Published 09 Nov 2023
With temperatures heating up and holidays on the horizon, we take a moment to shine a spotlight on the all-important summer staple: sunscreen. How exactly does it protect us from the sun’s damaging rays and what are some key things to keep in mind when choosing your next sunscreen product?
Sun exposure can either be incidental (think walking to the shops, driving with the window down or having a picnic at the park in part-shade) or prolonged (a day at the beach, working outdoors for extended periods or going on a hike) and, depending on the time of day and intensity, both types can cause damage.
What is UV radiation?
Ultraviolet (UV) radiation is responsible for the sun’s damaging rays, and causes more than 95% of all skin cancers. There are three primary types of UV radiation, and these are classified according to their wavelength. Only two of these penetrate the Earth’s atmosphere:
- UVA: This accounts for most of the UV radiation that reaches the Earth’s surface. UVA rays are able to deeply penetrate the skin and cause cellular damage, premature ageing and also skin cancer. Thing ‘A’ for ageing.
- UVB: Most UVB radiation does not pass through the Earth’s atmosphere but when it does, it can cause sunburn. UVB rays can also damage skin cells and lead to melanoma and other skin cancers. Think ‘B’ for burning.
- UVC: This radiation is absorbed by the ozone layer and atmosphere and does not reach us on the Earth’s surface.
UV radiation emitted by the sun cannot be seen or felt, but we can measure the amount that reaches the Earth’s surface by the UV index and can monitor this in real-time with most trusty weather apps. It is recommended to apply sun-protective measures when the UV index is at three or higher. Don’t be fooled by cool or cloudy days as UV levels can still be relatively high in this weather.
How can I protect myself from UV radiation?
Those living in Australia and New Zealand in the 1980s would remember the iconic and effective ‘Slip, Slop, Slap’ campaign, and know that sunscreen is not a foolproof measure for minimising the effects of sun exposure. These steps are still recommended today but have been expanded to cover five forms of sun protection:
- Slip on a T-shirt or loose-fitting clothing to cover unprotected skin,
- slop on sunscreen*
- slap on a broad-brimmed hat,
- seek shade, particularly in the middle of the day when UV is highest, and
- slide on sunglasses
* ’slop’ underplays the guidance slightly, as sunscreen should be applied liberally and with care and always at the recommended dosage, which for the average adult is 5mL per limb (think a teaspoon amount), front, back and face, covering the neck and ears. It is also recommended to use a broad-spectrum sunscreen rated SPF30 or higher and to use a water-resistant sunscreen if swimming, reapplying at least every two hours throughout the day as needed to maintain protection.
We’ve also prepared some tips for staying safe outdoors this summer.
Which sunscreen should I use?
The range of choices can be overwhelming when standing in the Sun Care aisle, but here is a bit more information to help you decide which sunscreen is right for you.
What does the SPF rating mean?
The Sun Protection Factor (SPF) rating is a globally recognised system that measures the level of protection against sunburn, and more specifically UVB rays. This rating indicates the amount of time that it takes for protected skin (skin that has had the sunscreen applied to it) to redden compared to unprotected skin. For example, when using a product rated SPF30, it will take approximately 30 times longer for protected skin to burn compared to bare (unprotected) skin. It is not a measure of how long the sunscreen will protect the skin for, as is often thought, so it is still just as important to reapply a product with SPF30 as one with SPF50 after the designated time period.
The SPF rating also gives an indication of the amount of UVB rays that a sunscreen will block out.
- A sunscreen rated SPF15 blocks out approximately 93% of UVB rays
- A sunscreen rated SPF30 blocks out approximately 97% of UVB rays
- A sunscreen rated SPF50 blocks out approximately 98% of UVB rays
Sunscreens with SPF30 and above will provide a ‘high’ level of protection and sunscreens with SPF50+ will provide a ‘very high’ level of protection.
Is there an equivalent UVA rating?
There is no such global harmonisation for UVA labelling, and this is measured and communicated differently in different countries. In Australia, sunscreens that provide the required level of protection from both UVA and UVB rays are labelled as ‘broad spectrum’. Without this labelling, consumers cannot be sure that they are adequately protected from UVA rays. Given that both UVA and UVB radiation have been proven to cause skin cancer, it is recommended to use a broad-spectrum sunscreen rated SPF30 or above to ensure you’re getting a high level of protection.
Understanding UV filters
You may see sunscreens labelled as either ‘chemical’ or ‘mineral-based’ and this refers to the type of UV-protective filters that the sunscreen contains. All active ingredients must be declared on sunscreens listed with the Australian Therapeutic Goods Administration (TGA), so you should have a clear idea of the UV filters contained in each product.
Chemical or organic UV filters include tongue-twisting titles like Diethylamino Hydroxybenzoyl Hexyl Benzoate, Ethylhexyl Salicylate and Bemotrizinol. These filters are absorbed into the skin where they in turn absorb UV rays before converting them into heat that is released from the body. Chemical filters work across a wide yet relatively limited range of UV wavelengths. For this reason, most chemical sunscreens use a combination of filters to achieve the desired level of sun protection.
In contrast, inorganic or physical UV filters such as Zinc Oxide and Titanium Dioxide have a microfine particle dispersion which forms a barrier on top of the skin that reflects, scatters and absorbs UV radiation. Because of the nature of these physical filters, they often leave a white or purplish cast on the skin, particularly with sunscreens that have higher SPF ratings. This can be overcome to some extent during formulation by selecting approved nano-materials, combining with ingredients that prevent agglomeration or the clustering of particles and/or by adding pigment to tinted sunscreens.
Some sunscreens will use a combination of chemical and physical UV filters to ensure adequate UV protection without compromising on sensorial properties such as the product’s skin feel, aroma and finish. Because there are so many factors at play when formulating sunscreens, and there is a delicate balance to be struck between efficacy (sun protection), compliance with regulatory requirements and consumer satisfaction (those sensorial properties mentioned earlier), it is always advisable to try a new sunscreen on your skin to check if it is right for you.
Ready to slip, slop, slap?
GMHBA members with eligible AIA Vitality packages can claim their Cancer Council sun-protective products with extras! Waiting periods and annual limits apply. Find out more about AIA Vitality benefits in the fact sheet in your member area.
