New York City is to overhaul the way it monitors cooling towers and responds to Legionnaires’ disease after an outbreak on the Upper East Side killed 11 people and sickened 94, Mayor Zohran Mamdani has announced. The plans include a public map of registered cooling towers, tougher enforcement and closer co-operation between the city’s health and buildings departments. ([cbsnews.com](https://www.cbsnews.com/newyork/news/upper-east-side-legionnaires-disease-death-toll-august-2026/))
The map, due to be launched next spring, is expected to show the location of each registered tower, its inspection history and whether the building is complying with Legionella testing requirements.
Officials also intend to speed up laboratory testing for the bacteria and take swifter action against building owners who fail to meet their legal obligations. The aim is to identify potential sources of contamination earlier and reduce delays in dealing with them.
New York’s Legionnaires’ disease strategy
The measures follow two serious outbreaks in New York. The Upper East Side cluster centred on the Carnegie Hill and Yorkville neighbourhoods, while a separate outbreak in Central Harlem last year left 118 people ill and seven dead. ([nyc.gov](https://www.nyc.gov/site/doh/about/press/pr2026/new-cooling-tower-legionella-testing-regulations-take-effect.page))
Cooling towers, commonly found on the roofs of large commercial buildings, use water to remove heat from air-conditioning and refrigeration systems. If contaminated, they can release fine droplets containing Legionella into the outside air, which can then be inhaled.
Under the city’s more aggressive approach, buildings with an initial positive PCR test are ordered to drain, clean and disinfect their towers immediately, rather than waiting for a confirmatory culture result. That process can take up to two weeks. ([nyc.gov](https://www.nyc.gov/mayors-office/news/2026/07/mayor-mamdani-takes-aggressive-action-to-address-upper-east-side))
New York City’s health department said in July that it had tested more than 180 cooling towers during the Upper East Side investigation and ordered 83 buildings to carry out cleaning and disinfection. Fifty-nine towers were later found to contain live Legionella bacteria, although officials have continued investigating the precise source of the outbreak. ([nyc.gov](https://www.nyc.gov/site/doh/about/press/pr2026/health-department-declares-ues-legionnaires-exposure-has-ended.page))
The city said 81 per cent of cooling towers were complying with sampling and testing rules in the latest figures cited by the mayor’s office. However, more than half of about 800 inspections carried out in recent months resulted in at least one violation.
New citywide regulations that came into force on May 8 require operating cooling towers to be tested for Legionella every 31 days, replacing the previous 90-day schedule. The health department has also been given an additional 13 million dollars in funding and plans to hire more inspectors. ([nyc.gov](https://www.nyc.gov/site/doh/about/press/pr2026/new-cooling-tower-legionella-testing-regulations-take-effect.page))
Legionnaires’ disease is a form of pneumonia caused by Legionella bacteria. It is not generally spread from person to person, and people at greater risk include adults aged 50 and over, smokers and those with chronic lung disease or weakened immune systems. ([nyc.gov](https://www.nyc.gov/site/doh/about/press/pr2026/new-cooling-tower-legionella-testing-regulations-take-effect.page))
