A recent cluster of Legionnaires’ disease has led to one person’s death. Officials said 30 people have been sickened, up from 22 earlier in the week, according to the New York City Health Department

The disease is spread by breathing in water vapor containing Legionella bacteria, which are known to grow in cooling towers, whirlpool spas, hot tubs, humidifiers, hot water tanks and condensers of large air-conditioning systems.