From the Summary: "The Administrator of the Environmental Protection Agency (EPA), under a court order to review the National Ambient Air Quality Standard (NAAQS) for lead, proposed to revise the standard on May 1, 2008, reducing it from 1.5 micrograms per cubic meter (μg/m3) to within the range of 0.10 to 0.30 μg/m3. The proposal's publication in the 'Federal Register' will begin a 60-day public comment period. The agency must promulgate a final standard by September 15, 2008. NAAQS are standards for outdoor (ambient) air that are intended to protect public health and welfare from harmful concentrations of pollution. If the Administrator ultimately strengthens the lead standard, he will be concluding that protecting public health and welfare requires lower concentrations of lead pollution in ambient air than the level previously held to be safe. Lead particles can be inhaled or ingested, and, once in the body, can cause lower IQ [intelligence quotient] and effects on learning, memory, and behavior in children. In adults, lead exposure is linked to increased blood pressure, cardiovascular disease, and decreased kidney function. […] The May 2008 proposal follows a multi-year review of the science. Assuming a new standard is promulgated, nonattainment areas will first be identified (not expected to occur until September 2011), following which there will be a 5-10 year-long implementation process in which states and local governments will identify and implement measures to reduce lead in the air. EPA has also proposed expanding the monitoring network for lead. Only about 3% of U.S. counties have lead monitors."
CRS Report for Congress, RL34479