How to choose a sunscreen – SPF myths and misconceptions

 

 

UV radiation from sun exposure is the greatest risk factor for developing skin cancer.  Here in Australia dangerous melanomas are the third most common types of cancer diagnosed. 
Simple sun protection measures including daily use of a broad-spectrum sunscreen can reduce you and your family’s risk of developing skin cancers later in life.  If this is not compelling enough to encourage you to protect yourself, see our earlier post on UV photo ageing.  Wrinkles! Argghhhh

 

 
Our Cosmetic Nurse Kristie breaks down the jargon and myths surrounding sunscreen use.
 
“What does SPF even mean?”

SPF is an acronym for Sun Protection Factor and is a measurement of how effectively a sunscreen will protect the skin from UVB rays (it does not measure UVA, this is important! More on this later).

Confusingly, it talks about time e.g. if it takes 10 minutes to burn without cream, applying an SPF 15 means it will take approximately 150 minutes to burn (a factor of 15 times longer).  THIS DOES NOT MEAN YOU CAN STAY IN THE SUN LONGER OR THAT YOU CAN GO LONGER WITHOUT REAPPLYING.  Sunscreen should always be reapplied after 2 hours to ensure continuous protection.

Misleading I know.

“So, what SPF should I be using?”

The SPF (Sun Protection Factor) scale is not linear, in that an SPF 30 is not “twice” as protecting as an SPF 15.  In fact, SPF 15 blocks 93% of UVB rays, SPF 30 blocks 97% of UVB rays and SPF 50 blocks 98% of UVB. The difference from an SPF 15 to SPF 30 is only 4%.

“So why do I need a higher SPF?”

Flip it around and think about what you are letting through.

SPF 15 (93% protection) allows 7 out of 100 photons through. SPF 30 (97% protection) allows 3 out of 100 photons through. That’s twice as many skin damaging photons!

“I don’t need sunscreen because I’m not outdoors?”

Not true.  UVA, which is responsible for ageing of the skin and contributes to skin cancer formation can pass through glass.  And incidental sun adds up.  Walking to the train, sitting in the window, driving.  So you don’t need to be “outside” to be exposed.

I always tell people to invest in a broad-spectrum product containing SPF 30-50 that they like enough to wear every single day.

Why?

The Anti-Cancer council recommends that sunscreen is required on days when the UV index is 3 or greater (typically in the warmer months between 11-3 pm), which is the threshold at which the UV is strong enough to damage the skin.  HOWEVER, we are creatures of habit and I find in myself and many of my patients that if your skincare routine is not just that, a ROUTINE, then things go to the wayside and before you know it, it’s mid-September, 12 noon and you find yourself in a café without sun protection!

A broad-spectrum sunscreen is important as SPF measures only UVB and we know UVA is a big culprit in causing skin damage.  A broad-spectrum sunscreen will protect against both UVA and UVB.

“What is the UV index?”

It’s “sciency”.  There are a LOT of variables that can influence the amount of UV reaching us.  But scientists are all over this and we highly recommend everyone download the Sun Smart App which will tell you what the maximum UV index for the day is forecast to be and when it is at its highest.

Thank you science!

“Do I need to reapply?”

Yes. All sunscreens need to be reapplied after two hours to maintain their SPF role. Are you going to reapply your sunscreen over your makeup at lunchtime in the middle of winter when you’re in the office? Probably not. And that’s ok.

1/ Because the UV index is low then

2/ Most of the damage from UV comes from accumulated exposure. Our skin is like a data bank for sun damage! So having your base SPF on for incidental sun when you leave the house helps reduce your lifetime UV exposure and associated damage. Unless your office desk is next to a window. Then see my earlier point about UVA passing through glass.

The reason to reapply is often unclear?  Is it wiping off? Does it have a time-limit of efficacy? Does it breakdown?

The answer is all of those things.  You will touch, rub, wipe, smear, and remove some of your SPF protection without noticing.  If you are sweating, exercising, swimming, etc we are pretty clear on the fact that your sunscreen will not withstand that.  Reapply.

Some chemical sunscreens do break down when exposed to sunlight. This is less of a concern with mineral (zinc or titanium oxide) sunscreens but this does mean that if you are outdoors, in the sun, your sunscreen DOES have a lifespan and it DOES breakdown.  It lends merit the argument that if you are in an office, away from all windows and will have minimal incidental sun (and don’t touch your face AT ALL) then your sunscreen MAY last longer.  I would definitely encourage you to reapply if you are planning on spending significant time (>1 hour) outdoors.

“I heard Nanoparticles were dangerous?”

They’re not.  The worry here was that the smaller nanoparticles which allow higher concentrations of our physical blocks containing zinc and titanium dioxide to be used in creams and still feel lovely and light on the skin were able to be absorbed though the skin and enter our bodies and cause harm.

This is not proven. The current evidence is that these particles do not penetrate the skin and remain on the surface as intended so the risk is negligible.  If applied to damaged or compromised skin there can be some penetration of the outermost layer of skin but they are not absorbed systemically (i.e. they don’t circulate throughout the body).   Be more concerned about inhaling spray sunscreens! Stay away from light sprays that flow with the wind and avoid these on the face.

“But what about Vitamin D?”

According to the Cancer Council sensible sun protection does not put people at risk of vitamin D deficiency and several studies have shown that sunscreen use has minimal impact on Vitamin D levels over time.  Incidental exposure, a few minutes most days is all most people require for adequate Vitamin D production.  If you are deficient in Vitamin D increasing UV exposure is not recommended and you should speak with your GP regarding supplementation.

We hope this clears up some common excuses people use for NOT applying sunscreen every day.  There are no excuses!  We KNOW skin cancer is directly related to UV exposure and we KNOW sunscreen protects us from this.  

 

There are so many nice, easy-to-use sunscreens available these days for every budget.  If you need a hand choosing one, call us today on 9039 5644 and book a consultation with our Cosmetic Nurse Kristie and we will get you on the right track.

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Kristie Phillips RN (Cosmetics Nurse)

View posts by Kristie Phillips RN (Cosmetics Nurse)