An Inexpensive High-Temporal Resolution Electronic Sun Journal for Monitoring Personal Day to Day Sun Exposure Patterns

Abstract

Exposure to natural sunlight, specifically solar ultraviolet (UV) radiation contributes to lifetime risks of skin cancer, eye disease, and diseases associated with vitamin D insufficiency. Improved knowledge of personal sun exposure patterns can inform public health policy; and help target high-risk population groups. Subsequently, an extensive number of studies have been conducted to measure personal solar UV exposure in a variety of settings. Many of these studies, however, use digital or paper-based journals (self-reported volunteer recall), or employ cost prohibitive electronic UV dosimeters (that limit the size of sample populations), to estimate periods of exposure. A cost effective personal electronic sun journal (ESJ) built from readily available infrared photodiodes is presented in this research. The ESJ can be used to complement traditional UV dosimeters that measure total biologically effective exposure by providing a time-stamped sun exposure record. The ESJ can be easily attached to clothing and data logged to personal devices (including fitness monitors or smartphones). The ESJ improves upon self-reported exposure recording and is a cost effective high-temporal resolution option for monitoring personal sun exposure behavior in large population studies.

Keywords: erythema; infrared; skin cancer; sun journal; ultraviolet; vitamin D.

Figure 1

Circuit design and operation under limited (A) and saturated (B) exposure states. Maximum output current occurs when the diode saturates and is limited to less than 0.1 mA to prolong battery life [(A) cathode, (B) anode].

Figure 2

Sky view assembly [(A) side and (B) top view] used to test the infrared photodiode sensitivity to increasing levels of diffuse solar radiation (red—shaded sky hemisphere, black—shade shield, dotted circle—visible sky view of nominal radius 1).

Figure 3

Photodiode voltage plotted as a function of sky view.

Figure 4

Photodiode voltage versus distance from an incandescent light globe.

Figure 5

Electronic sun journal output monitored in different static outdoor environments (upper line—shade structure, middle blue—dense tree shade, bottom red—light tree shade).

Figure 6

Personal outdoor exposure pattern determined from the voltage output of the electronic sun journal for an individual moving about an outdoor environment (A) 22 September; (B) 24 September midmorning, (C) 24 September afternoon, (D) 26 September; (E) 27 September; (F) 18 January midmorning; (G) 18 January afternoon; (H) 1 February; and (I) 29 March.