WASHINGTON - THE Environmental Protection Agency has announced the tightest air quality standards for lead in 30 years, but warned it will take four years to enforce them as the existing monitoring network for the element is updated.

The new limit has been tightened to 0.15 microgrammes of lead per cubic metre of air, a level 10 times smaller than the 1.5 microgram standard set in 1978.

It is also 0.2 microgrammes lower than EPA scientists had recommended, the agency said in a statement.

'America's air is cleaner than a generation ago,' EPA Administrator Stephen Johnson said on Thursday. 'With these stronger standards a new generation of Americans are being protected from harmful lead emissions.'

Lead emissions have fallen by 97 per cent in the United States since 1980, due largely to the gradual elimination of leaded gasoline for vehicles.

The EPA said its existing monitoring network for lead is insufficient to determine whether many areas of the country would meet the revised standards.

There are plans to boost the current 133 control stations around the country to more than 300, said EPA spokesman Cathy Milbourn, adding that by October 2011 the agency will designate areas that must take additional steps to reduce lead air emissions.

States will then have five years to meet these new standards after designations take effect, the EPA said. -- AFP