The change, the first since 1978, would move the standard from 1.5 micrograms per cubic meter of air to 0.30 micrograms per cubic meter, the agency said.

A review of air quality standards was ordered by U.S. District Court in St. Louis in response to a lawsuit by the Missouri Coalition for the Environment in September 2005 over the levels of lead emitted by a lead smelter in Herculaneum, Mo.

Exposure to lead pollution is associated with damage to the central nervous system, cardiovascular system, kidneys, and red blood cells.

The Washington Post said environmentalists are critical of the proposal, saying that it doesn't go far enough. An independent scientific advisory panel and the EPA's scientific staff said the new standard should not exceed 0.20 micrograms of lead per cubic meter. EPA staff members said it could be set as low as 0.02 micrograms, the newspaper said.