Richard, rather than me trying to understand the physics involved in UVI derivation so as to calculate safe and effective UVB doses for my skin for different elevations of the sun, I will reformulate my question starting with a statement: Through repeated skin cancer checks and blood tests during the past 9 years I have established how many minutes of sunshine exposure my body requires to receive a safe and effective UVB dose when NIWA’s real time UVI at my location is between 9 and 10. Am I correct in assuming that I should double the time of sunshine exposure to receive the same safe and effective UVB dose when NIWA’s real time UVI is between 4 and 5 at my location, or is UVB intensity not a simple linear function of real time UVI?
Yes, to a reasonable approximation, UVB = 7 x UVI. The approximation fails for very lie UVI, but works ok for UVI of 3 or more. I wrote a paper on that relationship a few years ago. It’s published in photochemical and photobiological sciences (PPS).
Thanks Richard, That makes sense. I assumed the relationship is not simple linear but your answer provides a guideline for regulating UVB exposure for optimum health and minimum risk of causing or aggravating skin cancer.
Richard, rather than me trying to understand the physics involved in UVI derivation so as to calculate safe and effective UVB doses for my skin for different elevations of the sun, I will reformulate my question starting with a statement: Through repeated skin cancer checks and blood tests during the past 9 years I have established how many minutes of sunshine exposure my body requires to receive a safe and effective UVB dose when NIWA’s real time UVI at my location is between 9 and 10. Am I correct in assuming that I should double the time of sunshine exposure to receive the same safe and effective UVB dose when NIWA’s real time UVI is between 4 and 5 at my location, or is UVB intensity not a simple linear function of real time UVI?
Hi Michael
Yes, to a reasonable approximation, UVB = 7 x UVI. The approximation fails for very lie UVI, but works ok for UVI of 3 or more. I wrote a paper on that relationship a few years ago. It’s published in photochemical and photobiological sciences (PPS).
Thanks Richard, That makes sense. I assumed the relationship is not simple linear but your answer provides a guideline for regulating UVB exposure for optimum health and minimum risk of causing or aggravating skin cancer.