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Ultraviolet radiation protection by a beach umbrella
María P Utrillas1, José A Martínez-Lozano, Manuel Nuñez
1Solar Radiation Group, Departamento de Física de la Tierra, Universidad de Valencia, Valencia, Spain.
Photochemistry and Photobiology
|January 12, 2010
Summary
Beach umbrellas block direct UV rays but allow some diffuse UV radiation. A sky view factor model shows about 34% of UV irradiance reaches the ground near an 80cm umbrella, impacting human UV exposure.
Area of Science:
- Atmospheric Science
- Photobiology
- Environmental Health
Background:
- Ultraviolet (UV) radiation poses health risks.
- Beach umbrellas offer shade but their UV shielding effectiveness is not fully quantified.
Purpose of the Study:
- To model the UV irradiance not intercepted by a beach umbrella.
- To assess UV exposure for humans under beach umbrellas.
Main Methods:
- Utilized a sky view factor model to calculate the fraction of diffuse UV irradiance reaching the ground.
- Assumed isotropic diffuse irradiance, an 80 cm radius umbrella, and a 100 cm height.
- Validated model with field measurements of UV irradiance.
Main Results:
- Approximately 34% of incident horizontal UV irradiance was not intercepted by the umbrella.
- Model predictions aligned with experimental measurements.
- Extended model to simulate UV receipt by standing or sitting human figures.
Conclusions:
- Beach umbrellas provide partial protection against diffuse UV radiation.
- A significant portion of UV irradiance can still reach individuals under umbrellas.
- Further research can refine UV exposure assessments for beachgoers.
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