New York City Health Commissioner Dr. Michelle Morse said Friday she supports a proposal to require building owners to test their water-cooling towers more frequently for Legionella, along with other reforms she said could help reduce the risk of future outbreaks.

But she added there are no foolproof guarantees, despite disease experts saying that Legionnaires’ disease is largely preventable with proper water-system maintenance.

“We are fighting nature in many ways and it’s very difficult to get the risk [of Legionnaires’ disease] to be zero,” Morse said during a City Council oversight hearing on this summer’s Legionnaires’ outbreak in Central Harlem. More than 100 people were sickened in the outbreak, 90 were hospitalized and seven died.

She defended the health department’s response to the outbreak — the deadliest since 2015, when 16 died in a cluster in the South Bronx — while councilmembers pressed the commissioner on decisions around the department’s communications with the public during the crisis and a decline in city inspections of cooling towers in recent years.

But Morse said the health department’s ability to identify an emerging cluster of cases in Harlem in late July and quickly inspect and treat local cooling towers for Legionella led the outbreak to be less severe than it could have been — adding that “any loss of life is too much.”

The outbreak is expected to spur scores of personal-injury lawsuits filed by people who were sickened or lost loved ones.

Councilmembers said many Harlem residents didn’t feel adequately informed about the outbreak. Morse outlined the city’s communications across multiple platforms, including social media, radio and ads that ran on LinkNYC towers in Harlem. She said the city is planning to hire more community health workers who can help communicate with New Yorkers on the ground about any future health issues, including Legionnaires’.

The health commissioner endorsed a bill introduced by Council Health Committee Chair Lynn Schulman, which would require buildings to test cooling towers for Legionella every 30 days, rather than every 90 days, as is currently required, and even more frequently during heat waves. Morse called the proposal “an experiment” that may or may not be effective.

Legionella can grow in water-cooling towers, which are part of some buildings’ cooling systems. If the bacteria is in the mist emitted by the cooling towers, it can cause people in the surrounding area to contract Legionnaires’, a type of pneumonia.

Some experts have told Gothamist that the protocols for how cooling towers are tested matters as much as testing frequency, noting that if they are tested for Legionella right after being treated, the results can be misleading.

Corinne Schiff, the deputy commissioner of environmental health at the city health department, said the city is working to hire additional water ecologists to inspect cooling towers, since the city says a staffing shortage has led to fewer inspections in recent years.

However, Schiff rejected Council Speaker Adrienne Adams’ suggestion that more frequent inspections of Harlem cooling towers could have prevented the outbreak.

“Even had we been fully staffed here, we do think this risk was still present and those inspections would not have been able to prevent what happened here,” Schiff said.

Morse called each inspection nothing more than a “snapshot” of how well a tower is maintained. But the results of city inspections posted online show that inspectors also review buildings’ records and maintenance plans, not just what the tower looks like on the day of the visit.

The city’s investigation into the Central Harlem outbreak found 12 cooling towers in the area that tested positive for Legionella, including several city-owned buildings, and ultimately tied the outbreak to two of them. One of those cooling towers was at Harlem Hospital, part of the city-run NYC Health and Hospitals network.

City officials said at the hearing that Harlem Hospital was found to be compliant with the laws around cooling tower maintenance.

Morse and Schiff said the city is still working to figure out why the other cooling tower responsible for the outbreak was not registered with the city, as required by law. That tower is located at a construction site for a building owned by the city’s Economic Development Corp., which is overseen by the construction company Skanska.

Morse was not supportive of all the reforms that have been proposed in the wake of the outbreak. She rejected legislation seeking to put in place broad new maintenance requirements for buildings’ plumbing systems, which can also house Legionella bacteria, arguing that outbreaks are typically linked to cooling towers.

The city health department has previously said the source of most of the hundreds of Legionnaires’ cases reported in the city each year is unknown. Several building clusters are identified each year, according to a surveillance report on Legionnaires' from 2019 to 2022.