Everyone I know staying in hospital always caught pneumonia and many other dangerous infections. My grandmother was taken in for kidneys or eyes and caught 6-8 different serious diseases. She always refused to go to hospital. She hated it.
The air flows from ICU to everywhere and filters need to be cleaned, besides of the inhealthy cold air. I never enter a shop with airco it makes me sick,same for my children. Better open a window and ventilate or leave it closed during the day.

Hospitals are far of clean I know I worked there.