PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of nihpaAbout Author manuscriptsSubmit a manuscriptHHS Public Access; Author Manuscript; Accepted for publication in peer reviewed journal;
 
J Am Acad Dermatol. Author manuscript; available in PMC 2013 January 1.
Published in final edited form as:
PMCID: PMC3193866
NIHMSID: NIHMS258222

Compliance with Sunscreen Advice in a Survey of Adults Engaged in Outdoor Winter Recreation at High Elevation Ski Areas

Abstract

Background

Adults are advised to wear sunscreen with a sun protection factor of 15+, apply it up to 30 minutes prior to sun exposure, and reapply it after two hours to reduce exposure to ultraviolet (UV) radiation in sunlight for the prevention of skin cancer.

Objective

This study investigated the extent to which adults comply with sunscreen advice.

Methods

A survey was conducted with 4,837 adult skiers and snowboarders at 28 high-altitude ski areas in Western North America in January – April 2001-02. Respondents self reported use of sunscreen, its SPF, time of first application, and reapplication.

Results

Only 4.4% (95% CI=±0.6) of adults were in full compliance with all sunscreen advice. Half (49.8% [95% CI=±1.4]) complied with SPF 15+ advice. Of those wearing sunscreen, 73.2% (95% CI=±1.8) applied the sunscreen 30 minutes before beginning skiing/snowboarding, but only 20.4% (95% CI=±2.0) complied with advice to reapply it after 2 hours. Total compliance was lowest during inclement weather, on low-UV days, by males, and among respondents who believed skin cancer was unimportant and with low sun sensitive skin. It was positively associated with wearing lip balm and hats with a brim.

Limitations

The sample was predominantly male and of high socio-economic status; the results apply most to winter recreation when UV radiation levels are low, and sunscreen use was assessed by self-report.

Conclusion

While the recommendation to use SPF 15+ sunscreen has reached many adults, the reapplication advice is heeded by few adults and needs to be highlighted in future sun safety promotions.

Keywords: sunscreen, sunscreen reapplication, adults, outdoor recreation, sun protection, ultraviolet radiation

Introduction

Sunscreen appears to be effective at reducing squamous cell carcinoma.1, 2 It also may reduce benign melanocytic nevi and solar keratoses, risk factors associated with skin cancer development.3-7 A recent analysis indicated that sunscreen was a cost effective preventive measure.8

To obtain its maximum protection, sunscreens should have a high sun protection factor (SPF), be applied before going into the sun, and be reapplied.9, 10 A minimum SPF of 15 is recommended and higher SPF should be considered when outside for extended periods or when UV radiation is extremely high. Some sunscreens need a short period of time (20-30 minutes) to be absorbed and become effective, 9, 11, 12 so, as a general rule, individuals are advised to apply sunscreen up to 30 minutes before going outdoors. Sunscreens need to be reapplied to compensate for initial under-application of sunscreen13-15 and to insure they stay effective when exposed to moisture or rubbing with sand or fabric.12, 16-18 With a few exceptions, the most commonly recommended reapplication interval is every 2-3 hours.9, 12 Given the published rates of sunburning among adults, however, it seems prudent and reasonable to assume that many individuals ignore part or all of the recommendations.19

Analyses are reported describing patterns of compliance with sunscreen advice in a sample of adults at ski areas in Western North America. UV levels can be dangerously high at ski areas, especially during the spring,20 because many ski areas are at high elevation and snow reflects substantial UV.21-26 Sunscreen is a valuable prevention strategy during skiing and snowboarding. Sun exposure is incidental to this winter recreation and length of sun exposure is dictated by factors other than a desire to tan, such as the ski area’s hours of operation. Hence, sunscreen will likely reduce rather than prolong UV exposure.

Methods

Respondents

Respondents (n=4,837 adults) were interviewed while visiting 28 ski areas in the western United States and Canada in January to April 2001 (n=2,991; 99.3% completion rate; 0.7% refused [n=23]) and January to March 2002 (n=1,846; 99.0% completion rate; 1.0% refused [n=24]). A total of 306 guests (n=203 in 2001; 103 in 2002) approached were ineligible – under age 18 (n=48), employed at the ski area (n=175), previously interviewed (n=70), or could not speak English (n=13). Also 306 guests (n=203 in 2001; 103 in 2002) were approached but deemed ineligible and not interviewed – under age 18 (n=48), employed at the ski area (n=175), previously interviewed (n=70), or could not speak English (n=13).

Ski areas were located in Alaska, California, Colorado, Idaho, Montana, New Mexico, Nevada, Oregon, and Utah in the United States, and in British Columbia in Canada. Areas varied in size, management and ownership structure, lift ticket prices, and guest demographics. UV measured during data collection using handheld Optix Tech SunSafe meters ranged up to a UV Index of 10 (direct UV Index M=2.68, sd=2.21).27 All ski areas were members of the National Ski Area Association (NSAA) and had at least two aerial chairlifts. A description of ski area selection and recruitment was published previously.28

The ski areas were participating in a trial to evaluate a sun protection education program designed primarily for employees but also conveyed to guests.28-30 Respondents included in the present analysis were guests visiting the ski areas either prior to randomization of ski areas to experimental condition (i.e., n=2,991 in baseline season in 2001) or at ski areas assigned to the control condition during the posttesting season (n=1,846 in 2002). Both samples were cross-sectional. Guests at ski areas interviewed assigned to the intervention condition (n=1679 in 2002) were not included because they could have been exposed to the intervention that altered their sunscreen use. Ski area employees were not analyzed because they spend more days at the ski areas and a large amount of their time outdoors occurs when working, not recreating, compared with guests.

Interview Procedures

Respondents were interviewed face-to-face by trained interviewers while riding on chair lifts (and gondolas). Chair lifts had a minimum run time of four minutes. Interviews occurred during three-day periods (one weekend day and two weekdays). Ski areas were visited during the same week of the winter season in both 2001 and 2002. Interviewers completed 12 – 20 surveys per day and the number of respondents interviewed at each area ranged from 52 to 359 respondents. Interviews were attempted on all eligible chair lifts; however, main chair lifts providing access to large parts of the mountain were over-sampled.

Interviewers boarded the chair lifts with potential respondents, taking the outside of the seat if possible. They introduced the survey to respondents, reading a consent statement. Interviewers recruited the person seated immediately next to them for the survey (if seated in the middle, the person to the right). If the respondent refused or was ineligible, another potential respondent on the chair was recruited. Only one interview was completed per chair lift ride. Responses to the 4-minute interview were recorded in a survey booklet. All protocols for this project were reviewed by the Institutional Review Boards (IRBs) at the institutions where the investigators were employed at the time of the study – AMC Cancer Research Center, California State University, Chico, San Diego State University, and University of Colorado Denver. These IRBs approved the project as “exempt” under CFR 46.101(b)(2).

Measures

The questionnaire contained measures of sunscreen compliance developed by the investigators and reviewed for face validity. The survey was pilot tested for feasibility with adult skiers and snowboarders in a previous study.31 Current sunscreen use was measured with four questions: “Are you wearing sunscreen on your skin today, or not” (yes/no) and if yes, “what is the SPF of that sunscreen” (number), “at what time did you first put on that sunscreen” (hour:minute), and “have you reapplied the sunscreen today” (yes/no). Respondents were also asked the time they started skiing or snowboarding that day (hour:minute) which served as a proxy measure for the time they first went outdoors in the sun. Interviewers recorded the time of the interview (hour:minute).

These data were used to create dichotomous measures (yes/no) of compliance with three sunscreen recommendations. Respondents who reported wearing sunscreen with an SPF of 15 or more were considered “compliant” with the first criterion of the recommended protocol. (SPF 15+ when outdoors). Respondents who reported that the time they first applied sunscreen was 30 minutes prior to the time they started skiing/snowboarding that day were “compliant” with the second criterion to apply sunscreen before going outdoors. Finally, respondents who were interviewed 2 hours or more after the time that they first applied sunscreen and reported that they had reapplied sunscreen were “compliant” with the reapplication criterion. Respondents who were interviewed within two hours of first applying sunscreen were assigned missing values for compliance with reapplication advice, as it did not yet apply to them. Each respondent was assigned a total compliance score, which was given a value of 1 if the respondent reported wearing sunscreen with SPF of at least 15, applied sunscreen more than 30 minutes before started skiing, and reapplied sunscreen (unless interview time was less than 2 hours after starting, then the total compliance score was assigned a missing value).

A series of questions were included to assess potential predictors of sunscreen compliance. These included respondents’ history of sunburns while skiing/snowboarding this season and at any time in the past (yes/no), contemporaneous use of other sun protection (self-report of sunscreen lip balm use [yes/no] and its SPF; observed head, ear, face, and neck covering [yes/no] and sunglass/goggle use [yes/no]), perceived self-efficacy for sun protection and importance of skin cancer (5-point Likert scales), skin sun sensitivity (always burn and is unable to tan/usually burns but can tan if I work at it/sometimes mildly burns and then tans easily/rarely burns and tans easily), observed gender, self-reported age, self-reported education level, and observed equipment (ski/snowboard). In addition, three predictor indices were created. A skill index was calculated by summing z-scores for the respondents’ self-reported snow sport expertise (beginner/intermediate/expert) and days reported skiing/boarding during the current season. A weather index was created by summing z-scores for observed cloud cover (clear/partly cloudy/cloudy), precipitation (none/flurries or light snow/heavy snow or other), and wind (calm/light/moderate/strong). Finally, a UV intensity index was developed by summing z-scores for days since the winter solstice, ski area latitude, and altitude at ski area base.

Statistical Analysis

Respondent characteristics and sunscreen compliance patterns are reported as percentages. Statistical tests of the association between sunscreen use and potential predictors were performed in separate multiple regression models. In the regressions, each outcome variable was modeled against all predictor variables using SAS PROC MIXED with a random ski area effect. Non-significant variables were removed and reduced models were run with only the significant predictors. Regression parameters are reported for continuous predictor variables and least square means are reported for categorical variables.

Results

Table 1 describes the characteristics of the adults interviewed. The sample was predominantly male, non-Hispanic white, college educated, and young (67.9% were 45 years of age or younger). This reflects the demographics of the sports of skiing and snowboarding. The sample was comprised of respondents who were predominantly skiers, of intermediate or expert ability, spent more than five days skiing/snowboarding during the season , and lived locally (within 200 miles of the ski area).

Table 1
Respondent Characteristics

Compliance with Sunscreen Advice

Compliance with sunscreen advice was inconsistent (Table 2). Overall, 49.8% (95% CI=±1.4) of adults were compliant with advice to wear sunscreen with SPF 15+. Of these, 73.2% (95% CI=±1.8) complied with advice to apply sunscreen 30 minutes before sun exposure and 20.4% (95% CI=±2.0) complied with advice to reapply it after 2 hours. However, only 4.4% (95% CI=±0.6) of all respondents were in total compliance with sunscreen advice (i.e., complied with all three recommendations). The most common pattern was to wear sunscreen with SPF 15+ and apply it at least 30 minutes before going outdoors (36.0% [95% CI=±1.4]of all respondents), with just 6.3% wearing a sunscreen with SPF 15+ and reapplying it and 4.0% (95% CI=±0.6) only wearing sunscreen with SPF 15+. Almost half of adults (45.6% [95% CI=±1.4]) did not comply with any of these sunscreen recommendations.

Table 2
Response to Sunscreen Compliance Questions

Predictors of Complete Compliance with Sunscreen Advice

Several weather and personal factors predicted whether adults were in complete compliance with the sunscreen advice (Table 3). Complete compliance was lowest during inclement weather, on days with lower UV intensity, by males, among respondents who felt skin cancer was unimportant, and who reported low sun sensitive skin.

Table 3
Results of Multivariate Regression of Total Compliance on Various Predictor Variables

Association of Complete Compliance with Other Sun-Protective Behaviors

Adults who were in complete compliance with sunscreen advice also were likely to practice other sun protection behaviors (Table 3). Specifically, complete compliance with sunscreen advice was higher among those also using sunscreen lip balm (8.0% using lip balm vs. 3.1% not using lip balm, F[1,4011]=54.48, p<.0001) and those wearing a hat with a brim (6.7% using hats vs. 4.4% not using hats, F[1,4011]=6.89, p=0.0087). No other variables were statistically associated with complete compliance at the 0.05 level of significance.

Discussion

Even though half of the respondents followed advice to wear SPF 15+ sunscreen, very few complied with all of the advice that maximizes sunscreen’s efficacy (i.e., apply it before going outdoors and reapply it). Advice to use sunscreen with SPF 15+ has been conveyed through commercial advertising and in public health messages and seems to have been taken to heart by at least half of the winter sports enthusiasts surveyed.

Communication regarding pre-application and reapplication needs to be stressed in future campaigns. The effectiveness of sunscreen, particularly those that are not waterproof or water resistant and bind well with the skin, can degrade over time and result in very little photoprotection.12, 17, 18 Unfortunately, too, many adults under-apply sunscreen15 so reapplication is important to correct this, especially within 30 minutes of initial application.12 Failure to pre-apply and reapply sunscreen means that many of the respondents in this survey may have risked sunburns when spending the entire day outdoors.16, 32

The prevalence of SPF 15+ sunscreen use in this sample was higher than that recorded in general population surveys. Other research has found similar elevated use during recreation and activities that involve prolonged periods of sun exposure (e.g., beachgoing, golfing, gardening).33, 34 Individuals may use sunscreen to prolong the time that it takes to become sunburned when intentionally engaged in sun exposure,9, 19, 34-37 including outdoor recreation. However, sun exposure is incidental in many recreational pursuits, and length of sun exposure is determined by factors other than an intentional desire to obtain a tan. Thus, sunscreen use during such recreation may not prolong time in the sun and instead be a photoprotection strategy that actually reduces overall UV exposure. Also, the sun exposure achieved during recreation should be balanced against its physical and mental benefits.

It was encouraging that nearly 3 in 4 adults who used sunscreen had applied it to the skin at least 30 minutes prior to going outdoors. Compliance with pre-application advice also was far higher in this study than in a study of sunscreen use by Lebanese adolescents at beaches.38 Still, many respondents did not report reapplying sunscreen. Low rates of reapplication were seen in another study (20%-30% depending on the body location).15

The lower compliance with sunscreen advice by males is consistent with their infrequent sun protection behaviors of all type (an exception being hats used by men).15, 19, 33, 34, 38 The lower compliance with sunscreen advice during inclement weather and by adults with less sun sensitive skin, seen elsewhere,15, 33 may indicate that some adults are judging whether to use sunscreen based on environmental or personal cues to their risk.

Implications for Skin Cancer Prevention

The next generation of sun safety promotions needs to move beyond simply recommending the use of sunscreen and to teaching adults how to maximize its effectiveness through pre-application and reapplication. There are several benefits from stressing reapplication. It can help to overcome consumers’ reluctance to initially apply the large amount of sunscreen needed to obtain its full benefit (perhaps because it feels greasy and leaves a film on the skin39). Those who reapply can substantially improve the effectiveness of an initial application of sunscreen.12 Also, stressing reapplication introduces some novelty in the sun safety messages compared to repeating the simple and oft heard message to use sunscreen. Granted, reapplication may not have been necessary in mid-winter (January) or on cloudy days in the winter, when UV radiation levels were low40 in this study, but we found that UV radiation levels measured during “spring skiing” (March and April) at the participating ski areas can be very high.41

In addition, sun protection promotions should stress the use of other forms of protection such as clothing and reducing overall time in the sun, as well as the use of sunscreen, to help achieve a beneficial balance. Decisions to wear head, ear, face, and neck covering in the winter may be done so for warmth protection, which may explain why they did not associate with sunscreen compliance.

The results also indicate that certain subgroups should be high-priority populations for sunscreen promotion. Men may be less concerned with the appearance and health of their skin, and may consider the use of skin lotions such as sunscreen to be less normative than females. They also may not be as anxious about skin cancer as women. Adults who believe that skin cancer is not an important health concern complied less with sunscreen advice.

Finally, redoubled efforts are needed to teach adults how environmental features affect UV radiation levels.42 Inclement weather (i.e., cloud cover) reduces UV radiation only partially especially when UV radiation levels are high in spring and summer, so depending on inclement weather for sun protection decisions can result in risky sun exposure. Moreover, the high elevation and high reflectivity of the snow surface at ski areas increased UV radiation23-26 and adults should consider taking precautions even in winter months.

Strengths and Weaknesses of the Study

There are several strengths and limitations to this analysis of sunscreen compliance. The large sample provided substantial statistical power and the 28 ski areas in nine states/provinces and two countries increased the potential generalizability of the findings. While ski areas were located only in Western North America, respondents lived in all part of North America and in countries outside the United States and Canada. Still, the analysis is most applicable to outdoor recreation enthusiasts that are male and of high socio-economic status. The sample was almost entirely non-Hispanic white but this is the highest risk population for skin cancer.43 The results apply most to winter recreation, a time when UV radiation levels are low (although it UV can be high and sufficient to sunburn21, 44) and large portions of the skin are covered. Vitamin D levels can drop in the winter, raising concern about recommending sun protection. However, several studies on sunscreen use in practice (rather than in controlled clinical measurement) found little evidence of reduced vitamin D levels.45-49 Dietary supplementation may be the best way to maintain vitamin D levels in winter.50, 51 Another strength is that participants were asked to recall use of sunscreen on the day of the interview rather than at some time in the past which should have reduced memory errors. Still, these were self-reports and subject to social desirability biases and demand effects. Also, the measure did not determine whether adults selected the SPF in their sunscreen by choice or availability (few low SPF sunscreen are available). Fortunately, measures of other sun protection behaviors were obtained through observation which is less subject to recall errors and such biases. A final limitation is the age of the data, collected nearly a decade ago. Since then, information on the health benefits of vitamin D and concerns about the quality of, and chemical in, sunscreens have been in the news, which may have reduced adults’ compliance with sunscreen advice.

Future Research

The results suggest several additional avenues of inquiry. This analysis of compliance with sunscreen advice needs to be replicated with adults in summertime settings and with children and adolescents. The inclement weather during winter requires more clothing and this may explain why so many adults applied sunscreen before going outdoors.40 Frequent compliance with pre-application advice may not occur in summer where it is easier to apply outdoors when more skin is exposed. It would be useful to determine whether these compliance patterns occur in other outdoor venues and during other outdoor activities, or among a broader sample of at-risk adults who are perhaps older and less interested in physical recreation, or live outside North America. Similarly, it would be instructive to determine which forms of sun protection promotion achieves complete compliance with sunscreen advice, e.g., public health campaigns, advice from clinicians, or social pressure from family and friends. These results should be compared to locations where promotions have been more intensive such as Australia to see whether complete compliance can be elevated. Finally, the association of sunscreen lip balm use with complete compliance needs further exploration. It may be that these products are frequently recommended together and considered by many adults to be part of the general sunscreen advice. Alternatively, the concomitant use of these two products, along with hats with a brim, indicated that there is a group of highly sun safe individuals who have internalized the entire sun protection protocol. If so, they should be described and the means by which their full was achieved investigated to provide insights into effective sun protection promotions.

Capsule Summary

  • Adults should wear sunscreen with sun protection factor (SPF) of 15+, apply it before going outside, and reapply it after two hours.
  • Half (49.8%) of adult skiers and snowboarders interviewed at North American ski areas complied with advice to wear sunscreen with SPF 15+ and 73.2% of sunscreen wearers applied it before going outside. Only 20.4% reapplied sunscreen. Almost no one (4.4%) followed the advice completely.
  • Adults need to be convinced to follow sunscreen advice.

Acknowledgments

Funding source: This project was funded by grants from the National Cancer Institute (CA81028 and CA104876). Dr. Buller and Ms. Maloy received salary support from Klein Buendel, Inc. The sponsor did not participate in the project. The design, conduct of the study, interpretation of the data, and preparation, review and approval of the manuscript was performed solely by the authors.

Footnotes

Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Conflict of interest statement: The authors have no conflict of interest to declare.

Contributor Information

David B. Buller, Klein Buendel, Inc., Golden, CO.

Peter A. Andersen, San Diego State University, San Diego, CA.

Barbara J. Walkosz, University of Colorado Denver, Denver, CO.

Michael D. Scott, Mikonics, Inc., Auburn, CA.

Julie A. Maloy, Klein Buendel, Inc., Golden, CO.

Mark B. Dignan, University of Kentucky, Lexington, KY.

Gary R. Cutter, University of Alabama, Birmingham, AL.

Reference List

(1) Green A, Williams G, Neale R, Hart V, Leslie D, Parsons P, et al. Daily sunscreen application and betacarotene supplementation in prevention of basal-cell and squamous-cell carcinomas of the skin: a randomised controlled trial. Lancet. 1999 Aug 28;354(9180):723–9. [PubMed]
(2) van der Pols JC, Williams GM, Pandeya N, Logan V, Green AC. Prolonged prevention of squamous cell carcinoma of the skin by regular sunscreen use. Cancer Epidemiol Biomarkers Prev. 2006 Dec;15(12):2546–8. [PubMed]
(3) Gallagher RP, Rivers JK, Lee TK, Bajdik CD, McLean DI, Coldman AJ. Broad-spectrum sunscreen use and the development of new nevi in white children: A randomized controlled trial. JAMA. 2000 Jun 14;283(22):2955–60. [PubMed]
(4) Thompson SC, Jolley D, Marks R. Reduction of solar keratoses by regular sunscreen use. N Engl J Med. 1993 Oct 14;329(16):1147–51. [PubMed]
(5) Naylor MF, Boyd A, Smith DW, Cameron GS, Hubbard D, Neldner KH. High sun protection factor sunscreens in the suppression of actinic neoplasia. Arch Dermatol. 1995 Feb;131(2):170–5. [PubMed]
(6) Darlington S, Williams G, Neale R, Frost C, Green A. A randomized controlled trial to assess sunscreen application and beta carotene supplementation in the prevention of solar keratoses. Arch Dermatol. 2003 Apr;139(4):451–5. [PubMed]
(7) Green A, Battistutta D, Hart V, Leslie D, Weedon D. Skin cancer in a subtropical Australian population: incidence and lack of association with occupation. The Nambour Study Group. Am J Epidemiol. 1996 Dec 1;144(11):1034–40. [PubMed]
(8) Gordon LG, Scuffham PA, van der Pols JC, McBride P, Williams GM, Green AC. Regular sunscreen use is a cost-effective approach to skin cancer prevention in subtropical settings. J Invest Dermatol. 2009 Dec;129(12):2766–71. [PubMed]
(9) Moloney FJ, Collins S, Murphy GM. Sunscreens: safety, efficacy and appropriate use. Am J Clin Dermatol. 2002;3(3):185–91. [PubMed]
(10) Palm MD, O’Donoghue MN. Update on photoprotection. Dermatol Ther. 2007 Sep;20(5):360–76. [PubMed]
(11) American Cancer Society . Skin cancer prevention and early detection. American Cancer Society, Inc; 2009. [cited 2009 May 19];Available from: www.cancer.org.
(12) Diffey BL. When should sunscreen be reapplied? J Am Acad Dermatol. 2001 Dec;45(6):882–5. [PubMed]
(13) Autier P, Boniol M, Severi G, Dore JF. Quantity of sunscreen used by European students. Br J Dermatol. 2001 Feb;144(2):288–91. [PubMed]
(14) Azurdia RM, Pagliaro JA, Diffey BL, Rhodes LE. Sunscreen application by photosensitive patients is inadequate for protection. Br J Dermatol. 1999 Feb;140(2):255–8. [PubMed]
(15) Neale R, Williams G, Green A. Application patterns among participants randomized to daily sunscreen use in a skin cancer prevention trial. Arch Dermatol. 2002 Oct;138(10):1319–25. [PubMed]
(16) Odio MR, Veres DA, Goodman JJ, Irwin C, Robinson LR, Martinez J, et al. Comparative efficacy of sunscreen reapplication regimens in children exposed to ambient sunlight. Photodermatol Photoimmunol Photomed. 1994 Jun;10(3):118–25. [PubMed]
(17) Stokes RP, Diffey BL. The water resistance of sunscreen and day-care products. Br J Dermatol. 1999 Feb;140(2):259–63. [PubMed]
(18) Stokes RP, Diffey BL. A novel ex vivo technique to assess the sand/rub resistance of sunscreen products. Int J Cosmet Sci. 2000 Oct;22(5):329–34. [PubMed]
(19) Vainio H, Miller AB, Bianchini F. An international evaluation of the cancer-preventive potential of sunscreens. Int J Cancer. 2000 Dec 1;88(5):838–42. [PubMed]
(20) Andersen PA, Buller DB, Walkosz BJ, Scott MD, Maloy JA, Cutter GR, et al. Environmental cues to ultraviolet radiation and personal sun protection in outdoor winter recreation. Archives of Dermatology. 2010;146:1241–7. [PMC free article] [PubMed]
(21) Rigel EG, Lebwohl MG, Rigel AC, Rigel DS. Ultraviolet radiation in alpine skiing: magnitude of exposure and importance of regular protection. Arch Dermatology. 2003 Jan;139(1):60–2. [PubMed]
(22) Andersen PA, Buller DB, Walkosz BJ, Scott MD, Maloy JA, Cutter GR, et al. Environmental cues to ultraviolet radiation and personal sun protection in an outdoor winter recreation. Archives of Dermatology. 2010 In press. [PMC free article] [PubMed]
(23) Blumthaler M, Ambach W, Rehwald W. Solar UV-A and UV-B radiation fluxes at two Alpine stations at difference altitudes. Theoretical and applied climatology. 1992;46:39–44.
(24) Reiter R, Munzert K, Sladovic R. Results of 5-year concurrent recording of global, diffuse, and UV radiation at three levels in the Northern Alps. Archiv für Meteorologie, Geophysik und Bioklimatologie Serie B. 1982;30:1–28.
(25) Blumthaler M, Ambach W. Human ultraviolet radiant exposure in high mountains. Atm Environ. 1988;22:749–53.
(26) Elwood JM, Koh HK. Etiology, epidemiology, risk factors, and public health issues of melanoma. Current Opinion Oncology. 1994 Mar;6(2):179–87. [PubMed]
(27) Andersen PA, Buller DB, Walkosz BJ, Scott MD, Maloy JA, Cutter GR, et al. Environmental cues to ultraviolet radiation and personal sun protection in an outdoor winter recreation. Archives of Dermatology. 2010 In press. [PMC free article] [PubMed]
(28) Buller DB, Andersen PA, Walkosz BJ, Scott MD, Cutter GR, Dignan MB, et al. Randomized trial testing a worksite sun protection program in an outdoor recreation industry. Health Educ Behav. 2005 Aug;32(4):514–35. [PubMed]
(29) Walkosz B, Voeks J, Andersen P, Scott M, Buller D, Cutter G, et al. Randomized trial on sun safety education at ski and snowboard schools in western North America. Pediatr Dermatol. 2007 May;24(3):222–9. [PubMed]
(30) Walkosz BJ, Buller DB, Andersen PA, Scott MD, Dignan MB, Cutter GR, et al. Increasing sun protection in winter outdoor recreation a theory-based health communication program. Am J Prev Med. 2008 Jun;34(6):502–9. [PMC free article] [PubMed]
(31) Buller DB, Andersen PA, Walkosz B. Sun safety behaviours of alpine skiers and snowboarders in the western United States. Cancer Prev Control. 1998 Jun;2(3):133–9. [PubMed]
(32) Pruim B, Wright L, Green A. Do people who apply sunscreens, re-apply them? Australas J Dermatol. 1999 May;40(2):79–82. [PubMed]
(33) Dobbinson S, Jameson K, Francis K. Wakefield. 2006-07 National sun protection Survey. Report 2: Australians’ sun protective behaviours and sunburn incidence on summer weekends, 2006-07 and comparison with 2003-04 in the context of the first national mass media campaign. The Cancer Council Victoria; 2008. Prepared for. Ref Type: Unpublished Work.
(34) Thieden E, Philipsen PA, Sandby-Moller J, Wulf HC. Sunscreen use related to UV exposure, age, sex, and occupation based on personal dosimeter readings and sun-exposure behavior diaries. Arch Dermatol. 2005 Aug;141(8):967–73. [PubMed]
(35) Autier P, Dore JF, Reis AC, Grivegnee A, Ollivaud L, Truchetet F, et al. Sunscreen use and intentional exposure to ultraviolet A and B radiation: a double blind randomized trial using personal dosimeters. Br J Cancer. 2000 Nov;83(9):1243–8. [PMC free article] [PubMed]
(36) Autier P, Boniol M, Dore JF. Sunscreen use and increased duration of intentional sun exposure: still a burning issue. Int J Cancer. 2007 Jul 1;121(1):1–5. [PubMed]
(37) Centers for Disease Control and Prevention . Preventing skin cancer: Findings of the task force on community preventive services on reducing exposure to ultraviolet light. 2003. Report No.: MMWR CDC Surveillance Summ 52. [PubMed]
(38) El Sayed F, Ammoury A, Nakhle F, Dhaybi R, Marguery MC. Photoprotection in teenagers. Photodermatol Photoimmunol Photomed. 2006 Feb;22(1):18–21. [PubMed]
(39) Solky BA, Phillips PK, Christenson LJ, Weaver AL, Roenigk RK, Otley CC. Patient preferences for facial sunscreens: a split-face, randomized, blinded trial. J Am Acad Dermatol. 2007 Jul;57(1):67–72. [PubMed]
(40) Andersen PA, Buller DB, Walkosz B, Maloy J, Cutter G, Scott MD, et al. Testing a theory-based health communication program: A replication of Go Sun Smart in outdoor winter recreation. Journal of Health Communication. 2009 In press. [PMC free article] [PubMed]
(41) Andersen PA, Buller DB, Walkosz BJ, Scott MD, Maloy JA, Cutter GR, et al. Environmental cues to ultraviolet radiation and personal sun protection in an outdoor winter recreation. Archives of Dermatology. 2010 In press. [PMC free article] [PubMed]
(42) Andersen PA, Buller DB, Walkosz BJ, Scott MD, Maloy JA, Cutter GR, et al. Environmental cues to ultraviolet radiation and personal sun protection in an outdoor winter recreation. Archives of Dermatology. 2010 In press. [PMC free article] [PubMed]
(43) U.S.Cancer Statistics Working Group . United States Cancer Statistics: 1999-2004 Incidence and Mortality Web-based Report. U.S. Department Health and Human Services, Centers for Disease Control and Prevention, National Cancer Institute; Atlanta: 2007.
(44) Andersen PA, Buller DB, Walkosz BJ, Scott MD, Maloy JA, Cutter GR, et al. Environmental cues to ultraviolet radiation and personal sun protection in an outdoor winter recreation. Archives of Dermatology. 2010 In press. [PMC free article] [PubMed]
(45) Farrerons J, Barnadas M, Rodriguez J, Renau A, Yoldi B, Lopez-Navidad A, et al. Clinically prescribed sunscreen (sun protection factor 15) does not decrease serum vitamin D concentration sufficiently either to induce changes in parathyroid function or in metabolic markers. Br J Dermatol. 1998 Sep;139(3):422–7. [PubMed]
(46) Farrerons J, Barnadas M, Lopez-Navidad A, Renau A, Rodriguez J, Yoldi B, et al. Sunscreen and risk of osteoporosis in the elderly: a two-year follow-up. Dermatology. 2001;202(1):27–30. [PubMed]
(47) International Agency for Research on Cancer (WHO) Working Group . Vitamin D and cancer. Vol. 5. World Health Organization; Geneva, Switzerland: 2008. Report No.
(48) Marks R, Foley PA, Jolley D, Knight KR, Harrison J, Thompson SC. The effect of regular sunscreen use on vitamin D levels in an Australian population. Results of a randomized controlled trial. Arch Dermatol. 1995 Apr;131(4):415–21. [PubMed]
(49) Sollitto RB, Kraemer KH, DiGiovanna JJ. Normal vitamin D levels can be maintained despite rigorous photoprotection: six years’ experience with xeroderma pigmentosum. J Am Acad Dermatol. 1997 Dec;37(6):942–7. [PubMed]
(50) Gilchrest BA. Sun protection and Vitamin D: three dimensions of obfuscation. J Steroid Biochem Mol Biol. 2007 Mar;103(3-5):655–63. [PubMed]
(51) Canadian Cancer Society . Vitamin D. Canadian Cancer Society; 2008. Available from: http://www.cancer.ca/Canada-wide/Prevention/Use%20SunSense/Vitamin%20D.aspx?sc_lang=en.