You would be hard pressed to find much difference between one of the diy jobs and a hospital grade system (although you might need to add a UV light) assuming y

You would be hard pressed to find much difference between one of the diy jobs and a hospital grade system (although you might need to add a UV light) assuming you use the same filters. The reason is, it's not about having some perfect seal with dirty air going in one side and sterile air coming out the other. It's about recirculating the same air over and over through the filter catching a little bit more particulate matter each time.