Only safe thing is no beard
A thick beard makes it impossible to place the respiratory protection against your face tightly. Factually it is enough with a few days of beard stubble to contribute to lessen the protection factor with 90 procent.
(shows beard equipment)
To achieve maximum effect of a whole- or half protection it is a must to make sure it closes tightly against the skin. Beard and beard stubble creates tiny gaps between the protection and the face, resulting in impure air leaking into the airways. A smoothly shaven face if therefore the only option to maintain the protection factor at its original level, if you are not looking for a more advanced respiratory protection with over pressure.
(graph containing the difference between beard, beard stubble and shaved)