In men, but not women, people who walked for both transportation and leisure reported more frequent sunburn. Longer duration walking was not associated with higher sunburn frequency.
Keywords: Sunburn, Physical activity, Walking, Leisure, Transportation
Abstract
Background
The positive association between physical activity and sunburn is a health behavior trade-off between the health benefits of physical activity and increased risk of skin cancer.
Purpose
We assessed walking, which is a common source of physical activity, and the prevalence of sunburn.
Methods
This research used the 2015 National Health Interview Survey of adults (N = 26,632), age ≥ 18 years. We defined four exclusive categories of walking: (a) those who reported not walking; (b) only transportation (to get some place, such as work, a store, or public transit stop); (c) only leisure (such as for fun, relaxation, or exercise); and (d) both categories. We estimated the adjusted prevalence of sunburn by walking category and separately for walking duration; we stratified by gender and sun sensitivity.
Results
The adjusted sunburn prevalence was not different between walking categories for women, but it was for men. Specifically, prevalence was lower for men who reported not walking, 34.1% (95% confidence interval [CI]: 32.2%–36.1%) compared to 38.8% (95% CI: 36.5%–41.2%) who walked for both purposes (p = .003). Walking duration was not associated with sunburn prevalence.
Conclusion
We could not determine whether sunburn occurred during walking trips because the questions were not asked as such. However, the results suggest that walking, unlike leisure-time physical activity (such as exercise, sports, or physically active hobbies), may not generally be associated with sunburn, except for the higher sunburn prevalence for men who walked for both leisure and transportation purposes.
Introduction
Public health communications in the USA, such as Step It Up! The Surgeon General’s Call to Action to Promote Walking and Walkable Communities and The Surgeon General’s Call to Action to Prevent Skin Cancer, address walking and skin cancer as independent issues [1, 2]. Walking is a common source of physical activity accessible to most people [3, 4]. However, those with higher amounts of physical activity also have higher risk of skin cancer, specifically melanoma [5], ostensibly from the higher rates of sunburn among physically active people [6]. Little is known about the association between types of common outdoor physical activities, such as walking, and sunburn [7]. For example, those who play outdoor sports have higher risk of sunburn [8], but it is unknown whether the much more common activity of walking is associated with higher risk of sunburn. Walking for physical activity typically occurs on neighborhood streets, in parks, or on trails, although some occurs in shopping malls or on a treadmill [9].
Better understanding of walking as both a cancer prevention behavior and as a potential cancer risk factor could inform strategies aimed at jointly achieving healthful physical activity and reducing risk of skin cancer. Disaggregation of walking into categories, for leisure or as a means of transportation, is necessary to account for walking-category-specific behaviors and context [10]. This research examined the association between category and duration of walking and sunburn prevalence after accounting for leisure-time physical activity and sun protection behaviors.
Methods
This cross-sectional research used the nationally representative 2015 National Health Interview Survey (NHIS; N = 33,672). The NHIS is an annual household survey of the U.S. noninstitutional adult (age ≥ 18 years) population [11], and a description of demographics is available [6]. The outcome variable was any reported sunburns in the previous 12 months. We defined four exclusive categories of walking reported for the past 7 days: (a) those who reported not walking more than 10 min (no walking); (b) only transportation (walking to get someplace); (c) only leisure (walking for fun, relaxation, or exercise); and (d) both categories [12]. Walking duration for transportation and leisure was calculated from responses to frequency and average duration of trips. Covariates included regular sunscreen use, sun avoidance, and sun protective clothing use. Analyses also adjusted for demographics and covariates related to sunburn risk or walking: leisure-time physical activity level (inactive, insufficiently active, sufficiently active, or highly active) [13], obesity or overweight, needs walking assistance, ever had a skin exam, skin reaction after 2 weeks in the sun (very dark tan, moderate tan, mild tan, burn repeatedly or freckle, or do not go out in the sun), personal or family history of melanoma, ever had cancer, health insurance status, sunless tanning product use, indoor tanning use, smoking status, and binging drinking status [6]. This study was exempt from review by the National Cancer Institute institutional review board because we used publicly available deidentified data.
Statistical Analyses
We examined the associations between walking behavior and any sunburns, controlling for covariates. We assessed variation in sunburn prevalence for walking by category and duration with logistic regression. We stratified by gender and sun sensitivity (any reported skin burn when not protected from the sun for 1 hr) following previous research [6]. We excluded respondents who were unable to walk (n = 894) or had missing responses to any variables (n = 7,040) for an analytic sample of N = 26,632. Among walkers, we categorized the walking duration variables into quartiles, as it was zero-inflated and right skewed. A sensitivity analysis showed that walking duration as a continuous or log-transformed variable produced similar results.
We used SAS-callable SUDAAN, version 11.0 (Research Triangle Institute) to account for the complex sampling design and weights. Significance tests used the adjusted Wald F-test and linear contrasts for differences between walking categories; p < .05 was the level of significance.
Results
Descriptive Statistics
A higher proportion of men reported walking for both purposes (22.1%, 95% confidence interval [CI]: 21.2%–22.2%) compared to women (19.5%, 95% CI: 18.5%–20.5%), whereas a higher proportion of women reported walking for leisure only (35.6%, 95% CI: 34.4%–36.7%) compared to men (28.7%, 95% CI: 27.5%–29.9%) (Table 1).
Table 1.
Weighted unadjusted prevalence (% and 95% confidence intervals [CIs]) for the total population and in exclusive walking categoriesa (rows sum to 100%) for U.S. adults by selected characteristics, National Health Interview Survey, 2015
| Unweighted N | Total population weighted % and 95% CI |
Not walking more than 10 min % and 95% CI |
Transportation only % and 95% CI |
Leisure only % and 95% CI |
Both purposes % and 95% CI |
|
|---|---|---|---|---|---|---|
| Total | 26,632 | 36.0 (35.1–36.9) | 11.1 (10.5–11.6) | 32.2 (31.3–33.1) | 20.8 (20.1–21.5) | |
| Sex | ||||||
| Women | 14,324 | 50.4 (49.6–51.3) | 35.0 (34.0–36.1) | 9.9 (9.2–10.6) | 35.6 (34.4–36.7) | 19.5 (18.5–20.5) |
| Men | 12,308 | 49.6 (48.7–50.4) | 36.9 (35.7–38.2) | 12.3 (11.4–13.1) | 28.7 (27.5–29.9) | 22.1 (21.1–22.2) |
| Age group | ||||||
| 18–24 | 2,508 | 13.2 (12.4–13.9) | 35.1 (32.3–37.8) | 15.6 (13.6–17.6) | 25.6 (23.1–28.1) | 23.8 (21.3–26.2) |
| 25–34 | 4,872 | 18.5 (17.8–19.1) | 33.1 (31.3–34.9) | 11.4 (10.2–12.7) | 32.7 (30.8–34.6) | 22.7 (21.1–24.3) |
| 35–44 | 4,414 | 17.3 (16.6–17.9) | 34.4 (32.3–36.5) | 11.0 (9.9–12.0) | 32.7 (30.6–34.7) | 22.0 (20.2–23.8) |
| 45–64 | 9,083 | 34.7 (33.8–35.5) | 35.3 (33.9–36.5) | 10.6 (9.7–11.5) | 33.8 (32.2–35.4) | 20.2 (18.9–21.5) |
| ≥65 | 5,755 | 16.4 (15.7–17.0) | 43.0 (41.2–44.8) | 8.0 (7.0–9.0) | 32.8 (31.1–34.4) | 16.3 (14.9–17.6) |
| Race/ethnicity | ||||||
| White, non-Hispanic | 16,709 | 65.2 (64.2–66.2) | 35.0 (33.9–36.2) | 9.9 (9.2–10.6) | 34.5 (33.4–35.7) | 20.6 (19.6–21.5) |
| Black, non-Hispanic | 3,235 | 10.9 (10.3–11.6) | 43.0 (40.6–45.3) | 13.7 (11.9–15.5) | 23.1 (21.1–25.1) | 20.3 (18.2–22.4) |
| Hispanic | 4,467 | 16.0 (15.2–16.7) | 38.0 (36.1–39.9) | 13.0 (11.6–14.4) | 28.7 (26.9–30.4) | 20.6 (18.8–21.9) |
| Other raceb | 2,221 | 7.9 (7.5–8.3) | 29.9 (27.2–32.6) | 13.2 (11.4–15.0) | 32.4 (29.7–35.1) | 24.4 (21.9–26.9) |
| At least 1 sunburn in past 12 months | ||||||
| Yes | 8,878 | 36.0 (35.0–37.0) | 30.6 (29.2–31.9) | 11.2 (10.3–12.2) | 34.6 (33.2–36.0) | 23.6 (22.2–24.9) |
| No | 17,754 | 64.0 (63.0–65.0) | 39.0 (37.9–40.1) | 11.0 (10.3–11.6) | 30.8 (29.8–31.8) | 19.2 (18.4–20.1) |
| Skin reaction after 2 weeks in sun | ||||||
| Very dark tan | 3,335 | 12.7 (12.1–13.3) | 36.1 (33.8–38.4) | 12.3 (10.7–13.8) | 30.8 (28.5–33.1) | 20.8 (18.9–22.6) |
| Moderate tan | 8,376 | 31.5 (30.7–32.2) | 34.2 (32.8–35.6) | 10.5 (9.6–11.5) | 34.0 (32.7–35.4) | 21.3 (20.0–22.5) |
| Mild tan | 8,298 | 31.4 (30.6–32.3) | 34.9 (33.5–36.4) | 11.6 (10.6–12.6) | 31.6 (30.2–32.9) | 21.9 (20.7–23.1) |
| Burn repeatedly or freckle |
4,509 | 17.3 (16.7–17.9) | 32.9 (30.9–34.9) | 10.6 (9.3–11.8) | 36.0 (33.8–38.2) | 20.5 (18.7–22.2) |
| Do not go in the sun |
2,114 | 7.2 (6.6–7.7) | 55.6 (52.4–58.8) | 10.2 (8.5–11.8) | 19.7 (17.3–22.1) | 14.6 (12.6–16.7) |
| Regular sun avoidancec | ||||||
| Yes | 11,154 | 40.9 (40.0–41.8) | 39.6 (38.3–40.8) | 11.3 (10.5–12.2) | 30.7 (29.4–31.9) | 18.4 (17.4–19.4) |
| No | 15,478 | 59.1 (58.2–60.0) | 33.5 (32.3–34.6) | 10.9 (10.2–11.6) | 33.2 (32.1–34.3) | 22.4 (21.4–23.5) |
| Regular sun protective clothing used | ||||||
| Yes | 10,443 | 36.2 (35.4–37.1) | 34.5 (33.2–35.7) | 11.3 (10.4–12.2) | 31.7 (30.4–32.9) | 22.6 (21.4–23.8) |
| No | 16,189 | 63.8 (62.9–64.6) | 36.8 (35.7–38.0) | 10.9 (10.2–11.6) | 32.5 (31.3–33.6) | 19.8 (18.9–20.7) |
| Regular sunscreen use (SPF15+)e | ||||||
| Yes | 8,322 | 32.7 (31.8–33.5) | 26.2 (24.9–27.6) | 10.0 (9.1–10.9) | 38.6 (37.0–40.2) | 25.2 (23.7–26.6) |
| No | 18,310 | 67.3 (66.5–68.2) | 40.7 (39.6–41.8) | 11.6 (10.9–12.3) | 29.0 (28.0–30.0) | 18.7 (17.9–19.4) |
| Physical activity levelf | ||||||
| Inactive | 7,932 | 28.1 (27.2–29.0) | 63.5 (62.0–65.1) | 12.5 (11.4–13.5) | 15.2 (14.1–16.2) | 8.9 (8.0–9.7) |
| Insufficiently active |
5,387 | 20.5 (19.8–21.2) | 33.7 (32.0–35.5) | 11.2 (10.0–12.4) | 37.4 (35.6–39.2) | 17.7 (16.3–19.1) |
| Sufficiently active |
4,355 | 16.8 (16.1–17.5) | 22.4 (20.7–24.2) | 11.8 (10.5–13.2) | 41.8 (39.8–43.9) | 23.9 (22.0–25.7) |
| Highly active | 8,958 | 34.6 (33.7–35.6) | 21.5 (20.2–22.7) | 9.5 (8.7–10.3) | 38.2 (36.7–39.7) | 30.8 (29.3–32.3) |
aReported walking categories for at least 10 min in the past 7 days.
bAmerican Indian, Alaskan Native, Asian, other, or multiple race
cSun avoidance was defined as always or usually staying in the shade or responding not going into the sun for any sun protective question.
dSun protective clothing was defined as always or usually wearing at least one: wide-brimmed hat, long sleeved shirt, or long clothing to the ankles.
eRegular sunscreen use was defined as always or usually using sunscreen with SPF15+ (sun protection factor)
fIndividuals were categorized into four activity levels based on the 2008 Physical Activity Guidelines for Americans: highly active (>300 min/week of light or moderate-intensity aerobic activity, 150 min of vigorous-intensity aerobic activity, or an equivalent combination per week [i.e., moderate-intensity equivalent activity]), sufficiently active (150–300 min/week of moderate-intensity equivalent activity), insufficiently active (some activity but less than 150 min/week of moderate-intensity equivalent activity), and inactive (no light to moderate or vigorous-intensity aerobic activity for at least 10 min).
Sunburn and Walking Categories
Sunburn prevalence, adjusted for covariates, was not significantly associated with walking categories for women (F[3, 14,320] = 1.15, p = .32), but it was for men (F[3, 12,304] = 3.25, p = .02). Specifically, sunburn prevalence was lower for men who reported no walking (34.1%; 95% CI: 32.2%–36.1%) compared to men who walked for both purposes (38.8%; 95% CI: 36.5%–41.2%; F[1, 12,306] = 9.24, p = .003; Table 2). Similarly, sunburn was three percentage points higher in men who reported any walking compared to no walking (F[1, 12,306] = 7.26, p = .008) and there was not a significant difference for women (F[1, 14,320] = 0.45, p = .50).
Table 2.
Weighted and adjusteda prevalence (% and 95% confidence intervals [CIs]) of ≥1 sunburns in past 12 months for U.S. adults for walking categoriesb and selected covariates, National Health Interview Survey, 2015
| Women | Men | |||
|---|---|---|---|---|
| Adjusted, ≥1 sunburns % (95% CI) |
p | Adjusted, ≥1 sunburns % (95% CI) |
p | |
| Walking | .32 | .02 | ||
| Not walking more than 10 min | 35.2 (33.1–37.2) | 34.1 (32.2–36.1)c | ||
| Transportation only | 37.7 (34.5–41.0) | 37.3 (34.3–40.4) | ||
| Leisure only | 35.0 (33.1–36.9) | 36.0 (33.9–38.2) | ||
| Both purposes | 36.8 (34.5–39.1) | 38.8 (36.5–41.2)c | ||
| Age group | <.0001 | <.0001 | ||
| 18–24 | 52.1 (47.7–56.4) | 49.9 (45.8–54.0) | ||
| 25–34 | 47.6 (44.9–50.3) | 46.9 (44.3–49.6) | ||
| 35–44 | 43.6 (41.0–46.2) | 43.1 (40.2–46.1) | ||
| 45–64 | 30.6 (28.8–32.5) | 32.2 (30.4–34.0) | ||
| ≥65 | 13.1 (11.0–15.5) | 14.2 (12.4–16.4) | ||
| Race/ethnicity | <.0001 | <.0001 | ||
| White, non-Hispanic | 41.4 (39.7–43.1) | 42.3 (40.5–44.2) | ||
| Black, non-Hispanic | 14.7 (12.6–17.0) | 9.0 (7.1–11.3) | ||
| Hispanic | 30.5 (27.7–33.4) | 29.5 (26.3–32.9) | ||
| Other, non-Hispanic | 25.5 (21.9–29.4) | 26.1 (22.3–30.4) | ||
| Physical activity leveld | .02 | .0001 | ||
| Inactive | 33.0 (30.7–35.3) | 31.1 (28.6–33.7) | ||
| Insufficiently active | 36.3 (34.2–38.6) | 37.8 (35.3–40.3) | ||
| Sufficiently active | 38.0 (35.7–40.4) | 37.2 (34.8–39.7) | ||
| Highly active | 36.0 (34.1–37.9) | 37.9 (35.9–40.0) | ||
| Skin reaction after 2 weeks in sun | <.0001 | <.0001 | ||
| Very dark tan | 30.9 (27.8–34.1) | 33.9 (30.9–37.1) | ||
| Moderate tan | 35.7 (33.6–37.8) | 36.1 (34.2–38.2) | ||
| Mild tan | 35.0 (33.1–37.0) | 34.8 (32.8–36.9) | ||
| Burn repeatedly or freckle |
42.5 (40.3–44.8) | 44.8 (41.9–47.8) | ||
| Do not go out in the sun | 20.9 (17.1–25.4) | 20.5 (15.8–26.3) | ||
| Regular sun avoidancee | .0003 | .001 | ||
| Yes | 33.4 (31.7–35.1) | 33.4 (31.2–35.7) | ||
| No | 37.5 (35.9–39.1) | 37.3 (35.8–38.8) | ||
| Regular sun protective clothing usef | .17 | .47 | ||
| Yes | 34.6 (32.6–36.6) | 36.6 (34.7–38.5) | ||
| No | 36.1 (34.8–37.5) | 35.8 (34.2–37.5) | ||
| Regular sunscreen use (SPF15+)g | .0001 | <.0001 | ||
| Yes | 37.9 (36.3–39.6) | 41.2 (38.8–43.7) | ||
| No | 33.7 (32.1–35.3) | 34.4 (32.9–35.9) | ||
aCovariates in addition to those listed: education status, marital status, foreign-born status, needs walking assistance, U.S. Census region, obesity or overweight, smoking status, binge drinking, tanning bed use, ever had a skin exam, ever had cancer, family history of melanoma, personal history of melanoma, sunless tanning product use, and health insurance status.
bReported walking categories for at least 10 min in the past 7 days.
cSignificant linear contrast of regression coefficients: F(1, 12,306) = 9.24, p = .003.
dIndividuals were categorized into four activity levels based on the 2008 Physical Activity Guidelines for Americans: highly active (>300 min/week of light or moderate-intensity aerobic activity, 150 min of vigorous-intensity aerobic activity, or an equivalent combination per week [i.e., moderate-intensity equivalent activity]), sufficiently active (150–300 min/week of moderate-intensity equivalent activity), insufficiently active (some activity but less than 150 min/week of moderate-intensity equivalent activity), and inactive (no light to moderate or vigorous-intensity aerobic activity for at least 10 min).
eSun avoidance was defined as always or usually staying in the shade or responding not going into the sun for any sun protective question.
fSun protective clothing was defined as always or usually wearing at least one: wide-brimmed hat, long sleeved shirt, or long clothing to the ankles.
gRegular sunscreen use was defined as always or usually using sunscreen with SPF15+ (sun protection factor).
No significant associations between sunburn and walking were found among sun-sensitive individuals (N = 13,974) (Fig. 1).
Fig. 1.
Weighteda and adjustedb prevalence (% and 95% confidence intervals) ≥1 sunburns in past 12 months by walking categoryc for sun-sensitive individualsd, National Health Interview Survey, 2015. aError bars represent upper and lower bounds of 95% confidence interval. bCovariates: age group, race/ethnicity, education, marital status, foreign-born status, needs walking assistance, U.S. Census region, obesity or overweight, physical activity level, smoking status, binge drinking, sun avoidance, sunscreen use, sun protective clothing use, skin reaction after 2 weeks in sun, tanning bed use, ever had a skin exam, ever had cancer, family history of melanoma, personal history of melanoma, sunless tanning product use, and health insurance status. cReported walking categories for at least 10 min in the past 7 days. dSun-sensitive individuals defined as those reporting any skin burn when not protected from the sun for 1 hr.
Walking Duration and Sunburn
Minutes of walking, in models adjusted for covariates, were not significantly associated with sunburn for women (transportation, F[4, 14,319] = 1.34, p = .26; leisure, F[4, 14,319] = 1.76, p = .14) or men (transportation, F[4, 12,303] = 2.26, p = .06; leisure, F[4, 12,303] = 1.60, p = .17). Similarly, among sun-sensitive individuals, the adjusted association between walking minutes and sunburn was not significant for women (transportation, F[4, 7,805] = 0.67, p = .61; leisure, F[4, 7,805] = 1.39, p = .24) or men (transportation, F[4, 6,159] = 0.82, p = .51; leisure, F[4, 6,159] = 1.38, p = .24).
Discussion
With one exception, the results suggest that neither walking category nor duration was generally associated with sunburn prevalence. The one caveat concerned men, where the difference in sunburn was nearly 5 percentage points higher between those who walked for both leisure and transportation purposes compared to men who reported not walking at least 10 min.
These results differ from prior population studies where general physical activity has been strongly associated with increased sunburn [6, 14]. Some reasons walking is different from general physical activity may be due to type of clothing (e.g., clothing worn while walking to work may cover more skin than clothing worn while jogging), time of day, or context. Also, in contrast to findings of a gender difference in general physical activity, women reported more leisure walking trips than men, but they did not report more sunburn, which is a consistent gender-related finding in prior sunburn research [6]. We found differences in sun protection between genders: more women used sunscreen and avoided the sun; however, more men wore protective clothing, similar to prior research [6].
Limitations
Our purpose was to examine the association between walking and sunburn while controlling for overall physical activity. However, our measure of physical activity may be a limitation with these data. First, it was limited to leisure-time physical activity. Second, we compared models controlling for leisure-time physical activity versus not controlling; findings in models controlled for physical activity were attenuated. This attenuation may be due to controlling for the effect of physical activity; however, it may also be due to measurement issues. There was a potential overlap between reported walking and leisure-time activity, so inclusion of this variable could be overcontrolling for the association of interest. For example, some respondents could have reported walking activity during the walking questions and reported leisure and transportation walking as part of their leisure-time activity. It is likely that the true association may lie somewhere between the two models’ estimates, and our main findings adjusting for physical activity may be conservative.
The survey questions referenced different time periods. Walking questions referred to the past 7 days, sunburn questions referred to the previous 12 months, and sun protective questions referred to an unspecified time: on a warm sunny day. The different temporal spans of these questions and the seasonality and daily fluctuations of UV risk may limit interpretability of these findings. Indoor walking is a common type of leisure-time walking among some sociodemographic groups (e.g., less than high school education; <30 or >64 years of age) [9]. This may confound some of the association between physical activity and sunburn in these groups. Lastly, the degree to which sunburn (and sun protection) occurred while walking and time of day of walking trips were unknown and limit the validity of these findings.
Conclusion
Walking, one of the most commonly reported forms of physical activity, does not appear to have a similar association with sunburn as general physical activity. Still, sunburn may occur with outdoor walking. Public health messages that encourage walking should advise sun protection, with special attention to men, to reduce sunburn and skin cancer risk.
Acknowledgements
Funding: No funding received.
Compliance with Ethical Standards
Authors’ Statement of Conflict of Interest and Adherence to Ethical Standards Authors Tribby, Berrigan, and Perna declare that they have no conflict of interest.
Authors’ Contributions: C.P.T., D.B., and F.M.P., conceptualized the study, developed the methodology, and edited the manuscript. C.P.T. conducted the formal analysis and original draft preparation. All authors read and approved the final version.
Ethical Approval: This study was exempt from NCI IRB, as it was an analysis of secondary data collected by the National Center for Health Statistics (NCHS) that was de-identified and made publicly available.
Informed Consent: The National Center for Health Statistics (NCHS), which is part of the Centers for Disease Control and Prevention (CDC), conducts the National Health Interview Survey in accordance with The National Health Survey Act of 1956 and all prevailing federal government regulations and policies concerning informed consent and human subjects research.
References
- 1. US Department of Health and Human Services. The Surgeon General’s Call to Action to Prevent Skin Cancer. Washington, DC: Office of the Surgeon General (US); 2014. [Google Scholar]
- 2. US Department of Health and Human Services. Step It Up! The Surgeon General’s Call to Action to Promote Walking and Walkable Communities. Washington, DC: Office of the Surgeon General (US); 2015. [PubMed] [Google Scholar]
- 3. Berrigan D, Carroll DD, Fulton JE, et al. . Vital signs: walking among adults - United States, 2005 and 2010. Morb Mortal Wkly Rep. 2012;61:595–601. [PubMed] [Google Scholar]
- 4. Ussery EN, Carlson SA, Whitfield GP, Watson KB, Berrigan D, Fulton JE. Walking for transportation or leisure among U.S. Women and Men - National Health Interview Survey, 2005-2015. MMWR Morb Mortal Wkly Rep. 2017;66:657–662. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5. Moore SC, Lee IM, Weiderpass E, et al. . Association of leisure-time physical activity with risk of 26 types of cancer in 1.44 million adults. JAMA Intern Med. 2016;176:816–825. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6. Holman DM, Ding H, Guy GP Jr, Watson M, Hartman AM, Perna FM. Prevalence of Sun protection use and sunburn and association of demographic and behaviorial characteristics with sunburn among US adults. JAMA Dermatol. 2018;154:561–568. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7. Geller AC, Jablonski NG, Pagoto SL, et al. . Interdisciplinary perspectives on sun safety. JAMA Dermatol. 2018;154:88–92. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8. Wysong A, Gladstone H, Kim D, Lingala B, Copeland J, Tang JY. Sunscreen use in NCAA collegiate athletes: identifying targets for intervention and barriers to use. Prev Med. 2012;55:493–496. [DOI] [PubMed] [Google Scholar]
- 9. Eyler AA, Brownson RC, Bacak SJ, Housemann RA. The epidemiology of walking for physical activity in the United States. Med Sci Sports Exerc. 2003;35:1529–1536. [DOI] [PubMed] [Google Scholar]
- 10. Lee C, Moudon AV. Correlates of walking for transportation or recreation purposes. J Phys Act Health. 2006;3:S77–S98. [DOI] [PubMed] [Google Scholar]
- 11. National Center for Health Statistics. Survey Description, National Health Interview Survey, 2015. Hyattsville, MD: National Center for Health Statistics; 2016. [Google Scholar]
- 12. Paul P, Carlson SA, Carroll DD, Berrigan D, Fulton JE. Walking for transportation and leisure among U.S. Adults–National Health Interview Survey 2010. J Phys Act Health. 2015;12(suppl 1):S62–S69. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13. Physical Activity Guidelines Advisory Committee. Physical Activity Guidelines Advisory Committee Report, 2008. Washington, DC: US Department of Health and Human Services; 2008:A1–H14. [DOI] [PubMed] [Google Scholar]
- 14. Jardine A, Bright M, Knight L, Perina H, Vardon P, Harper C. Does physical activity increase the risk of unsafe sun exposure? Health Promot J Austr. 2012;23:52–57. [DOI] [PubMed] [Google Scholar]