The new standard for lead in the air, 0.15 micrograms per cubic meter (microgram/m3), is a tenfold reduction from the current standard of 1.5 microgram/m3 and is within the range recommended to the EPA by its science advisors. The current standard dates back to 1978, a time when leaded gasoline was widely used in automobiles and children's average blood lead levels were seven times higher than today. Most importantly, in 1978, the serious effects of low level lead exposure on children were not yet well understood.
Lead is a potent neurotoxin that interferes with children's brain development and worsens performance on IQ tests. EPA's analysis has shown that to prevent a measurable decrease in IQ for the most vulnerable children in the country, the lead standard would need to be set as low as 0.02 microgram/m3. In addition to strong evidence for harm to children's neurological development at low levels, new science indicates that lead exposures throughout life can increase risks of cardiovascular illness and mortality.
Also in this final decision, EPA has chosen lead in Total Suspended Particulates (TSP) as the main indicator and the highest three month rolling average over three years as the form of the standard for monitoring and compliance. Because TSP captures more of the total available lead in the air than the alternative indicator under consideration, Particulate Matter less than 10 microns in diameter (PM10), it provides greater protection for a given level of the standard.
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