Solar radiation exposure

[Frabjous]

Does one get more biochemical response (tanning, vitamin D production, etc) from continuous compared to discontinuous exposure (for example 1hr vs 4hr of 15min/hr) during a single day. For simplicity assume that solar radiation is constant.

 

[gleem]

For high-energy photons, the biological effect of a large exposure is greater than that of the same exposure spread over a longer time interval, either continuously or in multiple fractions. This is due to the cell's ability to repair damage. The repair becomes more complete as the damage occurs at a slower rate.

Since tanning radiation is ultraviolet, which is also ionizing radiation, I would expect a similar effect. As far as Vitamin D production, I do not know.