A Few Rays- Calculate how long your sunscreen lasts.
Confused by SPF’s? It’s easy to calculate how long you will be protected by using the following process.
To Calculate SPF protection:
First estimate from your own experience how long it takes your unprotected skin to feel burnt. In the case of a person with very fair skin, this can be as little as 10 minutes in strong sun, where ‘unprotected skin’ would suffer from pinking or mild burning. This is known as ‘burn time’.
Using this formula: Substitute the value for your own estimated ‘burn time’, and multiply by the SPF stated on your sunscreen packaging – and that is the duration of protection the product claims to offer.
In the above equation, a 10 minute burn time (fair skin) is extended to 300 minutes (five hours) by using an SPF 30 sun screen.
For serious outdoors and sports people, you will want to choose long lasting sunscreen that is capable of ‘maintaining an effective SPF’ for the entire time you are exposed to sun. This is especially true for sailors in windy, wet and strong sun conditions.
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