Flawed UV Advice

It turns out that some of the advice we’ve been getting about UV protection is wrong. We are advised that “no protection” is needed on days when the peak UVI is less than 3. But our recent study shows that on such days, the total UV dose can exceed that needed to cause visible damage (i.e., erythema – or skin reddening) to fair skin by a factor of 5 or more. It’s true that UV doses can be much higher on days when the UVI exceeds 3 (they can exceed the threshold for skin damage by a factor of 30 in mid-summer), and advice to protect is even more important then. But at mid-latitudes about 10% of the total annual dose occurs on days when the peak UVI is less than 3. So if we follow the current advice on those days, we increase our risk of skin cancer. The “no protection” messages should be removed from public advisories when the peak UVI is less than 3, except for the few days when the daily dose is insufficient to cause skin damage. It all depends on how long you will be outdoors in the sun. Sun protection should be advised for extended outdoor periods all year round at mid latitudes. Read all about it here. And an interview with Kathryn Ryan of Radio New Zealand is available here