City Proposes Stronger Legionnaires’ Rules for Cooling Towers, Amid Outbreak

An ongoing outbreak of Legionnaires’ disease that struck Harlem in late July, killing three people, appears to be slowing down somewhat. Now, it’s come to light that the city has proposed rules that would tighten reporting standards for cooling towers that could harbor Legionella bacteria. The current outbreak, as well as other prominent NYC outbreaks, have been traced to such rooftop structures.

Legionnaires’ disease, a form of severe pneumonia, is caused by exposure to water vapor containing the Legionella bacteria. Although it is not contagious from human to human, epidemiologists have pointed out that it has an average mortality rate of 10 percent, despite many healthy people not contracting serious cases upon exposure.

The latest figures from the city’s Health Department reveal that a total of 90 people have been infected so far, up from 82 last week, with hospitalizations on the decline. The latter number previously marked a sharp jump from only 22 cases in the first couple of weeks of the outbreak, which has been concentrated in five ZIP codes: 10027, 10030, 10035, 10037, and 10039.

Since the disease thrives in warm water, cooling towers—which contain hot water that is then, as the name suggests, cooled and circulated—pose a unique risk to public health when it comes to Legionella. The disease can also spread via humidifiers, hot-water tanks, and evaporative condensers.

Hot tubs and whirlpool spas are also prone to becoming hotspots, if not properly monitored. Window-unit air conditioners, such as those in residential apartments, are not at risk, the city Health Department said.

The proposed rules around cooling towers, which are part of the NYC Health Department’s regulatory agenda for the 2026 fiscal year, appear to mostly orient around strengthening detection standards. They were reportedly in the works before the latest outbreak, CNN reported. The rules would go into effect in the spring of next year, if adopted.

Under the rules, Legionella cooling-tower samples would be “conducted by a laboratory certified by the New York State Environmental Laboratory Accreditation program.” Currently, samples are supposed to be tested “immediately,” which the rules deem too vague; more definitive time frames, which have yet to be specified, would be established by the new rules.

The proposed rules also mention unspecified and readjusted penalties, which would be imposed on building owners who fail to have their cooling towers properly inspected for Legionella. This would ostensibly be done through an existing registration and compliance system. Currently, building owners can receive fines ranging from $500 to $2,000 for failing to comply.

Quite relevantly, a new report in Gothamist shed light on a precipitous decline in inspections in recent years, with this year representing a record low. The report notes that back in 2017, the year that the compliance system began in earnest, there were 5,200 cooling towers inspected and 48,000 violations handed out.

As of June of this year, however, only 1,167 inspections occurred. This is despite a generally persistent year-over-year increase in Legionnaires’ outbreaks that began this century, according to the Centers for Disease Control. A spokesperson told Gothamist that staffing issues were to blame.

Legionnaires’ gets its name from its first recorded outbreak, which occurred in 1975 at a gathering of American Legion members at a Philadelphia hotel. A total of 221 people were infected, and 34 people died. One of the worst outbreaks in New York City occurred in the Bronx back in 2015, leading to 138 cases and 16 deaths. The outbreak was traced to a cooling tower.