Controlling sunbathing safety during the summer holidays - The solar UV campaign at Baltic Sea coast in 2015

Exposure to solar UV radiation of Polish teenagers after the first COVID-19 lockdown in March-April 2020

In Poland, schools were closed from March to June 2020 due to the COVID-19 epidemic. During the lockdown (March-April), everyone was advised to stay at home. From May, students were allowed to spend time outdoors. We examine their exposure to solar UV radiation during the period of virtual learning at schools (May-June), vacations (July-August) and the first month of typical learning (September). Primary and high school students aged 12-18 completed a questionnaire on the details of their outdoor activities and the weather at the exposure site. A total of 146 anonymous questionnaires were registered for the study. The survey responses provided input to a radiative transfer model to estimate erythemal and vitamin D doses obtained by teenagers during outdoor activities. The results from 48% of the questionnaires indicated that students' exposure exceeded 1 minimal erythema dose (MED) during the day. Corresponding doses of sun-synthesized vitamin D, in excess of 1000 international units (IU) and 2000 IU, were found in 77% and 66% of the surveys, respectively. Only 12% of the teenagers declared that they use sunscreen. The overexposure (> 1 MED) increased with age. It was found in 72% and 26% of surveys among the students aged 17-18 and 12-14, respectively. Teenagers seem to have tried to compensate for the lack of sunlight during the lockdown by engaging in outdoor activities permitted since May. While those activities could have improved their vitamin D levels, they also put them at a higher risk of developing erythema.

Review of Wearable and Portable Sensors for Monitoring Personal Solar UV Exposure

Sunlight is one of the main environmental resources that keeps all the organisms alive on earth. The ultraviolet (UV) radiation from the sun is essential for vitamin D synthesis in the human body, which is crucial for bone and muscle health. In addition, sun exposure also helps to reduce the risk of some cardiovascular diseases and cancers. However, excessive UV exposure can lead to adverse effects, including some eye diseases, premature aging, sunburn and skin cancers. The solar UV irradiance itself depends on many environmental factors. In fact, the UV index reported in weather forecasts is an estimation under cloudless conditions. Personal UV exposure also depends on one's outdoor activities and habits. Furthermore, the UV intake depends on the skin sensitivity. Therefore, there is a need for research into monitoring the optimal daily UV exposure for health benefits, without developing potential health risks. To facilitate the monitoring of solar UV intensity and cumulative dose, a variety of UV sensors have been developed in the past few decades and many are commercially available. Examples of sensors being marketed are: portable UV dosimeter, wearable UV radiometer, personal UV monitor, and handheld Solarmeter®. Some of the UV sensors can be worn as personal health monitors, which promote solar exposure protection. The paper provides a comprehensive review of the wearable and portable UV sensors for monitoring personal UV exposure, including a discussion of their unique advantages and limitations. Proposals are also presented for possible future research into reliable and practical UV sensors for personal UV exposure monitoring.

Numerical estimations of the daily amount of skin-synthesized vitamin D by pre-school children in Poland

According to Polish guidelines, children need a daily dose of 600-1000 I·U. vitamin D, which could be skin-synthesized in the period May to September, after at least 15 min solar exposure between 10 am and 3 pm with uncovered forearms and lower legs. In Poland, doctors only prescribe oral supplementation to infants and small children up to 2 years old, rarely for the older children. Numerical estimates of the daily amount of vitamin D (expressed in I.U. vitamin D taken orally) due to the solar exposure for preschoolers have been made on the basis of an observation campaign in Warsaw, Poland. In the period from April to September, the observations of children's clothing of age 4-6 years and the measurements of UV index were carried out in the kindergarten playground and a nearby park (52.31^oN, 21.06°E). It appears, that longer exposures (~45 min) are needed to gain the recommended dose. However, the estimation is burden with large uncertainties. The alternative scenario is to allow children to play outside for as long as possible without getting sunburn, i.e. until the personal erythemal threshold is reached. Then, sunscreens should be applied.

Ultraviolet radiation sensors: a review

Knowledge of when to actively modify outdoor sun protective behaviour is crucial for sun safety and should be based upon personal susceptibility to sunburn and the intensity of the ultraviolet radiation dose during outdoor exposure. To facilitate measurements of dose and exposure, non-scientific and research-grade instruments measuring different exposure parameters of solar radiation are commercially available. These devices have been marketed as weather stations, purpose-built UVI display stations, portable dosimeters, handheld solarmeters, watches, and even stickers that can be worn. According to their measurements, the public can be educated and reminded to adopt appropriate sun safety practices such as limiting midday sun exposure, seeking shade, wearing protective clothing such as a broad-brimmed hat, and regularly applying and reapplying broad-spectrum sunscreen. There are many different commercial devices and smart phone applications (apps) that allow the public to be informed about current ultraviolet radiation levels in their immediate area, but each aims to enable the public to practise good sun safety behaviour. Naturally, each device is not without its various limitations and unique advantages. This study explores the ways in which ultraviolet radiation sensors can provide an accurate and highly convenient way of practising good sun safety behaviour in various contexts of high sun exposure such as playgrounds, tourist attractions, workplaces, and swimming pools. However, the author advises caution on the use of personal meters that have not been validated for their reliability and accuracy as public health tools.

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.

Perspectives of UV nowcasting to monitor personal pro-health outdoor activities

Nowcasting model for online monitoring of personal outdoor behaviour is proposed. It is envisaged that it will provide an effective e-tool used by smartphone users. The model could estimate maximum duration of safe (without erythema risk) outdoor activity. Moreover, there are options to estimate duration of sunbathing to get adequate amount of vitamin D₃ and doses necessary for the antipsoriatic heliotherapy. The application requires information of starting time of sunbathing and the user's phototype. At the beginning the user will be informed of the approximate duration of sunbathing required to get the minimum erythemal dose, adequate amount of vitamin D₃, and the dose necessary for the antipsoriatic heliotherapy. After every 20-min the application will recalculate the remaining duration of sunbathing based on the UVI measured in the preceding 20 min. If the estimate of remaining duration is <20 min the user will be informed that the deadline of sunbathing is approaching. Finally, a warning signal will be sent to stop sunbathing if the measured dose reaches the required dose. The proposed model is verified using the data collected at two measuring sites for the warm period of 2017 (1st April-30th September) in large Polish cities (Warsaw and Lodz). First instrument represents the UVI monitoring station. The information concerning sunbathing duration, which is sent to a remote user, is evaluated on the basis of the UVI measurements collected by the second measuring unit in a distance of ~7 km and 10 km for Warsaw and Lodz, respectively. The statistical analysis of the differences between sunbathing duration by nowcasting model and observation shows that the model provides reliable doses received by the users during outdoor activities in proximity (~10 km) to the UVI source site. Standard 24 h UVI forecast based on prognostic values of total ozone and cloudiness appears to only be valid for sunny days.