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Ambient ultraviolet radiation levels in public shade settings
1School of Mathematics, Computer Sciences and Physics, James Cook University, Townsville, Queensland, Australia. Aurel.Moise@jcu.edu.au
International Journal of Biometeorology
|January 20, 2000
Summary
Shade quality varies significantly, with dense foliage offering the best protection against harmful solar ultraviolet-B (UVB) radiation. Even shaded areas require adequate overhang to prevent scattered UVR exposure.
Area of Science:
- Environmental Science
- Public Health
- Dermatology
Background:
- Increased awareness of solar ultraviolet radiation (UVR) harms drives demand for shade, especially in tropical regions.
- Solar UVR exposure, particularly ultraviolet-B (UVB), poses significant health risks.
Purpose of the Study:
- To quantify the effectiveness of various shade settings in Townsville, Australia, against solar UVR.
- To assess the ratio of unshaded to shaded UVR exposure (UVB-SPR) for different shade types.
Main Methods:
- Broad-band radiation sensors measured ultraviolet-A, ultraviolet-B, and daylight in shaded and unshaded horizontal and vertical directions.
- Measurements were taken at eight shade locations in Townsville from December 1997 to May 1998.
- The UVB/shade protection ratio (UVB-SPR) was calculated to evaluate shade quality.
Main Results:
- UVB-SPR varied greatly among shade settings; beach umbrellas offered minimal protection, while dense foliage provided the most.
- House verandah roofs offered limited protection if exposed to afternoon sun.
- Cloud cover reduced UVB-SPR due to increased diffuse radiation.
- Only one shade setting met the suggested UVB-SPR of 15 or higher.
Conclusions:
- Shade from direct sunlight alone is insufficient for adequate solar UVR protection.
- The construction and overhang of shade structures are critical for determining UVR exposure levels.
- Adequate shade structures with sufficient overhang are recommended to minimize scattered UVR exposure.