During 1999, the Mexican Health and Environmental
authorities in conjunction with the smelter company
and under the surveillance of nongovernmental organizations
started a vast program based on an official
decree from the Government of the State of Coahuila
and several official regulatory agencies of the Mexican
Federal Government2. The program consisted of technological
and engineering changes in smelter complex
practices to decrease metal emissions and several cleaning
and remediation activities. Among them, the most
important was the collection of more than 100,000 Kg
of dust containing high concentrations of metals in
streets, highways, roofs and houses using high efficiency
vacuum machines; this action was important as an
environmental intervention house by house. Additionally,
more than 100 families from the neighborhood
with the highest levels of lead pollution were relocated
to sites far away from the smelter. The program was
carried out within a 3 km radius of the center to the