Normally, only a small fraction of the lead we are exposed to comes from breathing air that contains lead. Most lead humans are exposed to is ingested in food. However, because lead particles in air are so small, as much as 50 percent of the lead that is inhaled is retained in the body. Lead is a hazardous substance. Elevated levels above the national standard can adversely affect mental development and performance, kidney function, and blood chemistry.
Young children are particularly at risk due to increased sensitivity of young tissues and organs.
The primary sources of lead in Texas and the United States have been emissions from lead smelters and battery plants and from automobiles burning gasoline with lead additives. Transportation sources alone historically contributed about 80 percent of the annual emissions on a national basis. When it was determined that lead levels in the United States were too high and might contribute to health problems, environmental agencies took steps to eliminate some lead. For instance, now we use unleaded gasoline or alternative fuels in our automobiles. Gasoline with added lead can no longer be purchased as an automotive fuel in the United States.