The anatomical distribution of sunlight

Area of Science:

• Environmental science
• Dermatology
• Radiation physics

Background:

• Understanding ultraviolet (UV) radiation exposure is crucial for assessing health risks, such as skin cancer.
• Previous studies have focused on broad UV exposure, but detailed distribution on the human body is less understood.
• UV radiation varies significantly based on body orientation and environmental factors.

Purpose of the Study:

• To quantify the relative distribution of natural UV radiation across different body sites.
• To determine if weather conditions influence UV dose distribution on the body.
• To provide data for more accurate personal UV dosimetry.

Main Methods:

• Polysulphone film dosimeters were placed on ten sites of an unclothed manikin.
• Measurements were taken over 2 hours around solar noon on 19 days during late summer in Canterbury, U.K.
• Relative UV doses were calculated for each body site.

Main Results:

• Vertical body surfaces received approximately 50% of the UV dose compared to the vertex (top of the head).
• The relative UV doses at different body sites were consistent across various weather conditions.
• The vertex consistently received the highest relative UV dose.

Conclusions:

• The distribution of UV radiation on the body is predictable and primarily influenced by surface orientation.
• Weather conditions do not significantly alter the relative UV dose distribution across body sites.
• These findings can inform protective strategies and improve UV exposure assessments.