No offence intended, but I'm thinking this is a "joke" thread, that the OP is pulling our leg. Tumble outside then immediately change clothes? (Sheldon Cooper ain't that paranoid). I don't know any reloaders that are this frightened of some dust exposure once or twice per month (if it was several times per day, maybe). The amount of lead in the dust is infinitesimal, too little to be considered. But there are several methods mentioned above to stay "safe" when tumbling brass .

There are many household chores that are more "toxic/dangerous" than tumbling brass, and stay away from bullet casting. Most city air is more dangerous than tumbling dust and in rural areas do the farms spray toxic materials (or any chemicals) from airplanes?

If the OP is offended by my observation, I apologize.