I have a UV AB meter that can measure UV A and B light intensity in microWatts/(centimeters squared). In direct afternoon sunlight, I measure UV AB at about 3000 microWatts/cm^2. In the shade of the same afternoon, I measure UV AB at about 600 microwatts/cm^2.
I've been told by dermatologists to avoid being in direct sunlight in the afternoon. So is there a specific limit in UV intensity (watts/area) where dermatologists would recommend not being exposed to?