UVA and UVB: What's the Difference and Why Does It Matter?

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Two types of ultraviolet radiation reach your skin every time you step outside: UVA and UVB. They sound almost identical, but they behave differently, cause different kinds of damage, and your sunscreen needs to handle both. Here's how they work and what it means for the sunscreen you choose.

UVA: The One You Don't

UVA rays have a longer wavelength and penetrate deeper into the skin, reaching the dermis. Unlike UVB, you won't feel UVA doing its work. There's no immediate sting or redness. Instead, UVA contributes to premature skin ageing: wrinkles, loss of elasticity, and uneven pigmentation that can show up years later.

The tricky part is that UVA is far more constant than UVB. It's present year-round, on cloudy days, through autumn and winter, and it passes through glass. That means you're exposed to UVA during a winter drive, at a window-side desk, or on an overcast morning when the sun doesn't feel strong at all. In Australia, where UV levels are consistently high even outside of summer, this matters. A grey sky in July doesn't mean the UV is off duty.

Why You Need Both Covered

A broad spectrum sunscreen helps protect against both UVA and UVB radiation. In Australia, the TGA requires that all primary sunscreens provide broad spectrum protection and display this clearly on the label. So if you're buying a sunscreen with an SPF 30 or above from an Australian retailer, you should see "broad spectrum" on the packaging.

How Sunscreen Filters Work

There's a common idea floating around that some sunscreens "reflect" UV rays while others "absorb" them. The reality is simpler than that: both mineral filters (like zinc oxide and titanium dioxide) and chemical filters work primarily by absorbing UV radiation and converting it to small amounts of heat.


Mineral filters do scatter and reflect a small portion of UV, but absorption is the dominant mechanism for both types. The practical differences between mineral and chemical sunscreens come down to things like skin feel, suitability for sensitive or reactive skin, and formulation, not a fundamentally different way of handling UV.


If you'd like to dig deeper into how mineral and chemical sunscreens compare, click the button below:

MINERAL VS. CHEMICAL

Broad spectrum sunscreen

Every sunscreen in the Maxiblock range provides broad spectrum SPF 50+ protection, which means UVA and UVB are both covered in a single application. If you're after something lightweight for your face, a tough formula for a long day on site, or a gentle option for the kids, broad spectrum protection is built in across the board.

What This Means for Your Routine

Understanding the difference between UVA and UVB should shape two habits:

  • Wear sunscreen even when the sun doesn't feel harsh. UVA is present on cloudy days, through windows, and in cooler months. If UV levels are 3 or above (which in Australia is most of the year), broad spectrum sunscreen is worth applying.
  • Reapply every two hours, or after swimming and sweating. SPF protection reduces over time. This applies regardless of whether you're worried about sunburn or longer-term UVA exposure. Two hours is the general guideline. If you've been in the water, towel off and reapply.

The rest is straightforward: sunscreen, hat, sunnies, shade where you can find it. The UV doesn't care whether it's a beach day or a Tuesday morning school run.