The silver content in ores to be smelted was concentrated by dressing, the washing away the lighter non-productive fraction in water, thus polluting the waterways. The high consumption of charcoal decimated woodlands. Smelting furnaces issued large quantities of lead fumes, containing lead and lead compounds. Lead compound emission levels within the workspaces of the haciendas exceeded modern standards on occupational safety and health. For every kg of silver smelted, five to ten kg of lead in lead compounds was disseminated from the furnace area into the surrounding air, to be deposited around each working area close to the furnaces or entrained by the flue gas out of the chimney stacks, to ultimately settle on the soil, streams and surfaces within and without the hacienda. Additional lead compounds would be found as fugitive emissions within each refining hacienda, which at times harboured the Spanish owners or overseers, their indigenous workers, slaves and their families.