NYC Health Department Provides Preliminary List of Upper East Side Cooling Towers Where Testing Confirms Live Legionella Bacteria
All 34 Cooling Towers with Live Bacteria Have Completed Remediation
A Fifth Person Has Died in Connection With the Legionnaires’ Disease Community Cluster
No New Cases Diagnosed in Six Days; No One Reporting New Symptoms in Over Ten Days
July 21, 2026 — The New York City Health Department announced today that confirmatory culture test results have come back positive for live Legionella bacteria in 34 cooling towers at 33 buildings on the Upper East Side as part of the investigation into a Legionnaires’ disease cluster in the area. Nine cooling towers have negative culture test results and culture test results for the remaining 140 cooling towers systems are expected over the next week. While culture testing is ongoing, all 34 cooling towers that tested positive for live Legionella bacteria have already undergone remediation and are fully cleaned, as are all buildings that previously tested positive for dead or live bacterial via PCR test. A list of addresses for cooling towers with a positive confirmatory test result will be updated daily on the NYC Health Department website. As of July 21, 82 cases of Legionnaires' disease have been identified. Five people have died.
“We have responded rapidly and aggressively to this to this Legionnaires’ cluster on the Upper East Side. With two confirmed cases, we launched our investigation and directed every building with an initial positive test result to immediately clean and disinfect its cooling tower. These actions have saved lives,” said NYC Health Commissioner Dr. Alister F. Martin. “We believe that through our aggressive strategy of testing and remediation we have eliminated the source of exposure. We will learn more as our investigation unfolds and look forward to updating our existing policies and procedures to preventing future clusters. Right now, we are focused on identifying the source of exposure through laboratory analyses and holding accountable anyone found out of compliance with local laws.”
A positive culture test confirms that a cooling tower has live Legionella pneumophila — the type of bacteria that can cause Legionnaires’ disease — prior to remediation. Again, at this time, all cooling towers that tested positive for live Legionella bacteria have already undergone remediation, are are all cooling towers that previously tested positive for live or dead bacteria via PCR test.
In addition, the Health Department has confirmed that a a fifth person has died in connection with the Legionnaires’ disease community cluster on the Upper East Side. As of July 21, the Health Department has identified 82 cases of Legionnaires’ disease associated with the cluster, eight people remain hospitalized, 56 have been discharged from the hospital, and five people have died. There have been no new cases diagnosed in 6 days, and no one reporting new symptoms in over 10 days. These figures may change as new cases are investigated and confirmed.
Taken together, these findings indicate that the City’s aggressive remediation and enforcement efforts have likely eliminated the source of the bacterial exposure. The Health Department continues to investigate newly reported cases and advise anyone who has spent time in the three affected ZIP codes — 10028, 10075, 10128 — to seek medical evaluation if they are sick with flu-like symptoms, as Legionnaires’ disease symptoms can appear up to 14 days after exposure.
The Health Department has conducted a full inspection of every cooling tower that tested positive for the presence of Legionella, as well as an unregistered cooling tower identified during the investigation. These inspections include a review of the cooling tower operating protocol and records of routine maintenance, and an assessment of the compliance with the law that owners conduct monthly Legionella sampling whenever the cooling tower is operating. Results from those inspections are being finalized. The Health Department will issue summonses subject to fines where inspectors identify non-compliance with City laws or regulations.
The Health Department’s Public Health Lab tests for Legionella bacteria using two different methods: polymerase chain reaction (PCR) screening tests, and confirmatory culture tests. PCR detects Legionella DNA but cannot distinguish between live and dead cells. The culture test involves incubating the samples over two weeks to see if live bacteria grow. Growth indicates the presence of live bacteria.
The vast majority of the 34 cooling towers with positive culture test results released today had a positive PCR test, all have been ordered to clean and disinfect, and all have completed the required remediation. Two cooling towers tested PCR-positive and culture-negative, confirming that any bacteria DNA detected through PCR was incapable of getting people sick. So far, there are seven cooling towers that have consistently tested negative on all tests. Four cooling towers were not PCR-positive, but were culture-positive. These four cooling towers have also been ordered to remediate. The Health Department conducts multiple forms of tests to ensure the most accurate and actionable results, while ordering buildings that receive a positive test result of any kind to clean and disinfect their cooling towers. In total, 82 cooling towers at 80 buildings have been ordered to clean and disinfect as part of the Health Department’s investigation, and all have completed remediation.
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MEDIA CONTACT: PressOffice@health.nyc.gov