The Dutch police is now free to use them as spit masks. Unfortunately there are people who like to spit and cough in the faces of the police (and then being charged with weeks in jail).

But I doubt it will work well against coughing because the airflow can just go around it.

LaVision had this great visualisation about the coughing airflow: https://m.youtube.com/watch?v=kYJvU81DKgk