Sunblock 101: SPF, Sunscreen vs Sunblock, Active Ingredients Explained

Summer has been with us for more than a month now and I hope everyone is having their daily dose of SPF! I have to admit, sometimes it's a hassle to apply sunscreen and skipping it is the easiest thing to do. But there are times when I come to my senses and realize that I have to give my skin some love and protect it from the harmful rays of the sun.  I have said this before and repeating it now, it is of grave importance to put sunscreen every single day or else your old age skin will have to pay for it.

Here are some must-knows about your sunblocks.

UVA vs UVB

UVB stands for Burn. It is the primary cause of sunburn. UVA stands for Aging. It goes deeper into the skin and causes premature photoaging and also sunburn at some extent. It is more potent in generating free radicals and causing oxidative damage to DNA and macromolecules.

Both UV rays are linked to skin cancer with UVB being the more carcinogenic between the two as it induces direct chemical damage to the DNA. UVA rays, however, is more abundant in sunlight and indirectly damages our DNA by producing free radicals whenever it is absorbed by other molecules which are endogenous photosensitizers.

SPF and UVA-PF

Sun Protection Factor is a measure of protection against UVB
The amount of UVB radiation blocked by SPF 15 is 93%, SPF 30 is 97%  and SPF 50 is 98%. Going beyond SPF 50 does not add a whole lot of protection. 

UVA stars (PA in North Asian countries) is a measure of protection against UVA. It is recommended to use sunblocks with UVA★★★ or PA +++ which delivers 60-80% protection from UVA rays.

With the statements above, we can simply say that SPF is for UVB rays while UVA stars/PA is for UVA rays.

Sunscreen vs Sunblock

Sunscreen and sunblock differs in the kind of protection it offers. The former being chemical and the latter, physical. It is both effective in blocking both UVA and UVB rays through different mechanisms.

Sunblock

• physical kind of protection
• The usual ingredients: zinc oxide & titanium oxide
• It leaves a white cast on the skin when applied
• It is good for sensitive skin

Sunscreen

• chemical kind of protection 
• usual ingredients: oxybenzone, avobenzone, octisalate, octocrylene, homosalate and octinoxate.
• No white cast
• Sensitive skin may react to some of its ingredients (like PABA)

A small table of the common ingredients in sunblock/sunscreen and their sun protecting properties

Application
Recent studies have shown that the following mode of application is effective: apply 20 minutes before sun exposure and reapply once within 1 hour.

Here are some promising products to try.

So there you have it! Whether you are simply running some errands or you are enjoying your favorite summer destination, remember to never skip the SPF! Love and protect your skin!

For comments, questions, and suggestions feel free to comment down below.

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