Health & Environment Active Updated Jul 13, 2026

The Upper East Side Legionnaires' cluster

A Legionnaires' disease cluster emerged in Carnegie Hill and Yorkville on the Upper East Side in early July 2026, reaching 10 confirmed cases by Friday night. City health officials ordered testing of every cooling tower in ZIP codes 10028 and 10128 as investigators search for the source, against the backdrop of a 2025 Harlem outbreak that killed 7 people and hospitalized 90 after a hospital ignored its own maintenance plan.

The story so far

Jul 13, 2026 Latest

City health officials put the outbreak at 56 confirmed cases as of Saturday, with 16 hospitalized and no deaths. Owners of The Ardsley co-op at 320 Central Park West on the Upper West Side independently tested their hot water system and found Legionella, though health officials said the two situations are unconnected. The city had flagged 31 buildings, including the Guggenheim Museum and a Whole Foods, whose cooling towers preliminarily tested positive.

Health amNewYork
Jul 12, 2026

City Council Speaker Julie Menin said only 13.65% of registered NYC building owners have filed the Legionella tests required since the tightened cooling-tower law took effect May 8, calling the noncompliance inexcusable. Building owners who skip the required monthly tests face fines of $2,000 to $4,000.

Healthbeat
Jul 11, 2026

City health officials said the Guggenheim Museum is among 31 of 183 tested Upper East Side cooling towers that came back positive for Legionella, giving investigators their clearest signal yet of where the cluster lives. The Guggenheim and 18 other positive sites have already disinfected their towers, with the rest facing a Saturday deadline; the cluster has sickened 46 people and hospitalized 22 across three ZIP codes with no deaths reported.

Gothamist Hyperallergic
Jul 10, 2026

Mayor Mamdani said the city will publish the addresses of every Upper East Side building whose cooling tower tests positive for Legionella, calling it an unprecedented disclosure step. The cluster held at 36 confirmed cases and 22 hospitalizations, with 139 of 160 registered cooling towers tested and the source still unidentified.

6sqft Health amNewYork
Jul 9, 2026

The Upper East Side cluster reached 36 confirmed cases and 22 hospitalizations, with city officials having tested 139 of 160 cooling towers in the three affected ZIP codes without identifying the source building. Council Speaker Julie Menin sent a formal letter to Health Commissioner Dr. Alister Martin demanding an emergency order requiring every building owner in the area to proactively disinfect their cooling tower rather than wait for a positive test result; the health department said the request was under review.

Breaking NYC News & Local Headlines | New York Post
Jul 8, 2026

The Upper East Side cluster reached 23 confirmed cases and 17 hospitalizations, with city officials having tested 139 of 160 cooling towers in the three affected ZIP codes without identifying the source building. Mayor Mamdani pledged to publicly disclose any building that tests positive for Legionella.

Gothamist Gothamist
Jul 7, 2026

The cluster grew from 14 confirmed cases Sunday to 18 by Monday, with at least some patients hospitalized in critical condition. Health officials reported testing one-third of all cooling towers in the three affected ZIP codes without identifying the source building. The New York Post reported the number had since exceeded 20.

Politics | Spectrum News NY1 Breaking NYC News & Local Headlines | New York Post Gothamist Crain's New York
Jul 6, 2026

The cluster grew from 10 confirmed cases on Friday to 14 by Sunday, now spanning three ZIP codes: 10028, 10128, and 10075. NYC Health Commissioner Dr. Alister Martin said every cooling tower in all three ZIP codes was being tested but the contaminated source had not been identified as of Sunday. No deaths have been reported from this cluster.

Breaking NYC News & Local Headlines | New York Post
Jul 5, 2026

A Legionnaires' disease cluster grew from 2 confirmed cases Thursday to 10 by Friday night, all concentrated in Carnegie Hill and Yorkville. NYC Health Commissioner Dr. Alister Martin said every cooling tower in ZIP codes 10028 and 10128 is being tested; officials said tap water, showers, and air conditioners are safe, and that the bacteria spreads through mist from cooling towers, not between people. Anyone who visited the area since late June was advised to watch for fever, chills, cough, and muscle aches.

Gothamist

On the record

The checkable commitments in this fight, tracked until they are kept or broken.

Kept Jul 8, 2026 · resolved Jul 11, 2026

Publicly disclose the addresses of every Upper East Side building whose cooling tower tests positive for Legionella

Mayor Zohran Mamdani and the NYC Department of Health

“When there's a public health threat, New Yorkers deserve urgency and transparency from their government. That's why we're using every tool available to protect people by moving quickly to identify potential sources of exposure, requiring immediate remediation and making sure New Yorkers have the information they need to keep themselves and their families safe.”

On July 10 and 11, 2026 the city published the addresses of all cooling towers that tested positive for Legionella, 31 of 183 sites tested, including the Guggenheim Museum at 1071 Fifth Avenue. Health Commissioner Dr. Alister Martin said positive sites were ordered to disinfect, with 19 already remediated and the rest facing a Saturday deadline. Officials called it an unprecedented disclosure step.

Gothamist 6sqft Gothamist

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