Criteria Pollutants

Criteria Pollutants: Definitions & Health Effects

  1. Lead
  2. Sulfur Dioxide
  3. Carbon Monoxide
  4. Nitrogen Oxides
  5. Ozone
  6. Particulate Matter

Lead (Pb)

Lead is a naturally occurring element found in the earth's crust. While it has some beneficial uses, it can be toxic to humans and animals. With Environmental Protection Agency (EPA) regulatory efforts, including the removal of lead from motor vehicle gasoline, levels of lead in the air decreased by 98% between 1980 and 2014. The remaining sources of lead emissions vary from one area to another. At the national level, major sources of lead in the air are ore and metals processing and piston-engine aircraft operating on leaded aviation fuel. Other sources are waste incinerators, utilities, and lead-acid battery manufacturers. The highest air concentrations of lead are usually found near lead smelters. Lead is also persistent in the environment and can be added to soils and sediments through deposition from sources of lead air pollution.

Elevated lead in the environment can result in decreased growth and reproductive rates in plants and animals, and neurological effects in vertebrates. Lead distributes throughout the body in the blood and is accumulated in the bones. For humans, lead can adversely affect the:

  • Cardiovascular system
  • Developmental system
  • Immune system
  • Kidney function
  • Nervous system
  • Reproductive system

Lead exposure also affects the oxygen carrying capacity of the blood. The lead effects most commonly encountered in current populations are neurological effects in children and cardiovascular effects (e.g., high blood pressure and heart disease) in adults. Infants and young children are especially sensitive to even low levels of lead, which may contribute to behavioral problems, learning deficits and lowered IQ.