Parece que o benefício da Vitamina D atrás de um vidro não existe (vidros comuns filtram o UV-B) é que continua a existir risco de cancro de pele (em excesso os UV-A fazem igualmente mal):
https://www.independent.co.uk/life-style/health-and-families/features/can-you-get-a-tan-and-absorb-vitamin-d-through-a-window-a6895626.html
Citando:
"The sun emits ultraviolet (UV) A, UVB, and UVC rays. The latter is the most damaging, but is filtered by the atmosphere and doesn’t reach the earth’s surface.
Vitamin D is produced by the body when the skin is hit by UVB rays, with 7-dehydrocholesterol being the resulting chemical. But most glass windows block this wavelength meaning you can't reap the health benefits.
(...)
A 2010 US study into skin cancer found that people who spend a lot of time driving a car each week are more likely to develop skin cancers on the left side of the body – which is the window side in North American cars.
Data on 1,000 patients showed that 74 per cent of patients with malignant melanoma, an aggressive form of skin cancer, had tumours on their left sides, according to the study by researchers at the St Louis University, the New York Times reported."
Link to news on this study;
http://www.nytimes.com/2011/04/05/health/05really.html
