Sunlight Illustration
About DSunLife

About DSunLife

DSunlife is designed to assist users in managing their sun exposure to optimize vitamin D production while minimizing the risks associated with excessive sun exposure, such as sunburn, skin damage and skin cancer.

Its main benefit is showing that only a relatively short period of sun exposure is required to obtain and maintain sufficient vitamin D levels.

How To Use The App

How To Use The App

  1. Select Skin Shade: Pick a skin shade closest to yours.
  2. Enter Age & Skin Exposure: Input your age and estimate the amount of skin exposed (front and back).
  3. Use Timer for Sunbathing: Start the timer, sunbathe on one side, then restart the timer and flip to the other side.
  4. The App Calculates Safe Sun Time: The app considers your location, time, date, skin type, and age to determine safe sun exposure times.
  5. Sunbathing Guidance: The app advises if it's too late in the day or too close to winter for effective sunbathing and Vitamin D production.
The Science

The Science

The app calculates UVB normal and diffuse irradiance using a model developed by Bird [1]. This model aligns well with the more advanced libRadTran model[2]. The app's focus is on UVB irradiance as only UVB produces vitamin D within the skin. There is also a strong association between chronic sunburns from UVB exposure and the subsequent risk of skin cancer [3]. To estimate safe sun exposure times, the app employs the minimal erythema dose (MED) concept. MED is the amount of sun exposure that causes minimal skin reddening several hours later.

While adequate vitamin D levels have several benefits [4,6], supplementation is recommended to reduce skin cancer risk [7]. However, there may be added benefits of sun exposure [8]. The app uses MED to determine the maximum sun exposure that minimizes the likelihood of nonmelanoma skin cancer. Different MED doses for various skin types are based on research by Dornelles et al [3]. Additionally, to calculate vitamin D production in the skin, the app utilizes the relationship identified by Robert P. Heaney, as discussed by Armas et al [5].

References
[1] R.E. Bird, Solar Energy, 32, 461-471, 1984.
[2] libRadTran, www.libradtran.org.
[3] S. Dornelles et al, Photochemistry and Photobiology, 79, 540-544, 2004.
[4] M.F. Holick, N Engl J Med, 357, 266-281, 2007.
[5] L.A.G. Armas et al, J Am Acad Dermatol, 57, 588-593, 2007.
[6] J. Wacker and M.F. Holick, Dermato-Endocrinology 5, 51-108, 2013.
[7] J. D'Orazio et al, Int J Mol Sci, 14 12222-12248, 2013.
[8] D. Liu et al, J Invest Dermatol, 134, 1839–1846, 2014.