Legionnaires’ Disease Outbreak Hits New York, Officials Rush to Disinfect Cooling Towers

New York City health officials are racing to disinfect cooling towers across Manhattan’s Upper East Side after a Legionnaires’ disease outbreak sickened 46 people, sending 22 patients to hospitals and prompting an aggressive effort to contain the bacteria before more residents become ill.

City officials said Friday that testing has been completed on all cooling towers in the affected area after investigators linked the outbreak to Legionella bacteria found in multiple building cooling systems.

According to New York City Health Commissioner Dr. Alister Martin, the bacteria have been detected in 31 cooling towers, with 19 already disinfected and the remaining towers expected to be cleaned by Saturday.

The outbreak has heightened concerns among residents while reigniting questions about how cities monitor cooling towers, which can spread Legionella bacteria through water mist. Health experts stress that the disease is not spread from person to person, but through inhaling contaminated water droplets released from infected cooling systems.

City Moves Quickly to Contain the Outbreak

Mayor Zohran Mamdani said the city had completed testing of all cooling towers in the investigation zone as officials accelerated efforts to stop additional exposure.

The Health Department has also changed its response strategy by requiring buildings to fully clean and disinfect cooling towers immediately after a single positive test, rather than waiting for additional confirmation.

Speaking at a community town hall this week, Martin said early detection had helped officials move quickly.

“What we have in front of us is 160 cooling towers across this region that we are looking at, and we are not waiting,” Martin said, according to ABC News.

Officials believe rapid testing and mandatory disinfection will reduce the amount of Legionella bacteria released into the air.

What Is Legionnaires’ Disease?

Legionnaires’ disease is a severe form of pneumonia caused by Legionella bacteria, which naturally grow in warm water and can multiply inside poorly maintained cooling towers, plumbing systems, decorative fountains, and other water systems.

People become infected after inhaling tiny droplets of contaminated water suspended in the air.

Unlike respiratory viruses such as COVID-19 or influenza, Legionnaires’ disease does not spread between people.

Symptoms often resemble pneumonia and include fever, cough, chills, muscle aches, headaches, and shortness of breath. Older adults, smokers, and people with weakened immune systems face the highest risk of severe illness.

According to city officials, 22 of the 46 infected patients required hospitalization, with several receiving treatment in intensive care units.

Residents Seek More Guidance

The outbreak has unsettled many Upper East Side residents, who packed a community meeting seeking answers from city health officials.

Resident Justine Kirby said she has been wearing an N95 mask outdoors and keeping her apartment windows closed while waiting for contaminated towers to be disinfected.

“There is quite a level of concern in the community,” Kirby said.

She added that although officials have emphasized the overall public risk remains low, residents wanted clearer advice about additional precautions.

“They could quite reasonably say, ‘Because risk is low, we’re not recommending everyone mask outside. However, a good, well-fitted mask will protect you.’ I think they could’ve gotten into that.”

The city’s Health Department has advised residents to monitor for symptoms and seek medical care if they develop signs consistent with Legionnaires’ disease.

Experts Explain How the Bacteria Spreads

Dr. Wafaa El-Sadr, professor of epidemiology at Columbia University’s Mailman School of Public Health, said the outbreak is linked to cooling towers used in large commercial buildings.

“The current outbreak is caused by cooling towers from larger buildings where Legionella bacteria live and multiply, infecting people when they breathe in the bacteria from the mist of the towers,” she said.

El-Sadr added that wearing a mask and keeping windows closed may reduce exposure for people living within the immediate outbreak area, although health authorities have not issued a citywide masking recommendation.

She also noted that warmer temperatures associated with climate change could contribute to more frequent Legionnaires’ outbreaks because the bacteria thrive in warm water environments.

Questions Raised Over the City’s Response

While city officials say they acted quickly after identifying the outbreak, some local leaders argue that stronger action should have been taken sooner.

New York City Council Speaker Julie Menin criticized the city’s response in a letter to Health Commissioner Martin, saying she was “deeply concerned” that officials had not required all cooling towers in the investigation zone to be proactively disinfected, rather than waiting for positive test results.

The Upper East Side contains more than three times as many cooling towers as were inspected during last year’s Legionnaires’ outbreak in Harlem, where 114 people became ill, and seven died after contaminated cooling towers were identified as the source.

Officials say continued testing, mandatory disinfection, and public awareness remain the best tools for preventing additional infections as they work to bring the current outbreak under control.