What is the difference between SPF 30 vs SPF 50 sunscreen to protect against the harsh Australian sun?
First, how harsh is the Australian sun?
Very! As illustrated in the map below, areas with extremely high levels of UV are highlighted in red and pink. It only takes a few minutes to get sunburnt during the Australian summer. Adequate protection is essential, all year round, as soon as UV index reaches or exceeds 3.
Second, many consumers don’t realise that SPF30+ complies with the older 1998 standard, whilst SPF30 and SPF50+ comply with the latest standard from 2012. This new standard incorporates two significant improvements.
The most crucial improvement is in the UVA protection arena: UVA is primarily responsible for skin ageing and skin cancer. The 1998 standard did not impose any substantial protection against UVA. This omission has been addressed by the 2012 standard.
The second improvement, and most relevant to this article, is the significant increase in claimable SPF. Many SPF 30+ (1998 standard) or SPF30 (2012 standard) products have a Sun Protection Factor of 30 only. Whereas SPF 50 (+) sunscreens have a Sun Protection Factor of 60 or greater - doubling the protection, compared to SPF30 or SPF30+ sunscreens.
When applied correctly, sunscreen is designed to reduce skin burn-time by the claimed SPF factor. In other words, if unprotected skin burns in 5 minutes, it will burn in 150 minutes when protected by SPF30 sunscreen and in 300 minutes when protected by SPF50+ sunscreen. By design, SPF50+ is doubling the protection, compared to SPF30 or SPF30+.
Now then, how is absorbing 1.3% more UV rays doubling the protection?
It is easy to confuse transmission and absorbance, which are two different things. As the graph below illustrates, UV absorption increases by 1.3% when going from SPF30 to SPF60, but the UV transmission rate is cut by half, and SPF protection is doubled.
The most important fact to remember is: what matters is not the UV rays that don’t reach the skin (absorbed) but those which do (transmitted).
To use a food analogy: A 98% salt-free product contains 2% salt, and a 99% salt-free product contains 1% salt. The difference between the two products is not 1% “salt-free”, but double the salt load, which can be the difference between life and death for some.
The damage that UV light does to our skin works in the same way: it’s the UV light reaching our skin that matters, so using SPF 30 versus SPF 50 sunscreen halves the protection.
Our tip: most people don’t apply the dose used to determine sunscreen SPF performance. Our recommendation is to apply sunscreen liberally, let it dry, and then reapply the same sunscreen. This repetition will help ensure a sufficient load of UV filters onto your skin, thus reaching the performance required under our harsh Australian sun.