•

In some cases, Vitamin D has even been linked to a decrease in the risk of developing some cancers.

It is widely accepted that the time needed to expose your skin to the sun in order to gain enough Vitamin D, is much less than the time you would spend sunbathing to produce a tan or suffer sunburn.

Because the device would only operate during the week; when people are typically working, it would only be used for these short breaks you might or might not take as the case may be.

According to The British Association of Dermatologists, '...the range of vitamin D intakes required to ensure maintenance of wintertime vitamin D status of 20 to 40 year old adults, considering a variety of sun exposure preferences, is between 7.2 and 41.1 micrograms/day.'

This figure seems to equate to around 10-15 minutes in the noonday sun. See here and here for suggestions.

If that period of time is the maximum one should spend in the sun without protection whilst the sun is at its strongest, then during cloudier days, that time would supposedly increase.

As this project is born of personal interest without any view to market, I will fabricate a system based on the little information that I have. In an ideal situation, this project could warrant further research, professional advice and rigorous testing.

Presently however, I hope to simply build a rough working prototype, based very loosely on general information that I gather together regarding the health implications of UV.

In terms of translating that 10-15 minute daily recommendation into the system, each LED could represent 5 minutes. Therefore, in the strongest rays, at the hottest period in the day - between 11am-3pm, only 3 LED's would illuminate. If it were cloudier or outside of those hours, more LED's would activate relative to the UV levels.

The prototype will be suited to my personal situation - being located in London, being fair skinned with light hair. This would vary if you were in a country with warmer climes and had darker skin, which would increase time for the skin to burn and absorb Vitamin D.

The complete cycle takes place only once within a nine hour window, between 9am and 6pm.

1. The user arrives at work at 9am and sits at their desk with the device plugged into their computer via USB.

2. The computer is connected to the Internet.

3. An RSS feed containing UV data is processed through a sketch and uploaded to the device once every 10 minutes.

4. If UV levels reach a certain point during the day, the device will give off a signal, perhaps by vibrating or buzzing.

5. There is also a series of LED's running along the device - one LED signifies an alloted amount of time. Depending on the data, the appropriate number of lights turn on - the user spends as much time outside as it takes for all lights to go out.

6. The user unplugs the device and goes outside in the sun.

7. A UV sensor on the device registers an increase in UV levels to match the data and a timer starts, beginning the countdown of LED's.

8. If UV levels drop below a certain point (i.e. the sun goes behind clouds) for less than or equal to 3 minutes then the timer pauses and the LED's begin to flash as a warning.

9. If UV levels remain below a certain point (i.e. the user goes into a shop) for more then 3 minutes then the timer remains paused and a loud buzzer sounds, prompting the user to complete the cycle.

10. At this point the user can go outside in the sunshine again, or manually pause the device.

11. If the user chooses to pause the device, they can complete the cycle later in the day at a more convenient time. The LED's will flash to signify this paused state and it will give off a short, sharp buzzing noise once every 30 minutes until it is re-started. If the user returns to the desk while the device is paused, they may wish to update the data in case the weather has changed and they can no longer complete the cycle as UV levels have reduced. If this is the case, the LED's will react accordingly, letting the user know how much time, if any, they need to still complete.

12. Once the cycle is completed, the LED's will flash in a pattern and turn off.

13. If the cycle is for some reason not completed by 6pm that day, then the device will reset itself.

14. If the user exposes the device to extra UV rays once it has completed its cycle and within the nine hour window, the buzzer will sound until UV levels are reduced accordingly for up to one minute. This is to prevent over exposure to the sun and a lax attitude to work during the summer.