Not getting into a helmets vs not debate here, take it as given that I wear one. I change every 3 years or so on the basis of the say-so evidence above. Having accepted the argument of the benefit of wearing, I’m not waiting to find out if the 3 year suggestion is true or not by crash testing my own head, £45 or so over 3 years is about 30p a week which I’m perfectly willing to pay just in case the argumentation is sound.
That said – be interested to see why Met think 8 years?
(oh – and from a scientific pov I suspect that UV light will make the polystyrene brittle and less deformable)