Helmets may be designed to withstand an impactful crash, but over time they can wear down.
Factors like sweat, hair oil and chemicals can slowly degrade their inner padding layer made from expanded polystyrene (EPS). Once its glue holds it together it's time for replacement - otherwise your helmet could end up on its last legs!
Motorcycle helmet inner padding plays an essentia... https://michaelbrodiehelmetelover.blogspot.com/2024/10/5-best-glue-for-motorcycle-helmet.html