Mayor Bill de Blasio is back from vacation and facing a flurry of questions about the city's failure to conduct mandatory lead paint inspections of public housing apartments. He admitted Monday to having regrets about how he handled the issue, but he is standing by the head of the housing authority and said she should stay. NY1 Political Reporter Grace Rauh filed the following report.

"In retrospect, I wish we had," de Blasio said Monday.

New Yorkers may just be learning that the city failed to inspect public housing apartments for lead paint, but Mayor de Blasio has known for a year-and-a-half — he just hasn't said anything.

"In retrospect, it would have been better to say, 'Hey, we also need to go back and correct that record,'" de Blasio said at a press conference Monday. "But actions speak louder than words."

The actions that the mayor referred to are the toxic lead paint inspections, which quietly started up again shortly after City Hall was notified that they had lapsed.

Since de Blasio took office, four children in public housing apartments were found to have elevated lead levels — two from paint. Officials say none have shown any sign of medical problems.

"Thank God, no lasting health impact that we can find at this point," de Blasio said.

The mayor is also defending Shola Olatoye, the chair of the public housing authority. "She is absolutely part of the solution," de Blasio said.

He said officials at the agency have been held accountable. Two housing executives resigned, and another was demoted on Friday.

The mayor was asked why that happened only after the city's Department of Investigation drew attention to the problem.

"When it was time to take those personnel actions, we took them," de Blasio said.

As for talk that de Blasio wants to fire Mark Peters — the Department of Investigation commissioner who issued a report on the lead paint last week — the mayor would only say this:

"I'm not going to speak about any personnel matters," de Blasio said.

The mayor fielded the questions in his first news conference since returning to the city from his Connecticut vacation. He announced Monday that he would be packing his bags again soon.

He is traveling to Iowa next month to deliver a speech. Iowa is home to the first presidential nominating contest.

"I just don't buy the notion in the 21st Century that if you leave the boundaries of the five boroughs, the government ceases to work," de Blasio said.

As for talk that the mayor might be eyeing a presidential run in 2020, he said he is going to serve out his second term, which ends in 2021.