Health commissioner attributes outbreak risk to climate change
The outbreak, centered in three Upper East Side zip codes, has prompted the city’s health department to take what Commissioner Martin described as an “aggressive” response. He said the city has signed orders for at least 19 buildings to drain, clean, and disinfect cooling towers, which are part of large buildings’ heating and cooling systems. Another official, who spoke on condition of anonymity, said those buildings are “buildings of interest” and that extensive testing would be needed to determine which may have been responsible for the outbreak.
“This is now a subtropical climate,” Martin said. “It is absolutely true that climate change is worsening our exposure and increasing the propensity for legionnaires’ disease clusters like we’re seeing today.”
Legionnaires’ disease is caused by the bacterium Legionella pneumophila, which is common in warm water environments. Most of the time, the bacteria are harmless, but when inhaled in vapors or mists, they can cause a spectrum of illness ranging from Pontiac fever to Legionnaires’ disease, a multi-system pneumonia that causes cough, fever, headaches, muscle aches, and shortness of breath. Although less than three people per 100,000 are infected each year, the disease kills as many as 10% of those diagnosed.
The bacteria were first identified in 1976 after a group of American Legion veterans fell ill in Philadelphia. Since then, outbreaks have been reported globally, including in New York, Melbourne, Italy’s Lombardy region, and Lincoln, New Hampshire. Urban conditions such as aging infrastructure, spotty maintenance, and populations with chronic conditions can spur outbreaks, experts said.
“You’re walking down the street minding your own business, breathing in the air, and the air may be contaminated from a cooling tower you can’t even see,” said George Yates, a 54-year-old Harlem resident who was diagnosed with Legionnaires’ disease during a 2018 outbreak in Washington Heights. Yates, who was driving for ride-share companies at the time, said he believed he contracted the bacteria while simply passing through the neighborhood. He was hospitalized for five days but recovered.
Dr. Benjamin Wyler, an emergency medicine physician at Mount Sinai Health System who has studied the disease, advised residents not to “live in fear of this” but said that anyone developing symptoms such as a febrile illness, cough, malaise, or gastrointestinal issues should “have a lower threshold to seek care.”
The current outbreak is geographically concentrated in a wealthy area, but multiple studies and past New York outbreaks have shown the disease disproportionately affects people living in poverty and Black Americans, a pattern that has frustrated local leaders.
“I started to believe that Legionella only knew Black and brown neighborhoods,” Marquis Harrison, chair of one of Manhattan’s community boards in Harlem, said at a public meeting in March. “We only saw it in the South Bronx and in Harlem, and only communities of color.”
The health department’s investigation is ongoing. Martin said New Yorkers will soon learn the names of buildings forced to clean their cooling towers, but the list will not identify the building at the center of the outbreak. Epidemiologists need to culture water samples to determine if the Legionella detected by PCR tests is a live colony, then sequence the genome and compare it to sputum samples from patients. However, doctors typically test for Legionnaires’ with a urine test, meaning some patients may not have sputum samples available. The health department said it could take another month before it can issue findings in the investigation, and in many smaller outbreaks, the CDC reports, the source is never found.
“Every summer we’re getting calls from people in New York who unfortunately are contracting this disease,” said Jory Lange, a Houston-based food safety attorney who represented 50 people sickened in a Harlem outbreak in 2025.
Even when the investigation is complete, experts said the effects of climate change will likely continue to make conditions favorable for Legionella. The bacteria have been found in a variety of reservoirs, including hot tubs, water jet cutters, floor scrubbers, and fountains. One study found truck drivers were particularly vulnerable to Legionnaires’ because of their use of “non-genuine windshield cleaner.”
“The bacteria don’t care,” said Dr. René Najera, director of public health at the College of Physicians of Philadelphia. “If they see a warm spot with water they’re going to thrive and multiply.” He added, “I don’t know if we’re past the point of no return on climate change, but certainly, it’s not helping.”