I think you can get such air cleaners from medical/surgical suppliers. I have seen such air cleaners used in medical labs and operation theaters.
I remember one such unit (IQ Air, Swiss) came to us for repair / servicing. If you are in Lahore, Neela Gumband surgical market is a place to check. Otherwise HEPA filters are commonly available (not sure if that is the thing you need)
I will check with someone I know and let you know if I get some information on where to buy it.