By "air vents", I'm assuming you mean extraction ventilation ???
As being a newbie salon space renter I would say it is ABSOLUTELY essential. My first couple of months I did not have any form of extraction. However, once I began getting busier I noticed how much dust I was producing and how "full" my nose was starting to feel (sorry guys if you are eating your dinner !!)
I am now waiting for my new table and extraction system to arrive so I can rid myself of all this dust.
Personally I think it is a very important piece of equipment.
Just my opinion