What event significantly reduced environmental exposure to lead?

The phase-out of leaded gasoline stands out as a significant event that dramatically reduced environmental exposure to lead. Lead was commonly added to gasoline to improve engine performance and reduce knocking. However, this practice led to widespread lead pollution, primarily from exhaust emissions, contributing to elevated blood lead levels in the general population, particularly in urban areas.

By removing lead from gasoline, a major source of lead emissions was eliminated. This regulatory change resulted in a dramatic decrease in atmospheric lead concentrations, contributing to substantial public health improvements, including lower rates of lead poisoning and associated neurological damage in children. As a result, public health campaigns and policy reforms around lead reduction have focused heavily on the removal of leaded gasoline, making it one of the most impactful changes in environmental health concerning lead exposure.

In contrast, other choices address various environmental protection measures and policies, but none had the direct and profound effect on lead exposure levels as the elimination of leaded gasoline.