It is popular belief that winter sun exposure can be harmful, being the
cause of or contributing to the appearance of several diseases, mostly
related to the upper respiratory tract, sinuses or cerebral. Some
doctors are too in favor of this theory, for which I haven't so far
found a scientific explanation.
Is the spectrum of the sun radiation different in winter when compared
with summer?
Apart from herpes virus simplex are there any known virus susceptible to
this kind of radiation?
Do you thing this theory might have some ground to stand on?
Please unser me if you have any data concerning this matter.