Sunscreen. . . What does it all mean?
We all know we’re supposed to wear sunscreen, and with so many different types on the market it can be difficult to determine which one is best for you? Let alone what all of the confusing numbers, stars and abbreviations mean. So let us try and break it down so you know what to look for.
First of all, what are we protecting our skin from?
Ultraviolet radiation (UV) emitted by the sun, and there is not just one type. . . Oh no. . . There are two types we need to be aware of (well actually three but the third is not concerning), UVA, UVB and UVC.
UVA - Accounts for 95% of the radiation reaching the earth's surface, it can pass through clouds and glass due to its longer wavelength and can penetrate deep into the dermal layer, causing DNA mutations that can lead to skin cancers, photo ageing and pigmentation changes. It is present throughout the year at equal intensity.
UVB - Cause the skin to become red and burn, accounts for 5% of radiation and vary in intensity depending upon the season. Plays a large role in the development of skin cancers.
UVC - These rays are filtered by the ozone layer and therefore do not reach the earth's surface.
So this is what we are protecting our skin against, but what should you be looking out for when considering purchasing a sunscreen? What do the stars, +++, numbers and letters actually mean?
SPF (sun protection factor) refers to the potential to block UVB rays only, this does not include UVA rays. The number denotes the time the skin will redden when exposed to the sun whilst wearing sunscreen versus time without sunscreen. Eg. If your skin reddens after 10 minutes in the sun, then theoretically it will take the skin 300 minutes to redden whilst wearing an SPF30 sunscreen. I say theoretically as these values are determined under laboratory conditions, not real world. Sunscreen becomes less effective over time, therefore it is recommended to reapply every 2 hours or after swimming or excessive sweating
Most sunscreens these days also offer protection from UVA radiation and can sometimes be referred to as “broad Spectrum” simply meaning they protect against both UVA and UVB radiation. However the level of protection from UVA is represented in slightly different ways depending upon where it originates.
The letters UVA represented inside a circle is a European marking denoting that it meets EU recommendations and is at least one third of the SPF value. In some instances it can also receive a star value between 1 and 5 with the higher values offering the greatest protection. The British Skin Foundation recommends using an SPF with a minimum of 4 star rating.
In addition, you may have noticed a PA value followed by a scale of between + and ++++, this is the ‘protection grade of UVA’ and seen on international sunscreens. Again, the higher values offer the best protection.
The final consideration when purchasing sunscreen is whether to choose chemical (AKA Organic) or physical (AKA Inorganic) based SPF? Both types work by absorbing UV radiation preventing damage to the skin. It is an outdated myth that physical sunscreens reflect all UV radiation, in fact they only reflect 5% of radiation. So what is the difference?
Physical - Although still technically a chemical, physical sunscreen ingredients include Zinc oxide and titanium dioxide. These have a thicker less oily consistency and can create a white cast (can lead to inadequate application). They are well suited to sensitive skin types as they cause fewer allergic/irritant reactions.
Chemical - ingredients include Avobenzone, octocrylene, oxygen zone, octisalate (amongst others). These tend to have a thinner consistency and often offer higher UVA protection, therefore are well suited to individuals prone to hyperpigmentation and ageing. Can be irritant.
Of course you can also get sunscreens that are a mix of physical and chemical ingredients aiming to get the best of both worlds.
So with all of this in mind it still leaves the burning question (no pun intended). . . how do you choose a sunscreen? Well . . . Ideally the higher the protection the better, but ultimately it is the one that you will use. . . it won't work if it is still in the bottle, I do however hope that this will help you to narrow down the choices.
Stay safe in the sun.