I live in the country and do all of my shooting at an abandoned gravel pit. I went to visit my son in the city and we went to an indoor shooting range (first time for me). What do they use for a backstop and how do they harvest all the spent lead? Is there a high enough concentration of lead vapor in the air to be a health hazard.

Most indoor shootin' ranges don't allow high-power rifle shooting because of the "overpenetration" problem.

Lead vapor is removed via a very expensive system that uses oil in some capacity. I am sorry, but I don't remember much beyond that.