Inspections Lapsed Before Deadly Legionnaires' Outbreak, Data Shows

HARLEM, NY — The city's inspections for Legionella bacteria in cooling towers dropped in the months leading up to the ongoing outbreak of Legionnaires' disease, that has sickened 83 people, killing three in the past two weeks, according to city data.

Legionnaires’ disease, a type of pneumonia, is caused by bacteria called Legionella that thrives in warm water environments, like cooling towers, which create cold air by cycling warm air through water, creating a warm, humid environment within the system. The disease spreads by inhaling contaminated vapor, but is not contagious from person-to-person, officials said.

City data first reported by Gothamist shows that in the first three months of 2025, just 800 of the of the 4,928 cooling towers have been inspected. According to the New York City Department of Health and Mental Hygiene, 1,167 total have been inspected as of June.

This represents a considerable drop in inspections. In 2024, the first three months of the year saw 968 inspections, and as of June 2024, 1,795 cooling towers were inspected, according to city data. See all the data here.

According to city law, these cooling towers must be inspected every three months for Legionella bacteria, which causes the deadly flu-like illness.

The cases are concentrated in five Central Harlem ZIP codes—10027, 10030, 10035, 10037, and 10039—according to the Health Department, which is now saying the outbreak is not expected to spread beyond the affected area.

According to the New York City Department of Health and Mental Hygiene, officials have now tested all cooling towers in the affected neighborhood and instructed owners of any buildings with positive results to begin cleanup efforts within 24 hours.

The city first detected the outbreak on July 25, Patch previously reported.

Officials emphasized that the outbreak is not linked to any building’s plumbing system. Residents in the affected ZIP codes can safely drink tap water, bathe, shower, cook, and use air conditioning as usual.

City officials urge anyone who has been in the area since late July and is experiencing symptoms like fever, cough, muscle aches or difficulty breathing to seek medical care right away.

A spokesperson for the New York City Department of Health and Mental Hygiene said that the lower inspection numbers are due to staffing shortages, and that the department is working to fill open positions.

To see the latest data on Legionnaires' disease, click here.

For questions and tips, email Miranda.Levingston@Patch.com.

This article has been updated with additional information from the health department.