Sun Protection Explained: What SPF Really Means for Your Skin

Sun protection shouldn’t be confusing – and yet somehow it is. Myths circulate, new “rules” appear online, old misconceptions resurface, and advice ranges from almost true to completely misleading. Add to that the recent sunscreen recalls in Australia, and it’s understandable if you’re questioning what, or who to trust.

The reality is much simpler and far more helpful. Once you understand what SPF actually measures, what it doesn’t, and how to use sunscreen properly, everything becomes easy to understand. My hope is to cut through the noise so you can protect your skin with confidence.

Let’s begin with the fundamentals: what SPF really tells you.

What SPF Actually Measures (and What It Doesn’t)

SPF, or Sun Protection Factor, measures how well a sunscreen protects your skin from UVB radiation – the rays responsible for sunburn and a major contributor to skin cancer. That’s all SPF tells you.

It does not tell you how much protection you’re getting from UVA, the deeper-penetrating wavelength that drives long-term damage: uneven pigmentation, collagen breakdown, and the visible signs of photoageing.

Another piece of the puzzle is how SPF is tested. The number on the label reflects lab conditions using a generous, perfectly even application. Real life rarely looks like that. Most of us apply far too little.

And if you’ve ever seen your skin under our Observ Diagnostic System with sunscreen still on, you’ll know how easy it is to miss areas: the hairline, jawline, ears, eyelids, and sides of the neck. Over time, these small gaps add up. It’s a visual reminder that sunscreen works – but only when it's applied correctly.

Understanding this – SPF relates to UVB, while UVA requires a different level of protection through a broad‑spectrum formula that shields the skin from both UVB and UVA wavelengths – along with the importance of consistent and proper application –  makes sunscreen much easier to get right.

Next, let’s look at the types of light we’re actually protecting against.

UVA, UVB – and Where Infrared Fits In

When we talk about sun protection, we’re really talking about different wavelengths of light, each affecting the skin in its own way.

UVB

The rays responsible for sunburn. UVB doesn’t penetrate deeply, but it can directly damage DNA and is strongly linked to skin cancer. SPF measures UVB protection.

UVA

The deeper-penetrating rays. You don’t feel UVA in the same immediate way, which is why this type of sun damage can creep up on us, and over time it contributes to collagen breakdown, uneven tone and visible ageing. UVA is ever present every day of the year, even those cloudy days and travels through glass – meaning you’re exposed indoors and in the car.

Infrared (IR)

Not ultraviolet, but still worth knowing. Infrared contributes to heat in the skin, which can trigger redness or pigmentation, particularly in people prone to melasma, post-inflammatory hyperpigmentation or flushing. Sunscreen doesn’t block heat, which is why topical antioxidants like Vitamin C and Vitamin B3 (niacinamide) serums and creams, can help support the skin’s resilience.

Alongside skincare, physical protection still matters. Shade, hats and protective clothing significantly reduce heat and UV exposure – something no sunscreen can do alone.

Broad-spectrum protection makes sense when you understand how differently these wavelengths behave. Preventing a burn is important, but protecting the deeper structures of the skin matters just as much for the youthful longevity of the skin. 

SPF 30 vs SPF 50 – What the Numbers Really Mean

There’s ongoing debate about whether SPF 50 is meaningfully better than SPF 30. Once again, the key is remembering what SPF measures: UVB protection only.

Here’s the comparison:

• SPF 30 filters about 97% of UVB

• SPF 50 filters about 98%

A higher SPF gives you more UVB coverage, but that doesn’t automatically make it the best choice for every day. The important part is choosing a broad‑spectrum sunscreen and matching the SPF level to your day. If you're mostly indoors, a broad‑spectrum SPF 15 may be all you need. On days when you’ll be outside for longer, SPF 30 or 50 simply gives you a stronger UVB buffer. And importantly, SPF 50 isn’t “stronger” or harsher – it simply allows less UVB through.

Ultimately, the number – whether it’s SPF 15, 30 or 50 – matters far less than whether the formula is broad‑spectrum. SPF tells you how well a product protects against UVB, but without UVA protection, you’re only shielding part of the suns harmful wavelengths. 

A broad‑spectrum SPF 15 like ESK Zinc Shade can be a great everyday option for general indoor or incidental exposure – especially if you’re mostly inside and not spending long stretches in direct sunlight. For days when you know you’ll be outdoors for longer, an SPF 30 or 50 like Synergie Skin's Uber Zinc Body is ideal for a stronger UVB buffer.

The key message? Broad‑spectrum is non‑negotiable. Sunscreen without UVA protection doesn’t offer the full protection your skin needs for long‑term health and premature ageing prevention.

Which brings me to another point that often causes confusion. 

How long can you stay in the sun?

Many people also assume that SPF tells you how long you can stay in the sun. It’s often said that SPF 50 gives “two hours of protection,” or longer if the product is water‑resistant, but SPF doesn’t measure time at all. It measures how much UVB light is filtered under ideal lab conditions.

Everyone’s burn time is different, too. Someone very fair might burn in ten minutes, while a deeper skin tone may tolerate thirty minutes or more before redness appears. Sunscreen helps extend that window, but it doesn’t create the same level of protection for everyone – and everyday factors like sweating, rubbing, or incomplete application reduce it further.

So rather than thinking of SPF as a timer, it’s more accurate to think of it as a UVB filter. Broad‑spectrum protection does the heavy lifting, and the SPF number simply helps you match your sunscreen to the kind of day you’re having.

Even with correct application and reapplication, sunscreen doesn’t mean you can safely stay in the sun for long periods. On high‑UV days, seeking shade an covering up is still the safest choice.

With the numbers clarified, let’s look at the most common reason sunscreen underperforms in daily life.

The Real Reason Sunscreen Fails: How (and When) You Apply It

Most people know sunscreen works – the real misunderstanding is when to use it. Many assume sunscreen is mainly for summer or only needed when it’s sunny. That makes sense if you’re thinking about UVB.

But UVA is present all year, from early morning to late afternoon, even on cloudy days, and it penetrates glass. It’s the wavelength responsible for most long-term damage, which is why daily sunscreen makes such a visible difference over time.

How you apply it matters too:

• Use enough. For the face, chest and neck, aim for a 20-cent piece amount or two generous finger lengths.

• Cover the small areas. Hairline, ears, eyelids, under the jaw – these are the spots most often missed.

• Reapply. Especially when swimming, sweating or spending hours outside.

• Make-up with SPF isn't always broadspectrum. It sounds like the easy option, but your foundation may not provide the adequate protection your skin needs. 

Applied well, sunscreen works beautifully. Applied sparingly or inconsistently, its protection diminishes quickly – particularly against UVA.

Now let’s clear up another common question: does the type of sunscreen matter?

Chemical vs Physical Sunscreens – Facts, Not Fear

There’s a lot of chatter online about chemical and physical (mineral) sunscreens, and much of it is unnecessarily hyped up. Here’s the simple version.

Chemical sunscreens

Absorb UV light, then disperse and neutralise the energy so it doesn’t harm the skin.

Physical/mineral sunscreens

Use minerals like zinc oxide or titanium dioxide to scatter and reflect UV light.

Both chemical and physical sunscreens are regulated in Australia.

Both protect your skin, the important choice depends on whether you like the texture enough to use it daily.

What matters most:

• Choose a texture you enjoy – you’re far more likely to use it consistently.

• Both types offer broad-spectrum protection.

• Mineral often suits sensitive, reactive or redness-prone skins.

• Chemical formulas tend to feel lighter and layer well under make-up.

There’s no universally “best” sunscreen – only the one you’ll apply generously every morning.

How Sun Damage Shows Up

You don’t always see sun damage as it’s happening – but your skin certainly does. It’s a slow, steady build-up that often only becomes noticeable years later.

Here’s what’s happening beneath the surface:

• UVB causes redness, heat and inflammation – the classic sunburn you feel.

• UVA works quietly in the background, breaking down collagen and elastin and showing up later as fine lines and uneven tone.

• Heat (including infrared) can aggravate pigmentation and redness, even if you don’t burn.

Most of what we think of as “ageing” – fine lines, wrinkles, uneven tone, redness and changes in texture is actually the skin showing the cumulative effect of UV exposure over time.

With 80% of skin ageing directly attributed to uv exposure, daily protection isn’t about today’s sun, but how your skin will look years from now when it's protected consistently. 

Myths to Ignore (Because They Won’t Help Your Skin)

Sunscreen is one of the most studied skincare products we have, yet myths persist. Here are a few I hear often in clinic:

• “I don’t need sunscreen in winter.” It's worth repeating, that UVA, the wavelength responsible for long‑term ageing, is present all year and penetrates clouds and glass. If you're outside, near a window, or in the car, you're getting UVA exposure.

• “Chemical sunscreen is harmful.” Both chemical and mineral sunscreens are safe and regulated.

• “Darker skin doesn’t need sunscreen.” Deeper skin tones can still burn and develop pigmentation and UV-related damage.

• “I’ll become vitamin D deficient.” Sunscreen prevents burning, not all UV exposure. Daily life still provides adequate incidental UV for most people.

• “My foundation has SPF, so that’s enough.” A bonus, not a replacement.

Understanding the truth behind these myths makes sunscreen choices and daily use much simpler.

How to Choose the Right Sunscreen for You

With so many sunscreens available, choosing one can feel overwhelming. A few simple guidelines make it easier:

• Choose broad-spectrum for UVA + UVB protection.

• Opt for SPF 50 for a more added protection on high UV days.

• Pick a texture you enjoy. Comfort increases consistency.

• Match your lifestyle. Water-resistant options for outdoor or active days.

• Mineral or chemical? Choose the one you’ll actually use.

If you're unsure, we have a great selection of sunscreens and we'd be happy to help you find a formula that suits your skin and routine.

In Summary – What You Need to Remember

• Choose broad-spectrum sunscreen to protect against both UVA and UVB.

• Use enough. A 20-cent piece amount for the face and neck.

• Don’t miss small areas. Hairline, ears, eyelids, under the jaw.

• Reapply. Especially when sweating or swimming.

• Use additional physical protection. Hats, shade and protective clothing help reduce heat and UV load.

Your Daily Sun Protection Habit Starts Here

When it comes to sun protection, I always come back to the same simple truth: your skin thrives when you protect it consistently. And while sunscreen is essential, my advice will always be this — seek shade whenever you can. Staying out of the full strength of the sun does more for your skin than any product ever could. 

Personally, I gravitate toward mineral, zinc-based sunscreens. They offer reliable broad-spectrum protection, feel calm on the skin, and suit most skin types — especially if you’re prone to redness or sensitivity. Used daily, and paired with hats, shade and protective clothing, they’re one of the best ways to keep your skin healthy and resilient.

If you’re not sure where to begin, I’ve included some of my favourite sunscreens below.

If you'd like personalised advice or help choosing the right formula, I’m always here to help.

Our Favourite Sunscreens

Available in our Clinic and Online:

• Synergie Skin ÜberZinc  – calming, zinc-based, broad spectrum sunscreen that feels lightweight and moisturising and ideal for all skin types.

• Environ RAD UVA + UVB Broad Spectrum SPF15 – a beautifully wearable daily sunscreen enriched with antioxidants.

• ESK Zinc Shade – a lightweight broad spectrum mineral option that sits comfortably over your serums and creams and is perfect under make-up.

• Synergie Skin Über Body – Provides physical, mineral sunscreen with UVA/UVB broad spectrum solar protection.

About the 2025 Sunscreen Recalls

In 2025, several sunscreens – from small indie brands to big household names – were recalled after independent testing showed they offered far less protection than advertised. Some products labelled SPF 50+ were performing closer to SPF 4.

The recall attracted a great deal of attention and naturally caused concern among consumers. It also raised important questions around testing, stability, raw material suppliers and how SPF values are verified.

It’s important to separate these manufacturing or regulatory issues from the effectiveness of sunscreen itself. A well‑formulated, properly tested sunscreen remains one of the most reliable tools we have for protecting skin from UV-related damage.

If anything, the recalls were a valuable reminder of why strong oversight matters – and they’ve already prompted improvements in testing and industry standards.

Importantly, none of the sunscreens we stock in clinic were affected by the recall.