TRENTON -- In an about-face, Gov. Chris Christie announced Tuesday the state will commit $10 million to this year detect and remove lead paint from as many as 500 old homes and apartments that threaten to poison thousands of children in New Jersey.

The Republican governor's decision comes after longstanding pleas from public health officials and affordable housing advocates that he stop diverting some $7 million to $10 million a year from a lead abatement fund supported by a 50-cent tax on paint.

Christie has vetoed legislation three times that would have allocated $10 million for lead abatement activities, and has criticized legislators for not included the funds in the budgets that have approved. A month ago, he called the concern about lead poisoning in old housing "an overdramatized issue" because testing and abatement work has contained the problem.

But on Tuesday, Christie said he had changed his mind.

"It's been proven to me by my staff that (spending more is) necessary," Christie told reporters at a Statehouse press conference.

Christie said he wanted to address the complaints that the state isn't spending the $10 million it is supposed to spend on lead remediation. Once he determined that was happening, his next question was, "Do we need to do more to get a handle on this issue?" he said.

His staff said another $10 million would be helpful, Christie said.

Christie said he found the money in the current budget and earmarked it for the assessment and remediation of one- and two-family homes and apartments at $20,000 a piece. The Department of Community Affairs will coordinate the effort.

Christie stressed the state has made great progress in combatting the problem. Last year, 205,600 children were tested for lead exposure, compared to 10,200 in 1998.

"New Jersey has been a national leader on the issue of lead paint in housing and the resulting decline in cases proves that point, so we are working hard and making sure that lead poisoning -- while it is a concern -- does never become an epidemic in New Jersey," the governor said.

Staci Berger, advocacy director of the Housing and Community Development Network of New Jersey, called the governor's actions "a huge victory."

"There are more than 109 organizations that have asked him to do this," Berger added. "I am glad he has listened to those organizations and the parents that have come forward."

Emphasizing the testing of homes will mean the difference between preventing lead poisoning and treating it, she said.

New Jersey has one of the oldest housing stocks in the country, with most homes built before 1978, the year lead paint was outlawed. There is no safe level of lead exposure in children, according to the U.S. Centers for Disease Control and Prevention. Lead poisoned children may experience learning delays, vision and hearing impairments, and extreme cases, death.

Lead testing is required by state law for children at ages 1 and 2 and by age 6 if the earlier milestone have been missed. Health advocates say compliance has been weak, with most children only getting tested once.

David Henry, health officer for the N.J Association of County and City Health Officials called the governor's announcement "great progress."

Henry also asked whether Christie would support pending legislation that would require New Jersey to follow the stricter guidelines the CDC recommended in 2012, when it cut in half the amount of lead exposure that warrants intervention.

The CDC recommends follow-up if a child's blood test reveals at 5 micrograms per deciliter of lead in the blood. New Jersey relies on an old recommendation that calls for monitoring at 10 micrograms.

The difference is between reaching nearly 900 children whose lead levels exceeded 10 micrograms last year, and 3,500 children whose readings were between 5 and 9 micrograms, Henry said.

Jeff Tittel, director of the New Jersey Sierra Club and a frequent critic of the governor, called Christie's announcement "misleading."

"The $10 million that he said he's giving for lead abatement for paint in homes should have been in the budget in the first place," Tittel said.

Adam Clark may be reached at adam_clark@njadvancemedia.com. Follow him on twitter at @realAdamClark. Find NJ.com on Facebook.