Sun Protection...6 Things To Know About Your SPF

For some of us, summer is just beginning and for others (we see you, Arizona) it has been here for months already.  Summer is when our inboxes are flooded with questions on SPF and sunscreens, though we really should be wearing SPF daily - even in the winter.  

Every year, it seems the sunscreen choices become even more overwhelming and the buzz words keep coming.  Physical SPF. Chemical SPF, SPF10-20-30-40-50-60-70-100, Broad- spectrum, Reef-safe, Ocean-safe, is often hard to know what you really need.

We've highlighted a few important things to understand when it comes to making a sunscreen choice.  Feel free to contact us with any questions you might have, or comment below.

Let’s start with the basics:

1) UVA vs UVB rays  Sunlight reaches our atmosphere (and our skin) in two forms: Ultraviolet A (UVA) and Ultraviolet B (UVB) rays. UVA rays are long wave and they penetrate deep into the dermis, which is technically 2 layers below skin surface. This type of radiation accounts for 95% of the UV radiation that reaches earth. Yikes.

UVA rays do not cause sunburn but they do cause premature aging, wrinkling and they affect the immune system negatively. UVA exposure is associated with a higher risk of developing melanoma. Further, UVA rays are equally prevalent at all times of day throughout the year, unlike UVB rays.  

UVA-UVB-UVC raysUVB rays will burn your skin, which plays a key role in the development of skin cancer. UVB ray intensity varies but tends to be strongest in the summer between 10am and 4pm. However, UVB rays can be strong in the winter, as you know if you ski or snowboard, and other seasons AND on cloudy days, so there really is no opportunity to let your guard down (except at night!).   Bottom line – they both cause skin cancer so we want to block as much of both of them as possible. There is also a 3rd form – UVC but they don’t reach us. Finally, one thing NOT to worry about.

Up to 80% of solar UV radiation can penetrate light cloud cover so that means on cloudy still need sunscreen.

2) SPF (Sun Protection Factor)  SPF protects against UVB rays. The exact # tells you what % of UVB rays will be blocked and it not linear (or intuitive).

  • SPF 15 blocks 93% of UVB rays 
  • SPF 30 blocks 97% of UVB rays 
  • SPF 50 blocks 98% of UVB rays

SPF alone does nothing against UVA rays. This fact surprises many people.  But fear, not the solution is below (hint: broad spectrum).  When it comes to SPF, a higher number may not always be better. The problem with high SPFs comes down to two key points: 1) consumer misunderstanding, and 2) additional chemicals used to achieve a marginally-higher SPF. 

A product with SPF50 effectively blocks 98% of UVB rays. SPF100 will block 99%. Only an additional 1%. The misuse and misunderstanding comes about because people think “Great, I’ve got SPF 100 so I am good to bake in the sun all day from 10-4 without reapplying.” But really, that isn’t the case as sunscreen is usually only effective for a few hours. Further, a higher SPF does not mean the product offers any protection at all against UVA rays. As a result, these people probably would get some sunburn and may absorb a LOT more UVA radiation. Strong protection requires reapplication, which many people just don’t do (we are guilty of this too). 

Higher SPFs require higher amounts of sun-filtering chemicals than lower SPFs and some have been linked to tissue damage and potential hormone disruption. See #5 for more info on this.

Additionally, the ingredients used to block UVA and UVB rays can counteract each other so a really high SPF is blocking most UVB rays but may offer little UVA protection. This isn’t a widely known fact – you can find it on the EWG website when investigating the difference between physical and chemical SPFs.

Lastly on the SPF get the SPF advertised you are supposed to use a full ounce – or a full shot glass – on your body.  So that bottle of sunscreen that is 6 ounces? Should only last six applications. Six. Not six months or two years. Facial sunscreens obviously last a lot longer because much less is needed for full coverage.

3) Broad Spectrum  There is some confusion about broad spectrum, so let's clear some of that up. First of all, Broad Spectrum protects against UVA AND UVB rays. The bottom line is you always need to use a broad spectrum sun protection product.  Always.  SPF only measures protection against UVB rays, not UVA and while preventing sunburn might be our primary objective, we also want to limit premature aging, wrinkles and exposure to dangerous UVA rays, which are linked to skin cancer.  

4) Physical Filters / Blockers  Physical filters form a layer on your skin, blocking the rays from penetrating. There are two primary physical filters for sunscreen, zinc oxide and titanium dioxide. Zinc oxide physically blocks UVA and UVB rays and is one of the only ingredients that effectively blocks both (it is naturally broad spectrum). You know it is a physical blocker because of the thick, white, sometimes chalky, layer on your skin. Not always the most attractive, but some brands (including Honua) have worked to come up with facial sunscreens that are not very whitening. When it comes to kids, the more zinc the better because you can always tell when kids are covered!  Zinc oxide is widely regarded as ocean/reef safe so it has become our go-to at Honua.

Titanium dioxide is another physical blocker of sun rays.  We find it safer than UV-absorbing chemicals (see #5 below) but we prefer zinc as our option.

5) Chemical Filters / Blockers  Chemical filters in sunscreen absorb the suns rays rather than block them. They penetrate the top layer of the skin and work to absorb the rays, before your skin does.  These chemicals can include PABA-derivatives, cinnamates, salicylates, benzophenones and others. There are studies that say they penetrate the skin, act as hormone disrupters, or that they routinely generate free radicals due to sensitivity to light. You will also be able to find studies that say these chemicals are perfectly safe or that they are better than the alternative – sunburn and risk of skin cancer. That’s undoubtedly true, but we prefer to avoid them since we can.

Additionally, many regions, including Hawaii, have banned sunscreens containing oxybenzone and octinoxate because the chemicals have been shown to damage/kill coral reefs.  That alone is enough for Honua to say "no" to all chemicals in our SPF.

6) Spray sunscreens are so convenient. Aren’t they the best?  Well, yes, they are convenient. Unfortunately, convenience does not always equal good (i.e. porta-potty comes to mind.) The issue is two-fold: 1) Sprays can be harmful when inhaled so don’t use sprays around kids and take caution when using them yourself, and 2) Sprays are often poorly applied, with much of the actual product flying off in the wind or not being applied thickly enough. Yup, that is right, user error. Applying a thick coat of lotion/cream sunscreen is less convenient but more effective. 



We look forward to helping you protect your skin! 


Wishing you good health and lots of Aloha !












The Honua 'Ohana















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