Face masks are great for protecting your skin from harsh weather conditions, pollutants, and allergens. However, not all face masks are created equal. Some masks can be more effective than others.
If you feel like the mask is no longer providing adequate protection from the elements of the environment or it's been damaged in any way. When it is dirty, when it has been worn for more than 3-4 hours a day when the mask can’t be fitted properly, or if it is causing problems like breathing difficulties.