Here is one way lead particals get into the air at a range... when the bullet strikes the metal backstop millions of microscopic lead particals are released into the air... when you have proper air handeling equipment it will keep this dust at the end of the range...
http://ca.youtube.com/watch?v=YIL1VSc86dM
At about 1 min into this clip you can see a prime example of microscopic particals... lead, unburnt gunpowder, some primers also contain lead so all of this is entering the air your breathing indoors... it can be hazerdous to fire outdoors with the wind blowing in your face too..
http://ca.youtube.com/watch?v=G0VjdI_S_HM
http://ca.youtube.com/watch?v=YIL1VSc86dM
At about 1 min into this clip you can see a prime example of microscopic particals... lead, unburnt gunpowder, some primers also contain lead so all of this is entering the air your breathing indoors... it can be hazerdous to fire outdoors with the wind blowing in your face too..
http://ca.youtube.com/watch?v=G0VjdI_S_HM