3. When uvb is present, you can make sufficient vitamin d quite quickly
This would suggest you would want sunscreen for longer exposures, or with much uva exposure. And could get vitamin d from a briefer exposure pre sunscreen.
I can’t say how completely sunscreen blocks vitamin d however.
Actually, it seems I was wrong. I thought it was just UVA, but uvb also causes melanoma.
I’d delete the above comment if I could. The main point that you can get vitamin d from short exposure without sunburn is correct, but I was incorrect on the risk. But he fact I was wrong about uvb and melanoma also makes me think I may be incorrect on the risk of uva during periods without uvb.
1. Uva is the cause of most skin cancer
2. Uvb generates vitamin d and sunburns
3. When uvb is present, you can make sufficient vitamin d quite quickly
This would suggest you would want sunscreen for longer exposures, or with much uva exposure. And could get vitamin d from a briefer exposure pre sunscreen.
I can’t say how completely sunscreen blocks vitamin d however.