In the last four months, his agency, H.U.D. and the Centers for Disease Control have submitted reports to Congress on lead-paint hazards.

Landlords will not be held culpable if they can persuade a fact-finder that "diligent and reasonable" efforts were made to eliminate a lead-paint hazard, he said.

The law, which regulates the removal of lead-paint hazards, including dust, from apartments built before 1960, goes into effect in August.

Mr. Miller replied that he wanted smaller class sizes and higher pay for teachers, and had already shown that he could pass tough laws to address lead-paint hazards and other problems.

When a hazard is found, inspectors from the city's Housing Preservation and Development Department issue a violation, she said, and, if necessary, send contractors to remove the lead-paint hazard, billing the landlord.

The new law regulates the removal of lead-paint hazards, including dust, from apartments built before 1960.

City officials say the law is too broad and too costly because court opinions have interpreted it as requiring the encapsulation or removal of all lead-paint hazards in apartments with children.

Mayor Michael R. Bloomberg yesterday vetoed a City Council measure that would regulate the removal of lead-paint hazards, including lead dust, from older apartments where young children live.

In another controversial case, the State Court of Appeals struck down a New York City law that governs how property owners must address lead-paint hazards in residential buildings.

He vowed that they would override the mayor's veto of their legislation that would govern the removal of lead-paint hazards in older apartments where young children are living.