The Biden administration on Wednesday proposed new federal rules to reduce the level of harmful lead dust in millions of homes, schools and child-care facilities.

Even though lead has been phased out of paints for decades, the harmful substance is still found in many older buildings. The Environmental Protection Agency estimates lead paint is still in about 31 million houses built before 1978, and 3.8 million of those homes house one or more children under the age of 6.

The EPA is proposing to revise federal standards to find any level of lead dust to be hazardous and requiring owners to pay for abatement. The current standard defines hazardous lead dust levels as 10 micrograms per square foot for floors and 100 micrograms per square foot for window sills.

If enacted, the new rules would compel building owners to clean up toxic lead dust, lowering lead exposure for approximately 250,000 to 500,00 children under 6 each year.

The federal government banned the use of lead-based paint in homes and residential buildings in 1978 due to its adverse health impacts on children -- particularly babies and toddlers. Lead exposure in young children can lead to brain and organ damage, as well as learning disabilities.

The youngest children are particularly vulnerable because they crawl on floors and hang onto windowsills that could be contaminated with lead-based paint dust, leading to high exposure when they put their hands in their mouths.

"There is no safe level of lead," Michal Freedhoff, the assistant administrator for the EPA's Office of Chemical Safety and Pollution Prevention, said in a statement. "Even low levels are detrimental to children's health, and this proposal would bring us closer to eradicating lead-based paint hazards from homes and childcare facilities across the US once and for all."

The stronger proposal follows a 2021 decision by a federal appeals court after the EPA was sued by public health and environmental groups over its old standard.

Biden administration officials reiterated that this proposed rule was part of their larger agenda to get lead out of the nation's housing and school stock.

"This proposal to safely remove lead paint along with our other efforts to deliver clean drinking water and replace lead pipes will go a long way toward protecting the health of our next generation of leaders," EPA Deputy Administrator Janet McCabe said in a statement.

The EPA will take public comment on the new rules for 60 days.