They also want us to prove we're vaccinated which will expose our health information on the cloud in out HR system. I fully intend to fight this and I've emailed American Frontline Doctors. If my department manager isn't willing to fight this I'll be forwarding AFDs documentation. At worse, threaten resignation.
I've worked here for 4 years and I know they can't afford to train someone else with the workload we do. And since I've been in IT nearly all my life I can safely say I can get a job elsewhere with relative ease. (Or perhaps collect unemployment and milk Illinois while I build my own business up, we'll see).
I will add one more bullet in your arsenal:
https://jamanetwork.com/journals/jamapediatrics/fullarticle/2781743
This shows that these mask within 3 minutes will violate hippa laws. On top major health complications can ensue, for which your employer has to bear full responsibility.
It is a medical experiment to wear masks, apart from the fact that physics and biology teaches us these masks are useless to prevent inhalation of particles the size of "viruses".
For participation a medical informed consent is needed.
Ask him to show complete risk analysis and the science behind the requirement.
Start looking around already. Better to act from a position of strength.