Do you turn off your engine at the gas station?

I'm not sure why either, except to say before vapor capture systems were developed for both car and gas station hoses the smell of fumes always filled the air. With these improved safety devices the signs remain but I'm not sure the reason does. I do know the safety reasons behind grounding yourself before fueling to avoid static discharge as with the infamous "sweater lady" static discharge incident. I do turn my engine off, but I usually leave the generator running.