I'm equipping a lab room (~3x5 meters) that's supposed to be used for DNA and RNA extractions. I know about the basic safety precautions when working with RNA and DNA extraction (fresh gloves, labcoat, separate workstations/pipettes, RNase-free workspace etc), but it is my first time seting up this sort of things so I'm a bit unsure how strict I have to be about some of these things, so my question might seem a bit silly/stupid to some but here it goes anyways.
The question; I want to buy UV-lamps to clean out old DNA in the environment so I don't contaminate my fresh samples. I don't work in any hoods. I have a downdraft ventilation table and a bench that both stands along one wall on which I'll be Working on. I wonder if it is enough to just have one UV-lamp that covers my working area, or should I buy enough UV-lamps that cover the entire room (since I'm not working in any hood -> risk for airborne contamination)? Or is it over-kill to cover the entire room? I don't want to spend to much money.