北京地区人群对防晒霜的认知及使用情况

目的了解北京地区人群对防晒霜的认知及使用情况。方法采取问卷调查方式,进行面对面交谈,并填写调查问卷。结果80.3%(578/720)的人使用过防晒霜,女性明显高于男性(P<0.001)。开始使用防晒霜的年龄为8～60岁,平均28.4±22.0岁,平均使用时间8.1±21.7年。35.8%的男性、34%的中老年人、44.6%的初等文化程度及28.3%的Ⅳ,Ⅴ型皮肤的人群从未使用过防晒霜。女性及Ⅰ,Ⅱ型皮肤的人使用防晒霜比较规律。63.1%的人群使用防晒霜SPF值在15～30之间。17.3%的人不知道自己使用防晒霜的SPF值,以男性、中老年、初等文化者以及Ⅳ、Ⅴ型皮肤人群为主。有一半以上的人不知道防晒指数的意义。结论北京地区人群中使用防晒霜的比例较高。在对防晒霜的认知和使用,不同人群差异较大。     

Awarness to photodamage versus the actual use of sun protection methods by young adults

Objective There is accumulating evidence that in spite of the large campaigns against excessive solar exposure undertaken by dermatologists worldwide, children and adolescents are still spending long periods in the sun, and do not follow the recommended sun protection guidelines. The purpose of the present study was to evaluate sun exposure in a group of young Israeli adults and to compare it to their knowledge and application of the various sun protection methods. Methods 202 Caucasian volunteers, (mean age 21.4 ± 2.6), filled out detailed questionnaires on their sun exposure and sun protection habits. Results More than 80% of our study participants are regularly sun exposed for longer than 2 h per day whereas sunscreens are utilized only by 64.9%. Sunscreen use was significantly more prevalent in females than males (81.3% vs. 46.5%). The majority of sunscreen users and nonusers believed that sunscreen could prevent skin cancer (94.3% and 82.0%, respectively) and that these compounds can slow skin aging (90.8% and 76.4% respectively). The understanding of the meaning of the “SPF” was significantly higher in the sunscreen users (85%) than in the nonusers (62.0%). The majority of sunscreen users utilized less than 150 ml of the compound per year which is probably an inadequate amount for a year for full body protection. The two most common reasons for not using sunscreens regularly, were that the application is time consuming, and that sunscreens prevent tanning. Conclusion Our data reveals a discrepancy between a considerably good understanding of the need for sun protection and the still deficient application of these measures especially in young adult males.     

Sun awareness and sun protection practices in Malta

BACKGROUND: Concern regarding the rising incidence of melanoma and non-melanoma skin cancers in Malta has led to the organization of annual campaigns since the early 1990s. These aim to inform the public of the dangers of sun exposure and to promote sun protection. OBJECTIVE: To help guide future campaigns, a survey was carried out to evaluate current sun protection measures among the Maltese people and to assess their level of knowledge regarding harmful effects of the sun on the skin. STUDY DESIGN: A total of 559 pedestrians were interviewed in the main street of the capital city of Malta in the summer of 1999. RESULTS: Self-reported rates of regular sunscreen and hat use in adults exposed to the spring/summer sun between 10.00 h and 15.00 h were 51% and 32%, respectively, for leisure activities, and 25% and 37%, respectively, for outdoor work. Men reported using sunscreen less often than women during both leisure and work. The fairer-skinned outdoor workers actually reported making less use of a sunscreen and/or hat than their darker counterparts, and rates of sunscreen and/or hat use during leisure and work were not found to increase with the amount of time spent in the sun. Almost 75% of sunscreen users were using a sun protection factor of at least 15. Parents reported much higher rates of regular sunscreen and hat use by their young children than by themselves, with 87% of children under 12 years of age reported to be using sunscreen and 78% reported to be wearing a hat. The great majority knew that injudicious sun exposure is associated with skin cancer and skin ageing, but 48% were still regarding a suntan achieved without skin burning as 'healthy' The mass media was by far considered to be the main source of information for the general public regarding effects of the sun on the skin. CONCLUSIONS: The positive impact of past campaigns can be seen in the high reported rates of sun protection in children. However, much remains to be done with adults in order to change their attitude about a 'healthy suntan' and to convince them that it is worthwhile to protect themselves from the sun.     

Application of sunscreen − theory and reality

We present research on sunscreen use with possible pitfalls and discuss theory vs. reality. A literature review in PubMed was conducted using the terms ‘sunscreen application’, ‘sunscreen use’ and ‘sun protection factor’. The sun protection factor (SPF) of sunscreens are tested using a thickness of 2 mg/cm², but investigations show that sunscreen under natural conditions is applied insufficiently with amounts about 0.39 to 1.0 mg/cm², which decreases the protection factor considerably. It has been shown that early reapplication or use of very high SPF (70–100) may partly compensate for the discrepancy between the amounts of sunscreen applied during testing and in reality, and that sunscreen application can be improved by education of consumers. Missing areas and ultraviolet radiation exposure before sunscreen application are other pitfalls that reduce the protective effect of sunscreens considerably. Current sunscreen labelling overrates the protective effect of a given sunscreen when the reality of sunscreen use is taken into account. This may possibly mislead consumers to feel it is safe to extend sun exposure. Alternatively to educating people to use large amounts of sunscreen, we suggest a simple teaching strategy: (1) Apply before sun exposure and (2) Reapply once within 1 h.     

Effect of daily versus intermittent sunscreen application on solar simulated UV radiation-induced skin response in humans

BACKGROUND: Acute and chronic skin damage occurs as a consequence of solar UV radiation exposure. To diminish such skin damage, the dermatologic community advocates the daily use of sunscreens as part of a sun avoidance strategy. OBJECTIVE: We determined the effectiveness of a sunscreen product with a sunscreen protection factor (SPF) of 15 applied daily in preventing UV-induced histologic damage in human skin compared with the protection afforded by sunscreens with equal or higher SPF applied intermittently. METHODS: Twenty-four subjects were exposed to 2 minimal erythema doses of solar-simulated UV on 4 consecutive days. Three sunscreen products were applied to the buttock of each subject. One SPF 15 product was applied daily before exposure to UV and, to simulate intermittent product use, an SPF 15 or SPF 29 product was applied on 3 of 4 days, with one missed application on days 2, 3, or 4. Skin biopsy specimens were taken and processed for routine and immunohistochemical staining. Changes in number of sunburn cells and Langerhans cells as well as degree of inflammatory infiltrate and lysozyme immunostaining were determined. RESULTS: There was a statistically significant increase in the number of sunburn cells, degree of inflammation, and intensity of lysozyme staining, and there was a decrease in the number of Langerhans cells at sites where sunscreen application was missed as compared with unirradiated control and daily SPF 15 sunscreen-treated sites. CONCLUSION: Our data suggest that daily use of a sunscreen reduces the skin damage produced by UV exposure compared with intermittent use of equal or higher SPF products. The daily application of sunscreens in appropriate quantities reduces the harmful effects of solar UV radiation on skin. Compliance is essential for maximal benefit of sunscreens.     

Randomized controlled trial testing the impact of high-protection sunscreens on sun-exposure behavior

OBJECTIVE: High-protection sunscreens have been suspected to prompt people to increase sun exposure, and thus to increase skin cancer risk. We tested the influence of both the actual protection (sun protection factor [SPF]) and the information about protection (label) on sun-exposure behavior. DESIGN: Randomized controlled trial. SETTING: Four French seaside resorts during summer 2001. PARTICIPANTS: A total of 367 healthy subjects during their 1-week holiday. Outcome was assessable in 98% of them. INTERVENTION: Subjects were offered free sunscreens, with randomization into the following study arms: (1) SPF 40 labeled as "high protection"; (2) SPF 40 labeled as "basic protection"; and (3) SPF 12 labeled as "basic protection." Arm 4, ie, SPF 12 labeled as "high protection," was not implemented for ethical reasons. Subjects were not aware of the real target of the study and were blinded to the SPF value. MAIN OUTCOME MEASURE: Duration of sunbathing exposure during 1 week. Secondary outcomes were occurrence of sunburns and amount of sunscreen used. Influences of SPF and label were assessed separately. RESULTS: Compared with the low-SPF group, the high-SPF group did not have longer sunbathing exposure (12.9 +/- 7.2 h/wk for high SPF vs 14.6 +/- 6.7 h/wk for low SPF; P = .06), experienced fewer sunburns (14% vs 24%; P = .049), and used less sunscreen (median, 30 g vs 109 g; P<.001). The label "high protection" or "basic protection" had no influence on these end points. CONCLUSIONS: In this adult population, higher SPF had no influence on duration of sun exposure and offered better protection against sunburns. Although higher SPF may increase sun exposure duration in specific populations, this effect cannot be viewed as a universal side effect of high-SPF sunscreens.     

Photoprotection in teenagers

BACKGROUND: It is very common to apply a 'template photoprotection' without taking into consideration the background of a specific population. In Lebanon, so far, no preliminary survey has been conducted before launching an educational photoprotection campaign, revealing the need of the people according to their background. MATERIALS AND METHODS: In April 2004, a specific questionnaire was administered to 940 adolescents, aged from 14 to 18 years. The questionnaire comprised 18 multiple-choice questions that established the approximate phototype of teenagers, awareness of ultraviolet (UV) hazard, presence of sufficient information regarding the risk of sun exposure (school, doctor, media) and the use of measures of photoprotection (clothes, sunscreens). RESULTS: The incidence of sunburn in teenagers was high (85.42%) despite their awareness of the risks of unprotected sun exposure. The information regarding sun damage seems to be insufficiently delivered at school and by doctors. The main source of information was television. It was obvious that our adolescents underestimated the value of clothing to protect themselves. The use of clothing comes at the second place after sunscreens. However, the application of sunscreen seems to be inadequate. CONCLUSIONS: While solar protection has become part of routine beach behavior for adolescents, there is room for improvement with better application of sunscreen and more use of clothing, especially wearing hats, and seeking shade. However, it is difficult to appreciate the impact of publicity campaigns on the risks of sun exposure in reducing the incidence of melanoma.     

Do people who apply sunscreens,re-apply them?

Little is known about Australians' practices regarding sunscreen re-application, yet it is routinely advised and has recently been shown to increase the protective efficacy of sunscreens. A baseline survey of sunscreen application and re-application behaviour was therefore conducted in a Queensland community using a standard self-administered questionnaire. Other sun protection methods were also assessed. Of a total of 669 adult respondents, 76% reported using sunscreen and of those, 61% reported re-applying sunscreen. Significantly more women (66%) than men (55%) reported re-applying sunscreen and re-application was inversely related to age (79% of those aged less than 45, 57% of those 45-59 years old and 46% of those over 60 years). Increased rates of re-application were reported during times of increased sun exposure, as well as by those with greater knowledge of the benefits of sunscreen re-application. A recent personal history of non-melanoma skin cancer did not lead to improved rates of sunscreen application, sunscreen re-application, or most forms of physical sun protection.     

Sunscreen protection against cis-urocanic acid production in human skin

Commercial sunscreens may offer some protection from immunosuppression induced by ultraviolet (UV) radiation, but agreement concerning the degree of protection is lacking. Cis-urocanic acid, formed by the photoisomerization of transurocanic acid is considered an important mediator of the cutaneous immunomodulation resulting from exposure to UV radiation. We investigated the effect of sunscreens on the isomerization of urocanic acid in 17 human subjects. Two sunscreens containing chemical filters, sun protection factor (SPF) 4 and SPF 10, and a SPF 10 sunscreen with a physical filter were applied at a thickness of 2 mg/cm2. The effect of a thin layer (0.5 mg/cm2) of the chemical SPF 10 sunscreen was also evaluated, as the amount of sunscreen applied in practice may be considerably less than recommended. All areas were irradiated with a single UV dose of 3.6 SED (standard erythema doses). In irradiated unprotected skin the median net production of cis-urocanic acid was 52% (relative amount). In the sites treated with the chemical sunscreens, the production of cis-urocanic acid was 7.4% (SPF 4) and 3.5% (SPF 10), and isomerization was thus reduced more efficiently at a higher SPF (p<0.01). The physical sunscreen reduced the formation of cis-UCA to 15%, and was significantly less effective than both the chemical SPF 10 sunscreen (p<0.01) and the SPF 4 sunscreen (p<0.01). The production of cis-urocanic acid in the area treated with the thin layer of the chemical SPF 10 sunscreen was 22%. The protection against the production of cis-urocanic acid was therefore reduced significantly (p<0.01) when the sunscreen was applied in an amount lower than recommended.     

Sunscreens

Promoting sunscreen use is an integral part of prevention programmes aimed at reducing ultraviolet (UV) radiation-induced skin damage and skin cancers. Protection against both UVB and UVA radiation is advocated. Most sunscreens combine chemical UV absorbing sunscreens and physical inorganic sunscreens, which reflect UV, to provide broad-spectrum protection. Newer triazole and camphor-derivative based sunscreens, also provide broad-spectrum protection and are more cosmetically acceptable than many traditional agents. Currently licensed sunscreen ingredients in common use rarely cause allergic or photoallergic reactions. Vitamin D levels are not significantly affected by regular use of a sunscreen. Sunscreen use reduces both the development of precancerous solar keratosis and the recurrence of squamous cell carcinomas. Sunscreen use early in life may be important in prevention of basal cell carcinomas. Increased melanoma risk is influenced by the behaviour patterns of regular sunscreen users, as opposed to any direct effect of sunscreens. Sun protection factor (SPF) is affected by application density, water resistance and other factors. An adequate SPF for an individual should be balanced to skin phenotype and exposure habits. The correct use of sunscreens should be combined with the avoidance of midday sun and the wearing of protective clothing and glasses, as part of an overall sun protection regimen.     

Physicians involved in the care of patients with high risk of skin cancer should be trained regarding sun protection measures: evidence from a cross sectional study

Background Knowledge, regarding sun protection, is essential to change behaviour and to reduce sun exposure of patients at risk for skin cancer. Patient education regarding appropriate or sun protection measures, is a priority to reduce skin cancer incidence. Objective The aim of this study was to evaluate the knowledge about sun protection and the recommendations given in a population of non‐dermatologists physicians involved in the care of patients at high risk of skin cancer. Materials and methods This study is a cross‐sectional study. Physicians were e‐mailed an anonymous questionnaire evaluating the knowledge about risk factors for skin cancer, sun protection and about the role of the physician in providing sun protection recommendations. Results Of the responders, 71.4% considered that the risk of skin cancer of their patients was increased when compared with the general population. All the responders knew that UV‐radiations can contribute to induce skin cancers and 71.4% of them declared having adequate knowledge about sun protection measures. A proportion of 64.2% of them declared that they were able to give sun protection advices: using sunscreens (97.8%), wearing covering clothes (95.5%), performing regular medical skin examination (91.1%), to avoid direct sunlight exposure (77.8%), avoiding outdoor activities in the hottest midday hours (73.3%) and practising progressive exposure (44.4%). Conclusion Non‐dermatologist physicians reported a correct knowledge of UV‐induced skin cancer risk factors. The majority of responders displayed adequate knowledge of sun protection measures and declared providing patients with sun protection recommendation on a regular basis. Several errors persisted.     

Attitudes and perceptions regarding skin cancer and sun protection behaviour in an Irish population

BACKGROUND: Although people seem to be well educated on the harmful effects of the sun, they continue to intentionally expose themselves without adequate protection. AIMS: To ascertain baseline knowledge regarding skin cancer and review the sun protection behaviours in an Irish population and the effect of doctor-based education on these behaviours. METHODS: Two hundred participants were recruited for a questionnaire-based study on their perceptions regarding skin cancer and their sun protection behaviour. They were divided into two groups, with one group receiving doctor-based education following the initial survey, and a follow-up questionnaire was carried out within 3 months. RESULTS: Ninety per cent of participants knew that sun exposure was the major risk factor for skin cancer, and 95% knew that sun beds were not a safe way to tan. Despite this, < 20% used regular sunscreen, and 30% had used or were currently using sun beds in order to tan. CONCLUSION: Our study indicated that although the participants' knowledge of skin cancer and risk of sun exposure is high, their sun-protective attitudes were not influenced by education in the clinical setting.     

Relationship between sun‐protection factor and application thickness in high‐performance sunscreen: double application of sunscreen is recommended

Background. High‐performance sunscreen protects both healthy consumers and photosensitive patients from strong ultraviolet (UV) exposure. The sun‐protection factor (SPF), which indicates the efficacy of UV protection, is determined using a prescribed sunscreen application thickness of 2.0 mg/cm². Therefore, users should apply at least 2.0 mg/cm² of sunscreen to obtain the level of UV protection expected from a product. In most cases, however, users apply insufficient amounts of sunscreen. Aim. To determine the amount of sunscreen applied under specific conditions, and the relationship between application thickness and SPF value in high‐performance sunscreen. Methods. The amount of applied sunscreen was calculated under practical conditions and conditions that directed a double application. The SPF values of high‐performance sunscreen applied at three thicknesses (2.0, 1.0 and 0.5 mg/cm²) were determined according to the international SPF testing method. Results. The relationship between SPF value and application thickness correlated in a logarithmic curve. The mean application thickness under practical conditions was approximately 1 mg/cm², and directing subjects to use a double application increased the application thickness to nearly 2 mg/cm². Conclusion. Encouraging a double application of sunscreen will help users apply products at a thickness sufficient to achieve expected SPF efficacy. We recommend that guidance on double application of sunscreen should be posted in public locations where sunscreen is likely to be in use.     

Randomized trial of the impact of a sun safety program on volunteers in outdoor venues

Background: A suitable sun safety educational program could help the public avoid sun exposure‐induced skin damage. The objective of this study was to assess the impact of a sun safety program on volunteers in outdoor venues and explore the most effective sun safety education method in China. Methods: An intervention program was implemented to raise knowledge and behavior regarding sun exposure among volunteers in the outdoor competition venues in Beijing, China. Five intervention methods were used, including class education, free sunscreen samples, pamphlets, posters, and newsletters. The self‐administered multiple‐choice questionnaires were administered before and after the intervention. Results: Two hundred and eighty‐five subjects were enrolled, including 107 males (37.5%) and 178 females (62.5%). The intervention group showed improvement in sun safety knowledge and behavior. Other improvements were achieved in the field of sun safety awareness and intended behavior, with most of the items achieving no statistically significant differences. Subgroup A (multi‐component interventions, including class education, free sunscreen samples, and written materials) achieved better results than subgroup B (written materials only) to improve sun safety knowledge and awareness. Conclusion: Sun safety education could improve volunteer 's sun safety knowledge and behavior in the outdoor venues in China. Multi‐component interventions proved to be the most effective sun safety education method.     

Sun protection factor persistence on human skin during a day without physical activity or ultraviolet exposure

Background/purpose: Recently, we showed that the sun protection factor (SPF) decreases by a constant factor to reach 55% during a day with activities. Organic sunscreens but not inorganic ones are absorbed through the skin. We wished to determine the SPF decrease caused by absorption by investigating the difference in SPF decreases between an organic and an inorganic sunscreen, assuming that the sunscreens are stable, and that the SPF decrease is time dependent if caused by absorption.
Methods: Sunscreens were used on the backs of 22 participants, who were physically inactive at 22 °C. SPF testing was performed 30 min, 4, and 8 h after application of 2 mg/cm² sunscreen. Whether cream evaporation changed the ultraviolet (UV) transmission was studied in vitro .
Results: The SPFs of the organic and inorganic sunscreens were reduced by about 25% after 8 h. Evaporation of the cream did not cause a change in UV transmission in vitro .
Conclusion: A similar decrease in SPF of the organic and inorganic sunscreen was seen during 8 h without activities, and is thus not likely to be caused by absorption or evaporation from the skin. The SPF decrease after 8 h is about 55% when the participants perform activities and 25% without activities.
Trial registration: Registered at http://www.clinicaltrials.gov . Register name: 'Sunscreen: Persistence of Sun Protection Factor and the Influence on Vitamin D'. Register number H-B-2007-120.     

Sun protection factors: world wide confusion

The Sun Protection Factor (SPF) is a very popular instrument in the marketing of sunscreens. Unfortunately it is often not understood how sunscreens work and where the limitations of the SPF are. A lot of aspects of the SPF are confusing, e.g. the race for higher and higher numbers, the effect on SPF when less sunscreen is applied and if sunscreen should be used at all because they may block the Vitamin D synthesis. All this has a negative impact on compliance by the consumer or patient which is the most important influence factor in sun protection. This paper explains how sunscreens work, how the SPF is determined and where the limitations of the current methods exist. The dynamic view of 'UV radiation applied' and the 'UV dose transmitted' through the sunscreen onto the skin as well as onto a substrate in vitro help in the understanding and are also promising approaches in the in vitro assessment. A variation of the in vitro assessment of a sunscreen is the in silico calculation based on the absorption spectrum of the UV filters and an assumption about the irregular sunscreen film on the skin. The sunscreen simulator program can be used to determine how the SPF is affected by applying smaller amounts of sunscreen. Besides the SPF, UVA protection is also discussed. The degree of UVA protection determines the quality of the overall UV protection, whereas the SPF is an indication of the quantity of protection. Furthermore other protection factors such as IPF, iSPF, RSF and p53, and the inhibition of the Vitamin D3 synthesis by sunscreens are also discussed. In conclusion it is shown that the accuracy and robustness of the SPF and other Protection Factors will improve significantly with the availability of true broad-spectrum sunscreens rather than conventional UVB-biased sunscreens, because uniform protection profiles lead to protection independent of the action spectrum of the endpoint and the UV-radiation source.     

Sunscreen ingredients and labelling: a survey of products available in the UK

BACKGROUND: In Europe, where sunscreens are classified as cosmetics, products may contain one or several of 27 permitted 'ultraviolet filters'. We were unable to find published data on the frequency of usage of individual ultraviolet (UV)-absorbing chemicals in currently available sunscreens. AIM: To record the active ingredients and labelling characteristics of sunscreens available in the UK. METHODS: In 2005, two dermatologists visited seven retail outlets, which stocked a large range of sunscreens. Manufacturers were also contacted. For each product, the names of UV-protective ingredients and the labelling information, including sun protection factor (SPF), UVA protection and age group for which the product was marketed were recorded. RESULTS: Data on 308 skin sunscreen products and 21 lip sunscreens were recorded. For skin products, the SPF ranged from 2 to 60. In total, 23 different UV-absorbing ingredients were found, 4 of which were found in > 25% of products. The child and baby skin sunscreens (n = 52) had a significantly higher median SPF of 40, compared with 15 for the remaining 256 adult products (P < 0.001). The number of UV-absorbing chemicals and the frequency of those commonly used did not differ substantially between child and adult products. Of skin sunscreens marketed for babies, 60% contained 2-6 UV-absorbing chemicals. Nearly half of the skin sunscreens contained at least one of nine UV-absorbing chemicals not available in patch testing formulations from commercial suppliers. CONCLUSIONS: The results of this survey indicate current sunscreen content and labelling, and are a benchmark from which new developments can be tracked. More standard sunscreen labelling, particularly separate listing of active ingredients, would be helpful. It was surprising to find UV-absorbing chemicals in products sold for use on babies.     

Sun exposure behavior and protection practices in a Mediterranean population: a questionnaire-based study

Objective: Skin cancer campaigns have only recently been implemented in a wide scale in Greece. In order to better target those individuals at risk, we aimed to explore sun exposure behaviors in a sample of the Greek population.
Methods: A total of 802 subjects, randomly selected among the residents of the two largest Greek cities, underwent a questionnaire-based telephone interview, assessing the degree of sun exposure patterns and knowledge of skin cancer risk factors.
Results: Females more commonly (90%) used sunscreens compared with males (67.5%), and among sunscreen users, only 8% used products with SPF <10. Almost half of the participants (48%) preferred going to the beach during the midday hours. Over exposure to the sun was mostly reported by individuals with phototypes III/IV and of younger age (18–35 years). Most participants were aware of sun exposure as a cause of skin cancer, but among those who did not, 41% were younger than 34 years of age.
Conclusions: In our survey, significant differences in age, sex and phototypes were observed with regard to sun exposure patterns and sunscreen use. Educational campaigns should focus more on younger age groups, encouraging a more complete set of photoprotective measures. However, potential trial limitations inherent in self-reported measures should be taken into account.     

会宁县中学生对紫外线危害认知和防护措施的调查简

目的调查会宁县中学生对紫外线危害的知晓情况、防晒意识、防护方式及获取途径,为预防紫外线损伤提供科学依据。方法以问卷调查形式,了解会宁县中学生对有关紫外线引起皮肤损害、采取的防护措施及防晒知识的获取途径。结果共有300人完成问卷调查,大部分中学生知道紫外线照射可导致皮肤损伤,38.83%和51.20%的学生知道长期过度紫外线照射可致皮肤肿瘤和光老化;61.86%中学生在进行户外活动时采取防护措施,涂防晒霜的占32.78%,女生和城市生源中学生在防护意识和使用防晒霜方面的比例高于男生和农村生源（P〈0.05）;电视传媒是中学生获取防晒知识的主要途径。结论会宁县中学生对有关紫外线引起皮肤危害的认知及防护知识认知度低,需要加强紫外线危害与防护知识的宣传和教育。     

Fotoprotección

—Sun protection is aimed at preventing damage to our skin as the result of its exposure to solar ultraviolet radiation. The skin has some mechanisms to protect itself from this harm, whose efficacy varies from one person to the next and is clearly insufficient in fair-skinned people.Current approaches to photoprotection focus on reducing overall exposure to sunlight, especially during peak sun hours; this includes wearing protective clothing, hats and sunglasses and regular use of broad-spectrum high SPF sunscreen (SPF 15 or higher). Using sunscreen is the most common practice for protecting the skin from the sun, although it is the most controversial.This review summarizes the different approaches to sun protection, with special reference to sunscreens, either oral or topical: their types, main characteristics, side effects, controversies and mechanisms of failure.Moreover, Public Health Guidelines and Recommendations from the International Agency for Research on Cancer are presented. Public education on sun protection must be aimed at multiple and diverse target populations and activities. Childhood interventions are very important, not only because behavioural changes are easier in children than adults, but also because ultraviolet damage is cumulative and sun protection strategies should start early in life.