There is well established evidence that exposure to ultraviolet radiation (UVR) from the sun can lead to skin cancer. Application of sunscreens as part of your daily routine is an effective method of sun protection when used with a combination of other protective measures. Aerosol sunscreens are not recommended.
Health effects from solar UVR
ARPANSA and other national and international health authorities, including the World Health Organization have assessed that overexposure to ultraviolet radiation (UVR) causes eye damage, sunburn, tanning and other skin damage that can ultimately result in skin cancer.
This damage can be prevented by using good sun protection, including sunscreen that is at least SPF30 or higher, broad-spectrum and water-resistant.
The Australian Standard for sunscreens allows a sun protection factor (SPF) rating of up to 50+, which filters 98% of UV radiation in comparison to SPF30, which filters 96.7%. SPF50 and SPF50+ sunscreens will provide excellent protection as long as they are applied properly.
Sunscreen effectiveness
There is more to sun protection than just sunscreen. No sunscreen provides complete protection against UVR.
It is recommended that sunscreen is used as part of your morning routine on days when UV is forecast to reach 3 or above.
Sunscreen also needs to be carefully applied and reapplied:
- Apply sunscreen 20 minutes before you go outside and again every two hours.
- Use a generous amount of sunscreen – the average adult needs 35ml for one full body application, which is the equivalent of more than half a teaspoon to each arm and the face, and just over one teaspoon to each leg, the front of the body and the back.
- Check sunscreen is within its use-by-date and store below 30°C.
Aerosol sunscreens
Aerosol sunscreens use a type of dispensing system which creates a mist of liquid. The quantity of propellant in aerosol sunscreens dilutes the amount of sunscreen dispensed and increases the amount of sunscreen product needed to achieve adequate SPF coverage.
In 2020 Queensland University of Technology produced a report on the testing and evaluation of aerosol sunscreens:
Aerosol sunscreen labelling advises to 'apply generously' or 'use liberally', but there are concerns that users do not apply sufficient sunscreen which can result in serious sunburns. Laboratory testing (2020) of different aerosol sunscreens show that it requires between 4-14 seconds per limb and 29-98 seconds for a full body application.
More recently, in 2021 Griffith University produced a report that found the effectiveness of applying aerosol sprays is impacted by wind conditions:
Laboratory testing (2021) into aerosol sunscreen application efficacy found environmental factors such as wind dramatically lowered the ability of aerosol sunscreen to effectively provide protection against UV radiation. As much as 93% of the sunscreen can be lost in 20 kph winds which occur 67-87% of the time between 9am-4pm during summer at Australia's most popular beaches.
Avoid using aerosol sunscreens and stick with creams and lotions for UV protection. Even saturating your body with an entire can of the product may not provide the level of protection you expect.
SPF rating
A sunscreen’s SPF rating indicates the level of protection provided against UVR. It’s the ratio of the UVR dose someone would receive without sunscreen to that received with a carefully applied sunscreen. Sunscreens sold in Australia must be labelled with an SPF of at least 4 to the highest rating of 50+.
SunSmart recommends choosing a sunscreen labelled SPF50 or SPF50+ that is also broad-spectrum (will filter out both types of UV radiation) and water-resistant.
Sunscreen protection of SPF50 for a fair skinned person provides 50 times more protection to the exposed skin; if the skin reddens without protection in 10 minutes, then applying SPF50 sunscreen provides protection for up to 300 minutes if applied correctly.
The purpose of using sunscreens is to reduce UVR exposure, not to extend the time spent outside in the sun. Sunscreen should be reapplied every two hours, whether the label says to or not. This is because sunscreen can be easily wiped off, lost through perspiration and is often applied unevenly in the first place. Always reapply after swimming or water sports.
The following table shows the amount of UVR blocked out for a given SPF rating. Broad spectrum sunscreen with SPF30 blocks 96.7% UVR and a SPF50 blocks 98%.
| SPF | % UVR Blocked |
|---|---|
| 4 | 75 |
| 8 | 87.5 |
| 15 | 93.3 |
| 30 | 96.7 |
| 50 | 98 |
Sunscreens are available as either a primary or secondary sunscreen.
- Primary sunscreens are a product to be used to protect the skin from UVR.
- Secondary sunscreens have a function other than sun protection whilst still providing some protection of the skin from UVR i.e. moisturisers, make-up, lip balm, anti-ageing or anti-wrinkle creams.
The composition of sunscreens
Chemical sunscreens absorb UVR while physical sunscreens reflect and scatter UVR to protect the skin. Sunscreen can be purchased as a cream, lotion, spray or gel. Choose one that best suits your skin type and activity, and that you find easy to apply. If you have sensitive skin or have a reaction to a product, there are fragrance-free or sensitive formula sunscreens available.
There has been concern regarding nanoparticles being absorbed by the skin and harming living tissue. A Therapeutic Goods Administration (TGA) review concluded that ‘the current weight of evidence suggests that nanoparticles do not reach viable skin cells and remain on the surface of the skin and the outer layer of the skin that is composed of non-viable cells’.
In Australia, sunscreens can only be sold if they are listed on the TGA Australian Register of Therapeutic Goods (ARTG) and are compliant with the Australian Standard for sunscreens. Sunscreen active ingredients and maximum concentrations must be approved by the TGA as being both safe and effective.
The Australian sunscreen standard
The Australian Standard for sunscreens limits the maximum protection claimed on the labelling of sunscreen products to SPF50+.
Sunscreen manufacturers are unable to claim the terms ‘sunblock’, ‘waterproof’ and ‘sweat proof’ as these terms are considered to be potentially misleading. The maximum water resistance claimable is four hours for SPF30 and above.
Protection messages
For best protection, we recommend a combination of sun protection measures:
- slip on some sun-protective clothing that covers as much skin as possible
- slop on broad spectrum, water resistant SPF50 or SPF50+ sunscreen. Put it on 20 minutes before you go outdoors and every two hours afterwards
- slap on a hat – broad brim or legionnaire style to protect your face, head, neck and ears
- seek shade
- slide on some sunglasses – make sure they meet Australian Standards.
Cancer Council Australia provides further protective advice through national, state and territory Sunsmart programs and activities.
Links
- World Health Organization provides international advice on sun protection
- Cancer Council Australia provides advice on preventing cancer in Australia
- Australian Standards AS/NZS 2604 Sunscreen products – Evaluation and classification
- Therapeutic Goods Administration ‘A review of the scientific literature on the safety of nanoparticulate titanium dioxide or zinc oxide in sunscreens’
-
'Report: Testing and Evaluating Aerosol Sunscreens, November 2020'
