NYC Health Officials Report Legionella Findings in Cooling Towers of 76 Buildings

New York City health officials have identified Legionella bacteria in the cooling towers of 76 buildings, including the Guggenheim Museum, the Metropolitan Museum of Art and a pre-war co-op on the Upper West Side. As of Tuesday, 63 people have been hospitalized for Legionnaires’ disease, and 40 have been discharged; no fatalities have been reported.

Epidemiologist Dr. Wafaa El-Sadr of Columbia University’s Mailman School of Public Health explained that the bacteria spread through aerosolized mist from cooling towers, not through tap water, showers or cooking water. "It is spread by actually breathing in this mist; it is not passed from person to person," she said.

Most exposed individuals do not develop symptoms, but older adults, smokers and people with chronic lung, kidney or heart conditions are at higher risk. Dr. El-Sadr recommended that those in higher-risk groups consider wearing a mask when near affected towers, while the general public need not avoid walking in the area.

When a tower tests positive, the city requires the water to be drained, dried and treated, followed by ongoing monitoring. The health department also conducts rapid and more detailed laboratory tests to link environmental samples with patient isolates.

The recent detection at the Ardsley building on the Upper West Side appears unrelated to the Upper East Side cluster, suggesting separate sources rather than city-wide spread. Dr. El-Sadr noted increased transparency from building managers, who are now more likely to disclose positive tests and initiate mitigation promptly.

City officials continue to enforce regular testing schedules and public-health messaging to keep residents informed about Legionella risks and prevention measures.