Be wary of any purifier that does not clearly state the micron capture size of their filter. They vary from 2.5 micron size, .3 micron and down to .003 medical grade. The smaller the micron capture size the more effective a filter is at removing all contaminants from the air. IQ Air has medical grade on Amazon if you want a hospital type of air filter but I assume other brands are also available with medical grade filters.
This particular air purifier is ranked as one of the best on numerous sites. It has multiple filter options you can purchase for different performance and cost of filtration. I purchased one myself about a month ago and have been quite happy so far.
That said, I purchased mine from The Mother Ship, new, on sale for $360. It was a steal. It’s currently being offered at that same price. With one-day Prime shipping and free returns.
This “sale” from Woot is insulting.
https://www.amazon.com/Blueair-HEPASilent-Technology-DualProtection-Allergies/dp/B085B4V3DP/