Sunscreen basics – SPF, UVA, UVB and Australian Regulations

Untitled-1 I think when living in Australia it’s very important to understand how sunscreens work and why you need to use them. We have an estimated 128,000 new cases of skin cancer every year. This post is a very basic guide to sunscreen where I won’t be going into a lot of detail such as chemical vs physical or the debate on cancer, but instead explaining how sunscreen works and what the information provided to us means.

The difference between UVA and UVB Rays 

UVB rays

This is the portion of the suns UV spectrum that are wavelengths in the range 290 to 320 nanometres. UVB rays are responsible for causing those nasty red burns. A good way to remember this is by thinking of it as ‘UV-Burning‘ rays. UVB rays only account for 5-10% of solar radiation.

UVA Rays

This is the portion of the suns UV spectrum that are wavelengths in the range 320 to 400 nanometres. UVA rays are what leads to premature ageing and skin cancer, as it penetrates deeper into the skin. A good way to remember this is by thinking of it as ‘UV-Ageing‘ rays. UVA rays account for 90 to 95% of UV radiation that reaches us.

Susan and Jeanne are twins aged 61. Susan (right) spent as much time as she could in the sun tanning and smoking whereas Jeanne (left) tried to avoid UV exposure.

We also have UVC rays, which are the strongest. But thankfully they are absorbed by the ozone layer.


UVB Protection

Many of us are very aware of the SPF listed on the bottle of sunscreens, but what does it actually mean? SPF (sun protection factor) is a measure of the UVB protection, so how much it protects you from burning. The SPF is calculated with this complicated formula below:


I won’t get too much into it, but this takes into account various things and, according to Wikipedia, shows that we can’t layer on different sunscreens to get extra protection. For example, we can’t use two SPF 5 sunscreens to get an SPF of 10.

SPF 50+ has become available in Australia in recent years, but it’s important to note that anything over that value doesn’t provide a significant increase in protection.

Sunscreens are often listed as SPF50+ or SPF30+, so what does the ‘+’ mean? Anything that is listed as SPF50+ MUST have an SPF of 60 or higher and anything that’s listed as SPF30+ MUST have an SPF of 31 or higher.

UVA Protection

Australian Sunscreens

We don’t have a specific measure of UVA protection like Europe and Asia, instead we have the term “Broad Spectrum”, which tells us a sunscreen protects against UVA rays. As of 2012, the standard for UVA protection in Australia was increased by Standards Australia. This meant that UVA now has to increase with increase SPF. According to the “Sunscreen Standard AS/NZS 2604:2012 Regulation impact Statement“, SPF50+ would have 10-20 times the protection against UVA radiation than an SPF30+ sunscreen.

Asian and European Sunscreens 

Most of Asia utilises the PA  system, which tells consumers exactly how much UVA protection there is. Whereas most of Europe utilising the PPD (Persistent Pigment Darkening) system, which also measure UVA exposure. Generally, it is recommended that you have a sunscreen with at least PA+++ for every day use. Below is high the PA and PPD system compares, so you know how to read your sunscreen bottles. It’s important to note than note all countries allow the labelling of PA++++. Such as at this time, Korean sunscreens can only be labeled as high as PA+++.

  • PA+ = PPD 2-4
  • PA++ = PPD 4-8
  • PA+++ = PPD 8
  • PA++++ = PPD 16 and up

Tips for full protection

  1. Many sunscreen labels say “4 hours water resistant”. But you should still reapply every 2 hours for maximum protection.
  2. The “every 2 hours” rule is in regard to cumulative sun exposure. So if you apply it in the morning and take 30 minutes outside to get to work, then you don’t need to apply again on your way home unless the sunscreen has rubbed off.
  3. You need to apply 1/4 teaspoon to your face in order to get full protection
  4. Sunscreen should not only be used alone and it’s important to ensure you are also wearing protective clothing (listed as UPF50+) and seek shade
  5. The SPF listed in makeup is often not what you actually get when you apply it. So don’t rely purely on foundation SPF

Further Reading


5 thoughts on “Sunscreen basics – SPF, UVA, UVB and Australian Regulations

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