I've heard reports that the traditional medical groups are really coming down on tanning salons, saying that no amount is healthy.
and I've also heard the opposite from some hygienist/frutiarian types that will actually recommend artificial tanning over D supplementation in times of no possible sun exposure.
I think with the first, there is some misunderstanding of how the sun/artificial light will successfully push toxins through the skin but not necessarily be the source. Perhaps the artificial light creates some kind of mutation with this process, but even so the medical community links traditional sun exposure (minus sunscreen) with skin cancer as well. Whereas it is clear that the peoples who have maintained their traditional diets do not succumb to such things, even with the supposed shifting harmful UVs. That said, the frutarian types tend to have dried out alligator type skin also, so eating high fats/minerals from animal foods, is probably more necessary than just abstaining from modern toxins.
Theres a few different types of models for equipment, again according to these new medical rulings, there isn't much difference for the higher priced versions. I've done one of them where you stand up and the whole cylinder lights up and circulates air. Its actually kind of a wonderful experience, but I've never really thought to go back for it. Well, actually I did but just got lazy and held out for this spring, and the natural rays are working their magic.