A large outbreak of Legionnaires’ disease in the Bronx in 2015 prompted NYC to enact law and
NYS to propose emergency regulations on the registration and maintenance of cooling towers.
This paper describes the fundamental characteristics of airborne vs. waterborne outbreaks and
discusses the Bronx outbreak from those perspectives. Ultimately a case is made that these new
regulations will not have a measurable impact on reducing the incidence of Legionellosis.