Having been thinking about selling my house soon and only being in it for just over 5 years, I wanted to test for lead. I have reloaded out there and cast bullets along with cleaning brass in an vibrator. Doing some research I found a 3M product called Leadcheck which seemed to be one of the only ones approved by the EPA. It has 8 vials that you break two liquids in the vial, mix them and then rub them on any surface.
I always cast with the garage door open and the side door open and a fan pulling the air out the garage. Reloading is pretty much done when the doors are closed. I tried one place near the entrance into the house on the carpet (yes my garage is carpeted which makes for neat little scars when the lead sprue gets away from me). No lead present. What a relief so far.
Next i tried on the window sill immediately above my casting and reloading bench. Figured if any was there it had to be right on that ledge. Surprise, no lead again.
Actually I was surprised. I expected to find some. the test kit even includes a test patch that when you get a negative response you rub the same swab on that patch and if it turns red then your test is confirmed it was negative.