Ken Pearl’s Apple Watch logs about 15,000 steps a day, mostly on the blocks around his Upper East Side apartment. The 63-year-old history professor estimates he regularly strolls on every street in the neighborhood.

“ What’s my thing I love? I walk everywhere,” he said.

That changed in July, when Pearl became one of 92 people diagnosed with Legionnaires’ disease in an outbreak that tore through the Upper East Side this summer and left him bedridden for weeks, unable to walk even 100 steps outside his front door.

”I felt like a boxer came and smacked me in the chest, there was remarkable pain,” he said.

It was the second outbreak in New York City in as many years, unusual compared to past outbreaks, with Harlem being last summer’s epicenter. More than 70 people were hospitalized in the most recent cluster between July and August, and earlier this month the outbreak passed a grim milestone when the death toll reached a total of nine people, surpassing last year’s fatalities.

Both outbreaks spurred city health officials into action to track down the source. Legionnaires’ disease spreads when cooling towers – part of a building’s air conditioning system – grow lethal levels of Legionella bacteria in hot summer months and cast it around a neighborhood via giant fans used to vaporize water.

More than 75 cooling towers on the Upper East Side tested positive for the bacteria in an initial round of testing, including at the Guggenheim Museum and the Metropolitan Museum of Art. The health department ordered building owners to drain their cooling towers and clean them to curb the disease’s spread.

But Pearl and other victims say the city has missed opportunities to protect New Yorkers. Public health experts agree that Legionnaires’ outbreaks are avoidable. They say that what’s clear, after two successive waves, is that the city has suffered from a lack of personnel to enforce existing regulations, and that it could benefit from the kind of stricter testing limits and hands-on approach that other cities have used to stop outbreaks from happening in the first place.

“Having a proactive, effective outbreak response is good,” said Chris Boyd, a water systems consultant who helped write the city’s cooling tower regulations in 2015. “Preventing the outbreak is better.”

Last year, the health department began increasing its number of inspectors after a Gothamist analysis found that the agency had only inspected about 24% of the city’s 4,900 cooling towers in the first six months of the year before the Harlem outbreak, a near-record low for the city. And in May, health officials said it would double its ranks of inspectors with new funding from the city’s budget.

But by the start of this year’s outbreak, the agency said that just 35 of 56 open positions had been filled and fully trained, And according to health department spokesperson William Fowler, it had inspected 1,580 towers in the first six months of 2026, only about 400 more compared to roughly the same period last year, before people started getting sick on the Upper East Side.

“Why did New York City not do more inspections?” Pearl said. “I blame New York City.”

Fowler did not respond to criticisms about the staffing delays but said the department responded aggressively once the outbreak began and eliminated the source quickly. He added that staffing levels now stand at 43 cooling tower inspectors, with six more currently being onboarded.

Fowler said there’s no way to prevent Legionella bacteria from growing in the built environment, but there are ways to reduce bacterial growth and prevent it from becoming a public health hazard. He said building owners must be vigilant and monitor their cooling tower systems daily.

“We always hold building owners accountable and have stepped up our enforcement this year, dramatically increasing inspections by 35% compared to the year prior,” he said, referring to the number of inspections conducted citywide in the first half of 2026.

He added that the agency collected $71,000 in fines since May.

A long recovery

Pearl’s tussle with Legionnaires’ began almost as soon as the outbreak started. He woke up feeling achy on July 3, a day after health officials announced the cluster of cases on the Upper East Side, and assumed he had the flu. But as his symptoms worsened over the next few days – chest pain, a fever of 104 degrees Fahrenheit – he decided to go to the emergency room.

Being a devoted walker, he stumbled his way to a clinic a few blocks away.

”You might say, ‘Why not take a cab?’ I hate cabs,” said Pearl, who has an endearing penchant for asking his own questions in an interview and answering them. “If someone saw me, they’d think, ‘Oh my God, what’d this guy drink?’”

Nisian Hughes/Getty Images

Legionnaires’ disease is a severe type of pneumonia that causes a litany of flu-like symptoms: fever, body aches, extreme fatigue and diarrhea. Elderly patients and immunocompromised people are at a much higher risk of developing severe cases.

After a battery of tests, he said he was prescribed a nine day course of antibiotics, but that his recovery was slow. He spent the rest of the month horizontal, barely able to lift his head high enough to watch World Cup matches on television.

”There were times where I was like, ‘I know I have to brush my teeth. I can’t get out of bed,’” Pearl said.

Near the start of August, he said he finally ventured outside again for a short trip to Target to buy a new garbage can with his wife. “Target’s two blocks away. It was an achievement at that point to walk the two blocks,” he said.

By that time, city officials had declared the outbreak over after conducting a blitz of cooling tower inspections in the affected ZIP codes and issuing over 100 violations. Dr. Alister Martin, the city’s health commissioner, said his agency had identified two building owners in the area that it considered particularly “bad actors,” including one who had not registered their cooling tower with the city as required by law.

Cooling towers typically sit on roofs and are the last stop for water that has been circulated through a building as part of its cooling system. These large metal boxes contain fans that transform that water into vapor and blow it into the air.

If not properly maintained, cooling towers can become giant Petri dishes for Legionella bacteria that can wind up in the lungs of passersby.

New York City has some of the toughest cooling tower regulations in the country, according to the city’s health department and many water management experts. Building owners have to develop and follow detailed maintenance plans and regularly test for Legionella to keep outbreaks at bay.

“The global public health consensus is that these are preventable,” Boyd said.

And when Legionnaires cases spike, epidemiologists say human negligence is typically to blame.

The health department aims to inspect every cooling tower at least once a year to ensure owners are complying with the rules. But a review of inspection data shows the agency has struggled to meet that goal.

Among the cooling towers located in the three affected ZIP codes on the Upper East Side, about half had either not been inspected in the past year before the outbreak began, and about 26% of building owners failed to report required Legionella tests in the first half of the year, about 4 percentage points higher than the citywide rate.

Lack of inspectors

This summer had the prospect of being different.

Health department officials had blamed the record low level of inspections before last year’s Legionnaires outbreak in Harlem on a lack of staffing under then-Mayor Eric Adams and vowed to increase its ranks. The disease killed seven people in a two-month span between July and August in 2025.

Patricia Miller, a 72-year-old Harlem resident who got sick last year, said she lives across the street from the source of the outbreak and was out of work for two months. The emotional trauma lasted even longer. Nearly a year after the outbreak, she said she still avoided walking outside or taking the subway.

“This thing that happened to me had made me become so afraid,” she told Gothamist in March. “I call a cab to take me to work.”

Harlem Hospital

Anne Czichos/Getty Images

A 2015 outbreak in the Bronx was even worse. Seventeen people died, prompting city lawmakers to install strict cooling tower regulations. The first year the rules were in place, 2017, the health department inspected 3,200 cooling towers, nearly all of those registered with the city at the time, but it has never reached those levels since.

In the immediate aftermath of the Harlem outbreak, health officials announced that the agency had hired 6 more cooling tower inspectors, raising the total number to 30. And in May, the department received an additional $13 million in the 2027 budget, part of which would go to adding 23 additional cooling tower inspectors to its payroll.

But in July, the health department told Gothamist it had just 35 inspectors in place at the start of the outbreak on the Upper East Side. By then, about 45% of cooling towers registered with the city had still not been inspected in the year since officials said they would ramp up their efforts.

In other words, inspections had increased, but the city was nowhere close to meeting its goal.

Jeffrey Siegel, an engineering professor at the University of Toronto who specializes in building ventilation systems, said preventing outbreaks comes down to money. He said building owners need to invest in hiring reputable companies to manage their water systems, and city governments need to invest in hiring enough staff to enforce health regulations.

“It’s usually a question of how many resources should be put towards it versus towards other priorities,” he said, adding that the vast majority of people follow the rules. It’s when they don’t that problems arise.

Karen Small, 66, said she had no idea Legionella could spread in the city until last year’s Harlem outbreak.

“I always thought it was something you get on cruise ships,” Small said. “I just never thought that it would be in my area.”

She was diagnosed in early July and believes she may have been infected while out walking her Maltipoo, Travis, near her Upper East Side apartment. She also blames both the city and the building owners in her vicinity for failing to prevent the spread of the deadly bacteria.

“When something could be preventable, that’s what makes it very disturbing,” she said. “They knew these systems should have been cleaned regularly.”

Complex systems

When the 2025 outbreak in Harlem ended last August, the city health department matched the genetic material of bacterial samples collected from patients to Legionella bacteria found in two cooling towers.

The first was located at a construction site for a public health lab owned by the city. A construction company called Skanska was managing the site. The second was located at Harlem Hospital, adjacent to the construction site.

More than 50 victims filed a series of lawsuits against the city health department, Skanska and other subcontractors earlier this month accusing them of negligence.

A spokesperson for Skanska declined to comment due to pending litigation.

Karen Small believes she contracted Legionnaires while walking her dog near her Upper East Side apartment.

Joe Hong

Mitchell Katz, CEO and president of NYC Health and Hospitals, the agency that operates Harlem Hospital, said hospital staff had “exceeded the requirements” for managing its cooling towers.

City regulations require building owners to design specific maintenance plans for their cooling towers, submit them to the city and follow them closely. But a Gothamist investigation earlier this year found that Harlem Hospital had failed to follow its own maintenance protocols for conducting rapid testing of its cooling towers for Legionella in the months leading up to the outbreak.

In response, a spokesperson for NYC Health and Hospitals said the rapid testing went beyond what is required by the city’s health code and was therefore not required. The health department agreed and declined to issue a violation to the hospital.

Boyd and other experts expressed alarm that the hospital had failed to follow its own protocols, regardless of whether they exceeded the minimum requirements laid out in city law.

Boyd said each cooling tower has its own unique needs that are dependent on a variety of factors like the elevation of the roof or wind direction, and requires a highly specific management plan.

“These are complex systems with lots of moving parts,” Boyd said.

He also recommended that the health department modify its reporting requirements for Legionella testing. Building owners are currently only mandated to report the dates they conducted tests. They only have to report results if they show 1,000 or more colony-forming units of Legionella bacteria per milliliter.

Boyd said that threshold is far too high. He pointed to Vancouver, which requires remediation at only 10 colony-forming units per millimeter.

He said lowering the threshold allows for earlier detection and enables a city inspector to take a more collaborative approach with a building owner. The current regulation in New York City, Boyd said, relies too much on fining building owners rather than on working with them to find better ways of managing cooling towers.

He said in Vancouver, a small spike in bacteria results in a visit from the city inspector, who consults with the owner to adjust disinfectant levels or cleaning schedules. Boyd said this approach has led to dramatic decreases in positive Legionella tests.

“Inspectors provide more technical direction on what to improve,” he said. “The New York City Council should be focused on adopting that strategy.”