If you swallow a bit of skin from your lips by mistake, or you could not find it, or it is too difficult for you to take it out of your mouth, so you swallow it with your saliva, your fast is valid.

Inhaling the mist breaks the fast. Therefore, it is not permissible for one who is fasting to use a nebulizer during the day in Ramadan, except in cases of necessity, and if he uses it he breaks the fast.