Sunscreen: How much is enough?

By Heather Woolery-Lloyd

Last week in my Sunscreen 101 blog I told you everything about how sunscreens work, but I neglected to tell you the most important thing; How to properly use sunscreen! So, today I am going to do just that.

Correct application of sunscreen is essential to achieve the right amount of protection. Studies show that most people do not apply enough sunscreen. One European study showed that students applied 1/5 the recommended sunscreen quantity. The correct quantity of sunscreen for the body is 2mg/cm2.  What does that actually mean? Well to put it in regular terms, to achieve this quantity, you would have to apply one ounce of sunscreen to properly cover the body. One ounce would fill a mall shot glass.

The average bottle of sunscreen is around 6 ounces. If reapplied, every 2 hours, a bottle of sunscreen would last 1-2 days at the beach. Similarly, for the face, approximately 1.2gm of sunscreen is required to achieve the 2mg/cm2 dose.

Most women use significantly less than that for daily use. When we use insufficient amounts of sunscreen to cover a given area, we are not getting the correct SPF. One study found that most users probably achieve an SPF of  50% of the expected SPF because inadequate sunscreen quantities are applied. An SPF 30 turns into a 15…or even worse an SPF 15 turns into a SPF 7.  Realistically, we are not likely to change the quantity of sunscreen application in everyday use.

For most women 2mg/cm2 of sunscreen for daily facial use may be perceived to be “too heavy”. Increasing the SPF from 15 to 30 for a product used daily is one easy solution to address this problem. It is important to note for extensive sun exposure, such as at the beach and other outdoor events, generous sunscreen application is a must.

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