Manhattan District Attorney Cy Vance announced Tuesday that his office would no longer prosecute any low-level marijuana offenses, including smoking in public.

It is planned to take effect August 1.

According to one analysis by the DA's office, the policy is expected to reduce marijuana prosecutions by 96 percent. That could reduce marijuana prosecutions from about 5,000 a year in Manhattan to just 200.

Meanwhile, Mayor Bill de Blasio promised changes to the way police handle marijuana arrests. Speaking in Washington on Tuesday, the mayor promised the NYPD would reform and overhaul marijuana arrest policies.

Following the mayor's announcement, the NYPD said it would consult experts, advocates, and other outside groups during a 30-day policy review.

Acknowledging racial disparities, Police Commissioner James O'Neill said, "We need an honest assessment about why they exist....The NYPD has no interest in arresting New Yorkers for marijuana offenses when those arrests have no impact on public safety."

De Blasio's announcement came after City Council Speaker Corey Johnson called for change to address the disparity in arrest numbers between white people, and black and Latino people.

To address the disparity, city leaders are calling for full marijuana legalization on a state level. They are also calling on the NYPD to no longer arrest people caught smoking marijuana in public, and issue a summons instead.

"It's going to be smoked in public. So when it's smoked in public, how do you handle it? We don't believe that jailing young black and Latino men at a substantially higher rate makes any sense," Johnson said.

The city comptroller released a report on potential tax earnings from legalizing marijuana that found that marijuana could be a $3.1 billion industry statewide, with the city collecting $336 million in tax revenue, and the state getting $436 million.

On the state level, Gov. Andrew Cuomo commissioned a study on legalization earlier this year. Its findings are expected any day.

Meanwhile, the New York Democratic Party is expected to endorse legalization at its convention next week.