Everything I've seen from best advice, the method of contamination, and those that have figured out how they got a high level is: hygiene. If you smoke, drink on the range, don't wash your hands enough, etc. then you are at higher risk, even outdoors. Organic lead compound vapor in the air isn't so dangerous. Landing on stuff, including your hands, then ingesting that, is quite dangerous.
Reloaders are much higher risk than shooters.
Casting is so high risk they should go ahead and do at least annual checkups forever to monitor it.
I know several folks who had to stop their shooting for a year or two due to lead levels, changed how they approached everything when they came back.
Me: did enough dangerous chemical work back in college* I guess so got used to procedures, and have a below-average lead level when blood tested for it. I don't even use special anti-lead wipes, etc. Just normal hand washing or wipes when in austere environments, is quite enough.
*I did printmaking, spent long periods in a room full of nitric acid vapors, enough I got sick from it, then made them get me a proper-filter respirator, and scrupulously used it from then out.