Personal protective equipment (PPE) are products that have the function of safeguarding the person who wears them or in any case carries them with them, from health and safety risks. Furthermore, by law, they must carry the CE mark, which indicates compliance with the essential health and safety requirements established by Community standards. One of the biggest problems is determining when personal protective equipment needs to be replaced. Some devices have an expiration date, others are disposable, still others require constant monitoring by the worker of the state of wear in order to replace it if it is no longer suitable. For example: a respiratory device must be replaced when the operator notices particular difficulty in breathing; on the other hand, it will be necessary to replace glasses when the operator detects that the images are no longer perfectly sharp.