The most common sources of lead emissions are gasoline additives, non-ferrous smelting plants, and battery manufacturing. Historically, lead was added to gasoline as an additive to prevent engine knocking. The lead content of gasoline began to be controlled in the 1970s when legislation was introduced to gradually reduce lead levels. Currently, smelters and battery plants are the major sources of lead nationwide. Human exposure to lead can occur through ingestion or inhalation. The nervous system is most sensitive to the effects of lead and high exposures to lead can result in behavioral and learning disorders. Lead also may be a factor in high blood pressure and heart disease. 

Concentrations of lead in the air decreased steadily in the 1980s after the removal of lead from gasoline. On October 15, 2008, EPA revised the national ambient air quality Standards (NAAQS) from 1.5 micorgrams per cubic meter (µg/m3)
 to 0.15 µg/m3.  Michigan has recommended areas for designations (see below) and is currently waiting for more information from EPA.

Michigan Proposed Lead Infrastructure SIP Open for 30 Day Public Comment (January 2012)

Other Resources:  

• EPA Letter to Michigan's Governor (11-11)
• Final Designation for 2008 Lead NAAQS (11-11)
• Belding Technical Support Document for 2008 NAAQS Designations (11-11)
• EPA Recommendations for Lead Designation (June 2011)
  Lead Attainment Map 
• Lead Monitoring Network 

Recommended EPA Resources: 

• Federal Revisions to National Air Quality Standards for Lead  EPA has substantially strengthened the national ambient air quality standards for lead.
• Lead - How Lead Affects the Way We Live and Breathe- Today, metal processing plants are generally responsible for most of the lead in the air. 
• Lead in the Environment- Testing children for lead poisoning, sources of lead, health effects, techniques for reducing exposure at home. English / Spanish. 
• Lead in Paint, Dust, and Soil- These pages are designed to give you access to information on all aspects of the Federal lead poisoning prevention program. 
• Protect Your Family From Lead in Your Home- These publications provide information on detecting possible lead hazards in the home, what to do if hazards are found to exist, the effects of lead in the body, and advice on how to significantly reduce lead hazards.