I had to wear them when working on product on the wafer test floor at National Semiconductor, along with bunny suit, hair/beard net, mask, fingercots or gloves. I'd say I was out there a couple of hours a day on average. Nitride gloves were available for anyone with vinyl allergies. They paid engineers well for the area. I would have quit if I had to wear that shit all day. Oh wait! I quit anyway.