A Legionnaires' disease outbreak in Central Harlem has now caused four deaths and sickened 101 people, New York City health officials confirmed.

The bacteria that cause the illness, called Legionella, were found in 12 cooling towers across 10 buildings, including NYC Health + Hospitals/Harlem.

Cooling towers help regulate temperature in large buildings, but if they are not cleaned properly, bacteria can grow and spread through mist in the air.

"As of today, 11 of the 12 cooling towers in Central Harlem that tested positive for Legionella bacteria have completed remediation, and by tomorrow, all towers will have completed remediations," New York City Mayor Eric Adams said on Aug. 14. "New Yorkers should know the air is safe to breathe, and we are seeing declining numbers of new cases each day."

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