Human exposure to lead above baseline levels is common. Baseline refers to the naturally-occurring level of lead in soil or dust that is not due to the influence of humans. The highest and most prolonged lead exposures are found among workers in the lead smelting, refining, and manufacturing industries. The primary source of lead in the environment has historically been anthropogenic emissions to the atmosphere. The ban went into effect on February 2, 1996.
Atmospheric deposition is the largest source of lead found in soils.
Lead particles are removed from the atmosphere primarily by wet and dry deposition. The average residence time in the atmosphere is 10 days. However, the number of sites evaluated for lead is not known. All information is taken from the Toxicology Profile for Lead.