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What Does SPF 30 Mean?

As per its SPF formula, what does SPF 30 mean?

The formula for calculating SPF is =
The time it takes for sunscreen covered skin to burn divided by The time it takes for bare skin to burn

So, as per this formula, a sunscreen with SPF 30 means…
A SPF 30 sunscreen offers 30 times more protection than when you had no sunscreen.

For consumers, what does SPF 30 ‘actually’ mean?

Here is what consumers need to know about SPF 30:

SPF 30 blocks nearly 97% of UVB rays from affecting the skin.
SPF 30 lets 3% of the sun’s UVB radiation enter the skin and affect the skin.
It blocks 97% of the radiation.
SPF 50 lets 2% of the sun’s UVB radiation enter and affect the skin.
Since SPF 30 lets 3% of UVB enter the skin, in contrast to SPF 50’s 2%, SPF 30 is 50% less effective than SPF 50.

Is SPF 30 ENOUGH?

SPF measures the protection the sunscreen offers from UVB radiation.

But what about protection from UVA??
Remember, we also need protection from the sun’s UVA.

So always use a broad-spectrum sunscreen.

Broad-spectrum sunscreens offer protection against both UVA and UVB.

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How often should we reapply SPF 30?

All sunscreens, irrespective of the SPF number, should be reapplied every 2 hours.

If we don’t apply sunscreen every 2 hours, it’s the same as not wearing any sunscreen.