摘要：Objectives. To test whether shade sails will increase the use of passive recreation areas (PRAs). Methods. We conducted a stratified randomized pretest–posttest controlled design study in Melbourne, Australia, and Denver, Colorado, in 2010 to 2014. We randomized a sample of 144 public parks with 2 PRAs in full sun in a 1:3 ratio to treatment or control. Shade sails were built at 1 PRA per treatment park. The outcome was any use of the study PRA (n = 576 pretest and n = 576 posttest observations; 100% follow-up). Results. Compared with control PRAs (adjusted probability of use: pretest = 0.14, posttest = 0.17), use of treatment PRAs (pretest = 0.10, posttest = 0.32) was higher at posttest (odds ratio [OR] = 3.91; 95% confidence interval [CI] = 1.71, 8.94). Shade increased use of PRAs in Denver (control: pretest = 0.18, posttest = 0.19; treatment: pretest = 0.16, posttest = 0.47) more than Melbourne (control: pretest = 0.11, posttest = 0.14; shaded: pretest = 0.06, posttest = 0.19; OR = 2.98; 95% CI = 1.09, 8.14). Conclusions. Public investment in shade is warranted for skin cancer prevention and may be especially useful in the United States. Trial Registration. Clinicaltrials.gov identifier {"type":"clinical-trial","attrs":{"text":"NCT02971709","term_id":"NCT02971709"}} NCT02971709 . Skin cancer is among the most common cancers in light-skinned populations worldwide, and melanoma incidence has increased beyond that expected because of population growth and aging. 1 There will be an estimated 87 110 cases of melanoma in the United States 2 and 13 941 cases of melanoma in Australia 3 in 2017. The primary risk factor for skin cancer, and the most avoidable, is exposure to solar ultraviolet (UV) radiation. 4 To prevent skin cancer, individuals are advised to minimize UV exposure by staying in the shade. 2,5 Permanent purpose-built shade can provide known amounts of reduction of UV exposure. 6 Shade is part of the built environment, 7 which according to social-ecological models 8 can have direct effects on behaviors (e.g., increasing individuals shaded, providing a visible cue for sun protection, and enabling access to protection without planning 9,10 ). Shade may attract high-risk individuals with unfavorable attitudes toward sun safety to use shade for maintaining comfortable body temperatures. 11 Identifying environmental features amenable to change holds promise for improving population health 7 ; however, evidence is limited mainly to cross-sectional or quasi-experimental designs with scant prospective trials. 12 The prevalence of, trends in, 13,14 and demographic and attitudinal correlates of shade use, along with the association of shade with temperature and sunburn incidence, have been reported. 15–17 A study in Melbourne, Australia, secondary schools remains the only prospective randomized trial of purpose-built shade for sun protection 9,11 ; it found that students used rather than avoided shade. 11 The ability to improve sun protection by introducing shade needs to be tested in other locations and with adults. Public parks are popular for outdoor recreation, and shade is a desirable feature in parks. 10 The present trial prospectively tested the effect of purpose-built shade on use of passive recreation areas (PRAs) in public parks (i.e., areas used for sitting or standing while socializing, preparing or eating a meal, watching or coaching sports, watching a concert, taking a class, or waiting, or areas where people stroll for sightseeing or while observing outdoor displays). We hypothesized that the introduction of shade sails over PRAs would increase the use of the PRAs by park visitors compared with unshaded control PRAs (hypothesis 1). Social-ecological models suggest that built environmental features influence health risks through their interplay with the social environment. Australia has a longer history of comprehensive efforts to prevent skin cancer than the United States. 18,19 Accordingly, stronger norms for sun safety in Australia than in the United States are expected, so we hypothesized that the increase in use of PRAs at shaded PRAs would be larger in Melbourne, Australia than in Denver, Colorado (hypothesis 2).
