re: How are your co-workers handling the masks?

It is implemented here. My career is in-line as to why many people are having issues.

Self made masks differ in regards to airflow due to what it is made out of.

Same reason why people are fit tested for n-95 and up. Pulmonary issues can create problems. Not enough oxygen coming in mixing with your blood content can, obviously, create issues.

Some just complain to do so but others do have the inability to receive appropriate oxygen intake to function appropriately.

In my situation (homemade masks allowed) there is such a variance that these situations present themselves frequently.