month and sunscreen reapplication after washing hands and face (P = 0.001). Specifically, the intervention group exhibited a significant difference from Time 1 to 2 and from Time 1 to 3 (p = 0.001), but no significant difference from Time 2 to 3. In contrast, the control group did not show any significant differences over time.

CONCLUSIONS

This study indicated that the Facial-Aging web app can effectively encourage safe behaviors in sunlight. To ensure the maintenance and sustainability of these behaviors over the long term, it is crucial to consider implementing booster sessions.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials IRCT20200924048825N1. Registered prospectively on 8 February 2021.

Health risks of extended exposure to low-level UV radiation - An analysis of ground-based and satellite-derived data

This study aims to indicate the importance of revising current health recommendations concerning the duration of exposure and individual sensitivity of the skin to solar ultraviolet (UV) radiation. For this purpose, a 16-year data series (2005-2020) of erythemal radiant exposure (H_er) and UV index (UVI) for Serbia was analyzed. The UV-related risk was estimated for lighter skin (skin phototypes I-IV) under prolonged exposure on days when maximum UVI was below the recommended protection threshold (UVI_low days, for UVI < 3). Risk assessment was performed for seasonal exposure using satellite-derived data (OMUVBd product) previously validated by ground-based measurements in Novi Sad. The assessment of harmful effects included an analysis of the relation between the daily maximum UVI and the corresponding daily H_er, the occurrence of UVI_low days, the exceedance of minimal erythema dose (MED), and the minimum duration of exposure to induce erythema (t_MED) for all lighter skin phototypes. It was found that the share of UVI_low days in the total number of days in Serbia increases with the latitude, with the highest percentage in winter (up to 69.454%) and the lowest in summer (up to 3.468%). The results show that the daily H_er frequently exceeded the harmful threshold for lighter skin phototypes I-IV (on average by 91.521, 84.923, 70.556, and 56.515%, respectively) on UVI_low days. It was found that prolonged exposure on days with a maximum of UVI = 2 poses a significant risk of erythema for all lighter skin phototypes, even for a duration of 3 h in the middle of the day, as well as medium risk for UVI = 1, and an absence of risk for UVI = 0. The results suggest that health recommendations should be revised, especially in the mid-latitudes, where the share of UVI_low days is large, and in areas where the population is predominantly lighter-skinned.

Persistent extreme ultraviolet irradiance in Antarctica despite the ozone recovery onset

Attributable to the Montreal Protocol, the most successful environmental treaty ever, human-made ozone-depleting substances are declining and the stratospheric Antarctic ozone layer is recovering. However, the Antarctic ozone hole continues to occur every year, with the severity of ozone loss strongly modulated by meteorological conditions. In late November and early December 2020, we measured at the northern tip of the Antarctic Peninsula the highest ultraviolet (UV) irradiances recorded in the Antarctic continent in more than two decades. On Dec. 2nd, the noon-time UV index on King George Island peaked at 14.3, very close to the largest UV index ever recorded in the continent. On Dec. 3rd, the erythemal daily dose at the same site was among the highest on Earth, only comparable to those recorded at high altitude sites in the Atacama Desert, near the Tropic of Capricorn. Here we show that, despite the Antarctic ozone recovery observed in early spring, the conditions that favor these extreme surface UV events persist in late spring, when the biologically effective UV radiation is more consequential. These conditions include long-lasting ozone holes (attributable to the polar vortex dynamics) that often bring ozone-depleted air over the Antarctic Peninsula in late spring. The fact that these conditions have been occurring at about the same frequency during the last two decades explains the persistence of extreme surface UV events in Antarctica.

The Shadow Rule, the UV Index, and the 5S Steps in the Tropics

Solar ultraviolet radiation (UVR) induces the production of vitamin D (VD), but it also causes erythema and skin cancer among other diseases. The amount of UVR to get benefit and avoid harm is unknown. Some principles were proposed to provide accessible information on how to avoid overexposure to the Sun. They are (1) the Shadow Rule (SR); (2) the UV Index (UVI); and (3) the Slip, Slop, Slap, Seek, Slide (5S) steps. This work discusses these principles in the tropics, considering measurements of solar UVR, total ozone column, and cloudiness. Indeed, the SR leads to overexposures. The UVI is adequate for cloudless skies, but it does not consider radiation enhancement events by clouds. "Seek shade" in the 5S steps should be more emphasized as it is both the most efficient step in terms of avoiding direct sun and the friendliest step toward the environment. Therefore, photoprotection attitudes in the tropics should focus on the UVI and the 5S steps in addition to considering both VD sufficiency and environmental outcomes. The SR is clearly inaccurate.

Sun ultraviolet radiation in Ibarra, Ecuador and its relation to vitamin D synthesis

In the present work, we determined the necessary time to unchain the synthesis of vitamin D for a phototype II skin in Ibarra, Ecuador. In a specific sky situation, the range of exposure time at Sun radiation is 4 to 6 minutes depending on the month of the year, but with clouds, it is needed about 70% more exposure time. This time range is easily reached in normal conditions, but during a lockdown period, as in pandemic situations like the COVID 19 one or for people that need to live, work or study inside, if they are exposed to the direct Sun for the minutes indicated above, they will have a natural vitamin D supplement that will improve its health.

Maximum UV Index Records (2010–2014) in Quito (Ecuador) and Its Trend Inferred from Remote Sensing Data (1979–2018)

To prevent adverse health effects, the World Health Organization promotes the diffusion of the ultraviolet radiation index (UVI), with messages promoting precautionary behaviors, through a scale that considers extreme UVI values to be larger than 11.0. This scale came from a proposal from Canada, a country with a mostly light-skinned population, which experiences maximum UVI values up to 10.0. A modified scale was proposed, adapted to the skin types and the UVI levels in South America, which considers extreme values larger than 16.0. The records from 2010 to 2014 indicated that UVI is frequently larger than 11.0 (40.0–76.1% of the days per month) in Quito (Ecuador). The number of days per month with levels larger than 16.0 varied between 0.7% and 32.0%. We found that the maximum UV index levels do not occur necessarily around the local solar noontime. As the basis for a self-warning system in Quito and based on their skin type and UVI levels, people should know the exposure time before damage can take place. The Tropospheric Emission Monitoring Internet Service (TEMIS) computed the UVI at local solar noontime and under clear-sky conditions. The records from 2010 to 2014 were congruent with the corresponding TEMIS values. We did not identify any trend of the daily TEMIS UVI values during 1979 to 2018, which, used as a proxy, suggested the real UVI levels in Quito during 2010 to 2018 varied in a range similar to 1979–2009.

Changes in the total ozone content over the period 2006 to 2100 and the effects on the erythemal and vitamin D effective UV doses for South America and Antarctica

Recent studies show that the ozone layer will recover by the middle part of this century. This is a significant result arising from the Montreal Protocol, and highlights the success of this environmental protection agreement. Climate change projections show that Total Ozone Content (TOC) levels will increase significantly by the end of this century, mainly at higher latitudes. This increase may result in a reduction of the adverse effects of UV radiation overexposure. By contrast, reduced UV radiation levels at the surface of the Earth can result in reduced levels of vitamin D synthesis among the inhabitants of these regions. In this study we provide estimates for the UVI, erythemal, and vitamin-D weighted daily doses for ten different locations in South America and Antarctica. Our calculations were based on ozone projections provided by climate models set forth in the last IPCC report. Results show that the increase of TOC levels in middle and high latitude regions may result in decreased UVI and UV doses throughout the century. In high latitudes, erythemal doses and vitamin D synthesis doses may be reduced by up to 22 and 39%, respectively, if anthropogenic emissions continue to rise throughout the century. Furthermore, there may be reductions of up to 9 and 12%, respectively, in mid-latitudes (20°S to 35°S). Significant variations at Equatorial sites were not observed. In most of South America, the attenuation in UVR caused by increases in TOC during the 21^st century is neither enough to promote protective effects from this radiation, nor for the lack of UVR for vitamin D synthesis. The incidence of UVR in tropical and sub-tropical areas of the continent will continue to be a public health risk for the entire 21^st century during all seasons, regardless of the climatic scenarios. Our results can be used as an important tool for health studies focusing on the excess and/or lack of sun exposure.

Solar UV Radiation in Saint-Denis, La Réunion and Cape Town, South Africa: 10 years Climatology and Human Exposure Assessment at Altitude

Solar ultraviolet radiation (UVR) monitoring is important since it depends on several atmospheric parameters which are associated with climate change and since excess solar UVR exposure and has significant impacts on human health and wellbeing. The objective of this study was to investigate the trends in solar UVR during a decade (2009–2018) in Saint-Denis, Reunion Island (20.9°S, 55.5°E, 85 m ASL) and Cape Town, South Africa (33.97°S, 18.6°E, 42 m ASL). This comparison was done using total daily erythema exposure as derived from UVR sensors continuously at both sites. Climatology over the 10-year period showed extreme UVR exposure for both sites. Slight changes with opposite trends were found, +3.6% at Saint-Denis and −3.7% at Cape Town. However, these two sites often experience extreme weather conditions thereby making the trend evaluation difficult. Human exposure assessment was performed for hiking activities at two popular high-altitude hiking trails on the Maïdo–Grand Bénare (Reunion) and Table Mountain (Cape Town) with a handheld radiometer. Extreme exposure doses of 64 SED and 40 SED (Standard Erythemal Dose, 1 SED = 100 J.m−2) were recorded, respectively. These high exposure doses highlight the importance of raising public awareness on the risk related to excess UVR exposure at tourist sites, especially those at high altitude.

Public Health Messages Associated with Low UV Index Values Need Reconsideration

Overexposure to ultraviolet (UV) radiation is the main modifiable risk factor for skin cancer. The Global Solar Ultraviolet Index (UVI) was introduced as a tool to visualize the intensity of UV radiation on a certain day, which should enable and encourage people to take appropriate protective measures. The ‘low’ exposure category of the UVI, defined by a rounded UVI value of 0, 1 or 2, was linked to the health message ‘No protection required’ by the World Health Organization and partner organizations. However, published evidence corroborating this advice is not available. To evaluate the erythemal risk of low UVI days, we analyzed 14,431 daily time series of ambient erythemal irradiance data measured at nine stations of the German solar UV monitoring network during the years 2007–2016. We analyzed the proportion of days in the sample for which ambient erythemal doses calculated for various time intervals exceed average minimal erythemal doses (MEDs) of the Fitzpatrick skin phototypes I–VI to assess the potential for erythema arising from sun exposure on days with low UVI values. Additionally, we calculated for each day the minimum exposure duration needed to receive one MED. Our results indicate that on days with a UVI value of 0, risk of erythema is indeed negligible. Conversely, the abovementioned health message appears misleading when melano-compromised individuals (skin type I and II) spend more than 1.5 hours outdoors on days with a UVI value of 2. Under rare circumstances of prolonged exposure, MEDs of the two most sensitive skin types can also be exceeded even on days with a UVI value of 1. Hence, current WHO guidance for sun protection on days with low UVI values needs reconsideration.

Erythemal UV Radiation on Days with Low UV Index Values-an Analysis of Data from the German Solar UV Monitoring Network over a Ten-year Period

According to the World Health Organization and partner organizations, no protection against ultraviolet (UV) radiation is required on days with "low" values (i.e., values <3) of the Global Solar Ultraviolet Index (UVI). Erythemal irradiance (E_er ) data of such days were analyzed to evaluate this claim. Measurements from 9 stations of the German solar UV monitoring network from 2007 to 2016 yielded 14,431 daily E_er time series of low UVI days. Erythemal doses for certain fixed time intervals-acquired from measurements on horizontal planes-were compared with the average minimal erythemal dose (MED) of skin phototype II. Doses from days with rounded UVI values of 0 were insufficient to induce erythema and even on days with rounded UVI values of 1 doses exceeding 1 MED of skin type II could only be acquired under very specific circumstances of prolonged exposure. Conversely, sun exposure on days with rounded UVI values of 2 can indeed provide doses sufficient to induce erythema in skin type II after two hours around noon. In conclusion, our analyses do not support the claim of harmlessness currently associated with the entire low UVI exposure category in public guidance on interpretation of the UVI.

Human health in relation to exposure to solar ultraviolet radiation under changing stratospheric ozone and climate

The Montreal Protocol has limited increases in the UV-B (280-315 nm) radiation reaching the Earth's surface as a result of depletion of stratospheric ozone. Nevertheless, the incidence of skin cancers continues to increase in most light-skinned populations, probably due mainly to risky sun exposure behaviour. In locations with strong sun protection programs of long duration, incidence is now reducing in younger age groups. Changes in the epidemiology of UV-induced eye diseases are less clear, due to a lack of data. Exposure to UV radiation plays a role in the development of cataracts, pterygium and possibly age-related macular degeneration; these are major causes of visual impairment world-wide. Photodermatoses and phototoxic reactions to drugs are not uncommon; management of the latter includes recognition of the risks by the prescribing physician. Exposure to UV radiation has benefits for health through the production of vitamin D in the skin and modulation of immune function. The latter has benefits for skin diseases such as psoriasis and possibly for systemic autoimmune diseases such as multiple sclerosis. The health risks of sun exposure can be mitigated through appropriate sun protection, such as clothing with both good UV-blocking characteristics and adequate skin coverage, sunglasses, shade, and sunscreen. New sunscreen preparations provide protection against a broader spectrum of solar radiation, but it is not clear that this has benefits for health. Gaps in knowledge make it difficult to derive evidence-based sun protection advice that balances the risks and benefits of sun exposure.

Ozone-climate interactions and effects on solar ultraviolet radiation

This report assesses the effects of stratospheric ozone depletion and anticipated ozone recovery on the intensity of ultraviolet (UV) radiation at the Earth's surface. Interactions between changes in ozone and changes in climate, as well as their effects on UV radiation, are also considered. These evaluations focus mainly on new knowledge gained from research conducted during the last four years. Furthermore, drivers of changes in UV radiation other than ozone are discussed and their relative importance is assessed. The most important of these factors, namely clouds, aerosols and surface reflectivity, are related to changes in climate, and some of their effects on short- and long-term variations of UV radiation have already been identified from measurements. Finally, projected future developments in stratospheric ozone, climate, and other factors affecting UV radiation have been used to estimate changes in solar UV radiation from the present to the end of the 21^st century. New instruments and methods have been assessed with respect to their ability to provide useful and accurate information for monitoring solar UV radiation at the Earth's surface and for determining relevant exposures of humans. Evidence since the last assessment reconfirms that systematic and accurate long-term measurements of UV radiation and stratospheric ozone are essential for assessing the effectiveness of the Montreal Protocol and its Amendments and adjustments. Finally, we have assessed aspects of UV radiation related to biological effects and human health, as well as implications for UV radiation from possible solar radiation management (geoengineering) methods to mitigate climate change.

Are current guidelines for sun protection optimal for health? Exploring the evidence

Exposure of the skin to ultraviolet (UV) radiation is the main risk factor for skin cancer, and a major source of vitamin D, in many regions of the world. Sun protection messages to minimize skin cancer risks but avoid vitamin D deficiency are challenging, partly because levels of UV radiation vary by location, season, time of day, and atmospheric conditions. The UV Index provides information on levels of UV radiation and is a cornerstone of sun protection guidelines. Current guidelines from the World Health Organization are that sun protection is required only when the UV Index is 3 or greater. This advice is pragmatic rather than evidence based. The UV Index is a continuous scale; more comprehensive sun protection is required as the UV Index increases. In addition, a wide range of UVA doses is possible with a UVI of 3, from which there may be health consequences, while full sun protection when the UVI is "moderate" (between 3 and 5) may limit vitamin D production. Finally, the duration of time spent in the sun is an essential component of a public health message, in addition to the intensity of ambient UV radiation as measured by the UV Index. Together these provide the dose of UV radiation that is relevant to both skin cancer genesis and vitamin D production. Further education is required to increase the understanding of the UV Index; messages framed using the UV Index need to incorporate the importance of duration of exposure and increasing sun protection with increasing dose of UV radiation.

Critical appraisal of data used to infer record UVI in the tropical andes

When the data sets that suggested record high UVI values at Mt Licancabur, and Laguna Blanca, Bolivia are reviewed in full, we find that the reported peak values are incorrect, probably due to instrumental problems. These affect the UVB, UVA and PAR channels at different times and different solar zenith angles, with distinct diurnal patterns in each case. The outliers are consistent with errors that would result from build-up of ice or snow on the surface of the entrance dome, combined with incomplete baffling of light within the integrating spheres that form the entrance optic of these instruments, but we cannot unequivocally attribute them to this cause. The analysis shows that for all three channels, cloud enhancements over clear-sky values by a factor of ∼4 or more would be required to explain their highest values. Such repeated enhancements are not physically plausible and are more than twice those previously observed in the UV region. Further, at the time of peak reported UVB, the UVA cloud enhancement factor was less than 1.2 (i.e., UVA radiation was increased by less than 20% over clear-sky values), which implies that to explain the high UVB values, an atmospheric ozone amount (∼25 DU) far below the minimum ever observed would be required. The analysis also shows that the algorithm to convert from UVB to UVI is incorrect, and that if the correct algorithm had been used, the peak UVI values would have been even larger than reported. Disregarding the obviously incorrect measurements, the highest realistic values near solar noon from this dataset are in the range UVI = 25 ± 5, which is in agreement with previous estimates in the region.

Review of the Global Solar UV Index 2015 Workshop Report

The Global Solar UV Index was developed as an easy-to-understand measure of the amount of biologically-effective ambient solar ultraviolet radiation (UVR) at different locations on the earth's surface. Over the past few years, questions have been raised about the global applicability of the UV Index, about the evidence base for exposure risk thresholds and related protective measures, and about whether the overall impact of the UV Index could be improved with modifications. An international workshop was organized by several organizations, including the World Health Organization, to assess if current evidence was sufficiently strong to modify the UV Index and to discuss different ways it might be improved in order to influence sun-protective behavior. While some animal research suggests there may be no threshold effect, the relative importance of sub-erythemal doses of sunlight in causing skin cancer in humans remains unknown. Evidence suggests that regular use of sunscreen can prevent skin cancer and that sunglasses are an effective method of protecting the eyes from solar UVR. The UV Index as a risk communication tool continues to be useful for raising awareness and to support sun-protection behavior. Although there was agreement that guidance on the use of the UV Index could be improved, the workshop participants identified that strong health outcome-based human evidence would be needed as the basis for a revision. For the UV Index to be relevant in as many countries as possible, it should continue to be adapted to suit local conditions.

Effects of UVB radiation on grazing of two cladocerans from high-altitude Andean lakes

Climate change and water extraction may result in increased exposition of the biota to ultraviolet-B radiation (UVB) in high-altitude Andean lakes. Although exposition to lethal doses in these lakes is unlikely, sub-lethal UVB doses may have strong impacts in key compartments such as zooplankton. Here, we aimed at determining the effect of sub-lethal UVB doses on filtration rates of two cladoceran species (Daphnia pulicaria and Ceriodaphnia dubia). We firstly estimated the Incipient Limiting Concentration (ILC) and the Gut Passage Time (GPT) for both species. Thereafter we exposed clones of each species to four increasing UVB doses (treatments): i) DUV-0 (Control), ii) DUV-1 (0.02 MJ m²), iii) DUV-2 (0.03 MJ m²) and iv) DUV-3 (0.15 MJ m²); and estimated their filtration rates using fluorescent micro-spheres. Our results suggest that increasing sub-lethal doses of UVB radiation may strongly disturb the structure and functioning of high-altitude Andean lakes. Filtration rates of D. pulicaria were not affected by the lowest dose applied (DUV-1), but decreased by 50% in treatments DUV-2 and DUV-3. Filtration rates for C. dubia were reduced by more than 80% in treatments DUV-1 and DUV-2 and 100% of mortality occurred at the highest UVB dose applied (DUV-3).

Ultraviolet solar radiation in the tropical central Andes (12.0°S)

Ultraviolet (UV) solar irradiance measurements performed in the central Andes, Huancayo, Peru (12.0°S, 75.3°W, 3313 m asl) between January 2003 and December 2006 were used to analyse daily, monthly, and annual cycles of UV solar irradiance.

Environmental effects of ozone depletion and its interactions with climate change: progress report, 2015

The Environmental Effects Assessment Panel (EEAP) is one of three Panels that regularly informs the Parties (countries) to the Montreal Protocol on the effects of ozone depletion and the consequences of climate change interactions with respect to human health, animals, plants, biogeochemistry, air quality, and materials. The Panels provide a detailed assessment report every four years. The most recent 2014 Quadrennial Assessment by the EEAP was published as a special issue of seven papers in 2015 (Photochem. Photobiol. Sci., 2015, 14, 1-184). The next Quadrennial Assessment will be published in 2018/2019. In the interim, the EEAP generally produces an annual update or progress report of the relevant scientific findings. The present progress report for 2015 assesses some of the highlights and new insights with regard to the interactive nature of the effects of UV radiation, atmospheric processes, and climate change.

The Solar Spectrum in the Atacama Desert

The Atacama Desert has been pointed out as one of the places on earth where the highest surface irradiance may occur. This area is characterized by its high altitude, prevalent cloudless conditions and relatively low columns of ozone and water vapor. Aimed at the characterization of the solar spectrum in the Atacama Desert, we carried out in February-March 2015 ground-based measurements of the spectral irradiance (from the ultraviolet to the near infrared) at seven locations that ranged from the city of Antofagasta (on the southern pacific coastline) to the Chajnantor Plateau (5,100 m altitude). Our spectral measurements allowed us to retrieve the total ozone column, the precipitable water, and the aerosol properties at each location. We found that changes in these parameters, as well as the shorter optical path length at high-altitude locations, lead to significant increases in the surface irradiance with the altitude. Our measurements show that, in the range 0–5100 m altitude, surface irradiance increases with the altitude by about 27% in the infrared range, 6% in the visible range, and 20% in the ultraviolet range. Spectral measurements carried out at the Izaña Observatory (Tenerife, Spain), in Hannover (Germany) and in Santiago (Chile), were used for further comparisons.

Extreme UV index and solar exposures at Plateau Rosà (3500 m a.s.l.) in Valle d'Aosta Region, Italy

The purpose of this study is to assess personal exposures of skiers at the Alpine site of Plateau Rosà (45.9°N, 7.7°E, 3500 m a.s.l.), in the Valle d'Aosta region, Italy. The campaign was carried out on July 12th, 2011 during the summer ski season. A peak UVI value of 12.3, among the highest in Europe, was recorded on that day. Personal exposures (PE) were quantified using both polysulphone (PS) and poly-dimethyl phenylene oxide (PPO) dosimeters attached vertically to the cap because it is representative of the vertically oriented face of skiers. Exposure ratio (ER) defined as the ratio between PE and the corresponding ambient dose (i.e. erythemally weighted dose received by a horizontal surface) measured by a broad-band radiometer during the same exposure time of the subjects, was used to compare the results with previous studies. Skin color was also measured on the inner upper arm and on the cheek and differences in ITA (Individual Typology Angle) and a* (redness) values before and after exposure, were statistically analyzed. During the exposure period, the median PE (with PS) was 1.47 kJ m(-2) and that obtained by PPO was 1.15 kJ m(-2). The median of the ERs was 0.65 (min: 0.50, max: 0.83) considering the cumulative PS exposure and 0.46 (min: 0.29, max: 0.95) for PPO. An increase in ITAs on the exposed site (i.e. the skin became lighter) was observed after exposure. These results indicate that: a) for some skiers, the exposures were similar to those received on the horizontal plane; and b) the targeted population showed exposures above the occupational threshold limit value (TLV) defined by ICNIRP; c) the use of physical sunscreens which tend to leave a white cast, might have reduced skin color change. Nevertheless possible visible sun-induced skin-color changes could be observed after longer time intervals after exposure.

The consequences for human health of stratospheric ozone depletion in association with other environmental factors

Ozone depletion, climate and human health.

Ozone depletion and climate change: impacts on UV radiation

Percentage changes in the UV Index (UVI) for 2090 relative to 2015 due to changes in ozone (left) and aerosols (right) only. Large decreases are projected over Antarctica due to stratospheric ozone recovery. Increases are projected for parts of Asia due to decreases in aerosols, partly reversing the possible large reductions in UVI after the 1950s.