Part 2
Let’s get back to knowing our sunscreens to the core.
Sunscreen and their efficacy are generally marked by SPF, considering the more the better, but what is SPF??
SPF is the Sun Protection Factor. It works as an indicator of its efficacy against the UVB rays of the sun. SPF refers to the amount of UV radiation it takes to produce sunburn when wearing sunscreen in comparison to how much UV exposure it takes for unprotected skin to get sunburned.
SPF measures the quantity of UV radiation, not exposure time. This is because the intensity of solar energy varies throughout the day. For example, you can get roughly the same amount of UV radiation between 9 and 10 a.m. as you would in 15 minutes of early afternoon sun.
Thus, wearing higher SPF sunscreen does not mean being protected for a longer duration. The efficacy highly depends on the reapplication of the sunscreen. It is also said that while going out, at least a shot glass amount of sunscreen must be lathered on, and then an SPF 30 can go well too.
SPF 30 blocks 97% of UV rays, and SPF 50 blocks 98%, but higher SPF offers only small extra protection.
MBH/AB