New limit dust limit on floors is 10 µg/ft2
Old limit lead dust limit on floors is 40 µg/ft2
New limit dust limit on window sills is 100 µg/ft2
Old limit lead dust limit on window sills is 250 µg/ft2
These lead levels are scheduled to become law on January 6, 2020 in California.
These new lead dust limits are from EPA. However, HUD also regulates acceptable levels of lead dust in HUD properties. So, you need a professional that knows what standard is used for what type of property. For example, if a home is going to be re-occupied as housing managed by a Department of Housing and Urban Development grantee, it would need to meet the HUD clearance standard with levels lower than the EPA clearance levels.
So, it will depend on who will occupy the building what Standards your project will require.
These new EPA lead dust limits apply to homes built before 1978 and to childcare centers. These new limits go into effect 180 days after publication in the Federal Register.
You can get the pre-publication of the EPA Rule here.
The old rules had been in place since 2001. This level reflected the CDC’s level of concern for lead in children’s blood as 10 µg/dL. More current CDC guidance of the level of concern for lead is 5 µg/dL. So, the level is much less now.
There is a history of litigation regarding lead-based paint and acceptable levels of lead dust. Read What Happened to the $1.15B Lead Paint Lawsuit in Santa Clara?
The EPA was sued to update the allowed lead levels. However, in December 2017 order by a federal appeals court that required EPA to issue new lead standards within 90 days, a deadline that was later extended. At the time of the court’s ruling, the agency had been working on the standards for about six years and had said it would need six more years to complete them, according to NPR.