Article publication date:
August 2022
Authored by:
Dobbinson et al.
Summary:
This study assessed ultraviolet (UV) radiation exposure in public parks in Melbourne and Denver to assess the UV protection provided by built-shades located in the parks. The UV measurements were conducted as part of a randomized control trial of built-shade using a pretest-posttest controlled design. The study measured the UV levels of 144 park areas in three annual waves in each city as a pre-test; while during post-test, 108 of them remained as control and 36 had shade structures built. A total of 1,144 UV measurements were conducted in all park areas. UV exposure, in terms of Standard Erythemal Dose (SEDs), during 30-minute potential use of park areas was estimated. Further, observation of environmental conditions (e.g., clear skies, cloud present, solar elevation) was also conducted. The results showed that UV exposure levels in the parks, both during cloudy and clear sky days, tend to increase with solar elevation angle. Further, the built shades at PRAs provided a significant reduction of UV exposures. On average, the UV levels at the shaded areas of the parks were about 3 SEDs lower than the unshaded areas (5 SEDs), during times of high solar elevation (~75◦) on cloudless days.
Link to:
Published In:
The International Journal of Environmental Research and Public Health
Commentary by ARPANSA:
The study provides some key data on the extent of UV reduction after shades structures are built in public park areas. The main conclusion of the study that building shades provides considerable protection against UV exposure (by more than 50%) is consistent to previous similar investigations (e.g., Vanos et al., 2017). However, the estimated UV dose under built shades is still high and additional sun protection measures should be used (e.g., use of sunscreen, hats, clothing, sunglasses), especially on clear sky summer days to avoid sunburn during longer outdoor activities. The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) provides evidence-based public health messages in relation to UV protection measures, and provides a real time UV index and estimation of UV dose. ARPANSA recommends 1 SED per day as a safe UV exposure level for most people; and a typical spring day (e.g., 9th November) in Melbourne measured a total UV dose of 42 SEDs. Therefore, all sun protection measures are important, and hence, need to be used even when built shades are available while conducting outdoor activities.
