A Randomized Study of Shade Sails and Passive Recreation in Public Parks in Two Hemispheres

A Randomized Study of Shade Sails and Passive Recreation in Public Parks in Two Hemispheres

Skin cancer is the most common type of cancer1 but the primary risk factor for skin cancer, UV exposure, is the most avoidable.2 Purpose-built shade not only reduces UV exposure,3 it can also come with other benefits like provide protection without requiring planning4 and may even provide protection for individuals with negative attitudes towards sun safety who seek shade to keep cool.5

In a recent publication in American Journal of Public Health, KB’s Dr. David Buller, Mary Buller and collaborators in Australia, at the University of Melbourne (Dr. Dallas English) and Cancer Council Victoria, (Dr. Suzanne Dobbinson) conducted a stratified randomized study in Melbourne, Australia and Denver, Colorado where shade sails were built in 1 of 2 passive recreation areas (PRAs) in full sun in 144 parks (71 in Melbourne and 73 in Denver). The use of the PRAs with shade sails built as part of the study were compared with the nearby non-shaded PRAs for use by park visitors. The authors tested two hypotheses – the first being that the introduction of shade sails over PRAs would increase the use of these PRAs by visitors compared to unshaded PRAs – and the second being that the increase in use of shaded PRAs would be larger in Melbourne, Australia than Denver, Colorado due to stronger norms for sun safety in Australia than the United States.

Public parks enrolled in the study had to contain at least two unshaded PRAs that were in full sun at pretest, and one of the two PRAs had to contain a space where a shade sail could be constructed. Trained observers made observations at the PRAs for 30-minute periods on four weekend days during a 20-week period in the summer months for each city at pretest and posttest to determine the number of visitors during peak UV hours (11 am to 3 pm). Shade sails were designed to be attractive while also providing shade during peak UV times and the shade cloth selected reduced UV by at least 94%.

Observations of PRA use by adults were recorded along with a variety of characteristics about the visitors using a customized mobile app on an Android tablet. Observers also recorded any use of the comparison PRA and weather conditions. Temperature data from city meteorological stations were later obtained for the hour closest to the observation time. A total of 576 pretest and 576 posttest observations were performed at the 144 parks.

Results showed that hypothesis 1 was supported as shaded PRAs were more likely to be used at posttest than unshaded control PRAs. Hypothesis 2, however, was not corroborated as the installation of shade sails increased the probability of PRA use in Denver more than in Melbourne.

Authors suggest the reason for less use in Melbourne could be due to Australians, who have stronger sun safety norms than Coloradoans, spending less time outdoors during midday to reduce UV exposure. Additionally, authors noted that parks in Denver were in urban areas where residents may rely on parks to compensate for lack of yard pace whereas the parks in Melbourne were in suburban areas where residential yard space is more common and residents may be less motivated to use parks. Lastly, authors mention that due to more prominent sun safety efforts in Melbourne compared to Denver, Australians may not consider another shade sail to be noteworthy whereas Coloradoans may notice the shade sails more as they are less common.

This research was supported by a grant from the National Cancer Institute (RO1CA140367; Dr. David Buller, PI). Collaborators included Mary Buller from KB and Dr. Dallas English, Jody Simmons, Dr. James Chamberlain, Dr. Melanie Wakefield, and Dr. Suzanne Dobbinson from Cancer Council Victoria in Melbourne, Australia.


  1. Skin cancer. American Cancer Society Web site. Available at: http://www.cancer.org/cancer/skincancer/index. Published 2013.
  2. Gallagher RP, McLean DI, Yang CP, et al. Suntan, sunburn, and pigmentation factors and the frequency of acquired melanocytic nevi in children. Similarities to melanoma: the Vancouver Mole Study. Archives of Dermatology. 1990;126(6):770-776. PM:2346321.
  3. Gies P, Mackay C. Measurements of the solar UVR protection provided by shade structures in New Zealand primary schools. Photochemistry and Photobiology. 2004;80(2):334-339. PM:15264956.
  4. Parisi A, Turnbull DJ. Shade provision for UV minimization: a review. Photochemical & Photobiological Sciences. 2014;90(3):479-490.
  5. Dobbinson S, Jamsen K, McLeod K, et al. Maximising students’ use of purpose-built shade in secondary schools: quantitative and qualitative results of a built-environment intervention. Health & Place. 2014;26:136-142.


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