A while back a reader asked me what filters existed that covered specifically the UVA2 spectrum.
I have to admit to you, that its such a geeky technical sunscreen query that it made my heart sing.
So after doing a bit of research (because that’s what I do well), this blog answers this query. Honestly, I am a bit surprised at the outcome.
What is UV radiation?
I find it useful to put into context what exactly UVA2 radiation is.
As the bulk of UVA radiation is UVA1 (340-400nm), I hypothesised that there is no specific filter targetting UVA2.
But this is not correct. When I plotted out the maximum absorption of UV radiation by UVA and UV filters, it appears that UVA2 is covered by default because its in that “sandwich” zone of 320-340nm.
UVB filters provide declining absorbance of UV radiation in the UVA2 region, as demonstrated by Diethylhexyl Butamido Triazone (DBT).
UVA filters providing increasing absorbance of UV radiation in the UVA2 region as demonstrated by BEMT.
Which filters provide the best overall protection in UVA2?
Its an exercise in vanity to judge filters on a standalone basis because most sunscreens (90%+) have more than one sunscreen filter. (Zinc Oxide is the only filter that tends to appear by itself).
I’d rank the absorbance of UVA2 radiation in the following declining order.
BEMT> DPDT> DT> DHHB=MBBT=Zinc Oxide=DHBT>Avobenzone
Or this can be demonstrated as follows:
Abbreviations used:
BEMT (Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine)
DPDT (Disodium Phenyl Dibenzimidazole tetrasulfonate)
MBBT (Methylene Bis-Benzotriazolyl Tetramethylbutylphenol)
ZnO (Zinc Oxide)
DBT (Diethylhexyl Butamido Triazone)
Avobenzone (Butyl Methoxydibenzoylmethane)
DHHB (Diethylamino Hydroxybenzoyl Hexyl Benzoate)