“Which is why masks are useless, and instead we should have spent money upgrading these poorly ventilated spaces, and put in protections for them.”
One of our younger relatives on track to be an engineer did an internship this summer with a cutting edge HVAC company. His bosses/owners of this company have felt that the dirty air being recycled wherever there are sick people or people becoming sick are often the causes of spreading CV~19 and ???? to other patients and staff, exposed to the contaminated/recycled air.
He has discussed this with his girlfriend, a future RN and a female relative finishing her last classes before becoming an RN.
No one in power in hospitals really wants to discuss this problem.
Then, throw another emerging piece of data: Homeless people living outside in the open air are not coming down with CV~19.
Most modern hospitals have taken this into account. They have air exchange systems, they have separate systems for high-risk areas, they use things like filters, and UVC lights, for controlling airborne particles.
My dentist set up a bunch of UVC filters around their office to help keep things clean. I put a UVC light in my A/C system early on in the pandemic, before they got really expensive.