Use of Shade in U.S. and Australian City Parks

This study is designed to understand the value of shade development in skin cancer prevention and test predictions from social ecologic models that health behavior results from the interplay among the built environment, social environment, and setting features. Use of shade is recommended by health authorities worldwide. However, shade provision requires expensive physical environment changes and may be effective only when health education has created a social environment (e.g., norms) that motivates its use. A multi-national research team will explore the use of built shade in passive recreation areas (i.e., areas for sitting/ standing while socializing, preparing/eating a meal, watching/coaching sports, watching a concert, taking a class, or waiting, or areas where people stroll for sightseeing, while observing outdoor displays, or shopping) within public parks and compare use between the United States (i.e., Denver, Colorado) and Australia (i.e., Melbourne, Victoria) to prospectively test the moderating influence of social environment on the built environment. Pilot studies confirmed that adults in Melbourne had stronger sun protection habits and norms than adults in Denver. The specific aims of the project are to: a) introduce built shade structures (i.e., shade sails) in public parks in Denver and Melbourne; b) compare the use of passive recreation areas with and without built shade; c) compare the change in use of the passive recreation areas in Denver and Melbourne after introduction of built shade, and d) examine the relationship among social environment and physical features of the environment and built shade.The research team will build shade sails at passive recreation areas in public parks and compare use of the passive recreation areas to unshaded passive recreation areas in a randomized pretest-posttest controlled design. Passive recreation areas will be enrolled in one of three annual sample waves and stratified by location (72 in Denver and 72 in Melbourne). In each wave, passive recreation areas will be pretested in a first summer, further stratified based on baseline use, and randomized following pretest to construction of a shade sail or an untreated control group in a 1:3 ratio. Posttesting will occur the following summer, after construction of the shade sails. In total, 36 passive recreation areas will be randomized to the intervention group with shade sail construction (18 per city) and 108 passive recreation areas to the untreated control group with no shade sails (54 per city). The primary outcome measure will be use of the passive recreation areas, observed by trained research assistants. The secondary outcome measure will be the potential ultraviolet radiation exposure, assessed by hand-held meters during the observations of the passive recreation areas. Data collection will occur during 30-minute periods between 11 am and 3 pm on on 4 weekend days over 20-weeks in the summer. Primary analyses will be performed on the probability the passive recreation areas are in use when observed and secondary analysis, on estimated standard erythemal dose of ultraviolet radiation during 30 minutes, using intent-to-treat methods.