The city has decontaminated five cooling towers in the south Bronx that could be the culprits of the worst breakout of Legionnaires' disease in New York City history. 

Since July 10, there have been seven deaths and 86 cases of Legionnaires Disease in the South Bronx, according to the health department. Legionnaires’ is a type of pneumonia caused by the bacteria legionella that grows in warm water. 

Speaking at Lincoln Hospital, Mayor Bill de Blasio on Tuesday pledged to introduce legislation later this week for stricter standards for cooling tower to “minimize this ever happening again.”

“We are going to be very aggressive dealing with this problem,” de Blasio said, adding the bacteria has been found in newer cooling towers on buildings, which are not monitored by the building department. 

Legionnaries’ is treatable with antibiotics, said Health Commissioner Dr. Mary Bassett, but can prove fatal for the elderly and those with with pre-existing health conditions. Bassett said anyone with symptoms — fever, cough, chills, sore muscle and headaches — should seek immediate medical attention. 

Bassett said cases should start to decline next week as the maximum incubation period is 10 days, and the outbreak peaked on July 30.  

"This is the largest outbreak that we are aware of in New York City," Bassett said. Last year, there were eight cases of Legionnaires' in Co-op City in the Bronx. 

Bassett said more testing will determine why the outbreak was in the South Bronx. 

The death toll rose from four to seven on Monday. About 250 people attended a town hall meeting with teh health department on Monday night in the Bronx to have their questions answered and concerns heard.