As we have already discussed, UVA light has a longer wavelength than UVB and can therefore penetrate deeper into the skin, making it the prime cause of skin ageing; along with tissue damage, mutation, and skin cancer as seen with UVB exposure.
Due to this longer wavelength it is also able to penetrate through glass windows and can still affect the skin, such as when driving a car. This was highlighted in studies looking at American truck drivers, who tend to drive with their windows wound up in air conditioned cabs, who showed more extensive photodamage on the left side of their faces, (the side nearest the window).
As UVA penetrates deeply it does not cause sunburn like UVB light. This causes a problem for scientists as the fact that UVA radiation does not cause reddening of the skin like UVB means it cannot be measured within the SPF testing; hence there is no standard international measurement for the blocking of UVA radiation, despite it being important that sunscreens block both UVA and UVB.
In fact, 24% of people we surveyed admitted that they didn’t know whether UVA and UVB filters were an important consideration in their choice of sunscreen, a confusion possibly emphasised by a lack of a widespread standard measurement.
However, a (4 star) UVA star rating was created by Boots the Chemist in 1992 for use in the UK, which has since been adopted by most leading sunscreen manufacturers to become the basic industry standard recognised worldwide. This current system for rating UVA protection was updated in February 2004 and goes from 1 star to 5 stars, representing a ratio of UVA protection relative to UVB protection, the SPF. It is recommended that you always look for a sunscreen with the maximum star rating.
The UVA wavelength range is further split up as UVA1 (340–400 nm) and UVA2 (320–340 nm) and recent scientific studies have revealed that it is the longer wavelength UVA1 rays that cause photoageing as they penetrate deepest into the tissues of the skin (2). However, most sunscreens currently available in high street shops do not protect against UVA1, despite promoting themselves as having generic “UVA filters” to prevent ageing etc.
With the availability of higher SPF rated sunscreens, meaning individuals will spend larger amounts of time in the sun without burning from the UVB rays, concerns have now been raised within the medical community as to the adequacy of the comparative UVA protection contained in these products; as people may be subject to greater UVA exposure and damage than if they stayed out for a shorter period of time with a lower SPF product.
Our survey revealed that whilst 64% of people stated that they always bought a sunscreen containing a UVA filter; of that same group only 28% always bought one claiming a UVA1 and UVA2 filter, with 15% saying that they never even checked for both filters.