Its substantive response to the crisis at hand was strong, but it has withheld some basic information from the public. An upcoming City Council oversight hearing will look into a host of issues.
Aug. 6, 2026 — Last Friday, July 31, Dr. Alister Martin, the commissioner of the New York City Department of Health and Mental Hygiene (DOHMH) announced that the Legionnaires’ disease outbreak on Manhattan’s Upper East Side was over. “The source of bacteria exposure causing this cluster [presumed to be from one or more cooling towers] has been cut off,” he said.
The City Council Committee on Health, chaired by Council Member Lynn Schulman, will be holding an oversight hearing on Sept. 8. It promises to be a wide-ranging hearing.
Ironically, the substantive response of DOHMH once the outbreak was discovered — prompt PCR testing and culture sampling, with full remediation required for any cooling tower that tested PCR-positive, a standard higher than that normally required by DOHMH rules and a requirement stronger than past practice — has yet to be persuasively challenged.
FOIL it if you want it
Now that DOHMH has culture results back from the New York State laboratory that analyzes the culture samples — 59 cooling towers in 58 buildings came back positive for legionella bacteria — it knows more specifics about the bacteria found than had previously been the case. This includes whether the legionella found in a tower included the species (Legionella pneumophila) and the serogroup (Lp-1) that is generally responsible for causing illness.
More than that, lab results tell DOHMH the concentration of bacteria found. Those concentration levels are important. That’s not because they provide a clue to which cooling tower or towers caused illness in the 92 people confirmed to have been infected with Legionnaires’ disease as a result of the Upper East Side community cluster. Matching bacteria from specific cooling towers to the bacteria found in infected patients is an entirely separate process involving genetic testing of the bacteria (both sequence-based testing and whole-genome testing). At a July 31 press briefing, Martin said that results of the genetic testing were expected late in August. (In some community clusters, a match is never made.)
What the concentration levels can do is provide information on the efficacy of a building’s Legionnaires’ control protocol and on one of the risk factors for the spread of Legionnaires’ disease. In other words, the information is highly relevant to DOHMH itself, to the public, and to the ability of the City Council to make assessments both about building compliance and about agency oversight.
I spoke again to Janet E. Stout, a leading expert on Legionnaires’ disease, who has previously helped me try to understand the science relating to Legionnaires’ and cooling tower outbreaks.
Stout explained that, especially under New York City’s monthly self-testing regime, there is ample opportunity for a building to respond to any uptick in legionella bacteria in a cooling tower. That’s what DOHMH’s rules are designed to deal with in the normal course. Depending on the concentration of legionella bacteria, different types of corrective action are required. (See the table, below).
If legionella bacteria get to the “Level 4” concentration (equal to or greater than 1,000 “colony forming units,” or “CFUs,” per milliliter), Stout said, that is indicative of a serious failure of the building’s implementation of the rules designed to keep legionella under control. When thinking about the scope and degree of non-compliance, it makes a difference, for example, whether only two of the 59 culture-positive towers had Level 4 concentrations, with the others distributed among Levels 1, 2, and 3, or whether only a small minority of cooling towers were at Levels 1, 2, or 3, with a substantial number at Level 4.
It is a “good question” to be posing, Stout said, adding that disclosure of the information helps in the understanding of the extent to which “people are not doing what they should be doing,” and of the extent to which “more needs to be done from a policy point of view to encourage them to do it.” See the box at the bottom of this page for a discussion of how the concentration of legionella bacteria can affect risk to the public.
I had asked DOHMH to provide information on legionella concentrations in the culture-positive cooling towers, but the agency declined, providing a non-responsive explanation. If you want the information, an agency spokesperson said, you can file a Freedom of Information Law (FOIL) request.
So, I did. Time will tell when and whether the agency complies or resists the FOIL request.
Regardless of its response, more questions are coming. A spokesperson for Speaker Menin said that it was expected that the information that DOHMH does and does not share with the public during outbreaks would be part of what gets explored at the hearing.
Other information withheld
I had previously asked DOHMH for information on the overall number of Legionnaires’ patients who had to be treated in the ICU, and the overall number who had to be put on a ventilator. DOHMH, citing a vague and unconvincing “patient privacy” rationale, did not provide that information. With the outbreak over (except, importantly, for five patients who remain hospitalized), that information is still not public. I included this information in the FOIL request.
Finally, I sought something in the nature of a “heat map” so that the public could see in a general (non-individually-identifiable) way where the 92 confirmed Legionnaires’ patients clustered (if they did cluster).
As with concentration, this is not some attempt to play amateur detective in trying to determine the cooling towers that were the source or sources of infection, but rather to provide the public and any oversight bodies with basic information as to what happened — as well as how well whatever pattern or patterns that may exist correspond to DOHMH’s area of investigation.
Here, again, DOHMH’s answer was unresponsive and the information was not provided. I therefore included in the FOIL a request for sufficient information (partially redacted to ensure patient privacy) to be able to construct the desired heat map.
Carrots and sticks
At his press briefing, DOHMH’s Martin said that, of more than 80 inspections conducted on the Upper East Side as a result of the outbreak, more than 60 percent of the inspections resulted in at least one violation. What he characterized as the “two most concerning locations,” where the non-compliance “risks the safety of New Yorkers,” were the subject of multiple violations, resulting in approximately $10,000 in fines for each building.
I asked Martin whether that level of fine for the two biggest offenders was sufficient to deter this kind of threat to public health. Martin said that DOHMH was eager to identify ways to push the overall regulatory apparatus to maintain a strong posture, and was looking forward to continuing discussions with the City Council to determine what was possible.
It would be very surprising, indeed, if enhancement of fines were not part of the package that emerges from the Council’s oversight process.
I asked Stout about the issue of increasing compliance and she described a program of both sticks and carrots as being the best way to proceed. Yes, it is important to enhance fines to a level where they provide a meaningful deterrent to non-compliance (that is, brandish a bigger stick). But at the same time, she said, the baseline of a monthly testing regime (new in 2026) provides an opportunity for carrots, too. Buildings operating a cooling tower who have been fully compliant for a year could be allowed to shift to a bimonthly testing schedule, for example. Doing so would reward full compliance.
Some building owners would be incentivized to remain fully compliant so as not to be thrown back into the monthly testing cycle. Those building owners who, on the other hand, took the reduced testing schedule as a license to relax vigilance would find themselves back in the world of monthly testing . . . and sticks.
DOHMH capacity
The outbreak generated substantial discussion and criticism of DOHMH staffing levels in relation to cooling tower oversight, and also criticism of the volume and cadence of pre-outbreak inspections.
Remapping Debate took a broader look, previously reporting on the “unspoken big picture,” namely that a public health department doesn’t simply need “just enough” staff to deal with the day-to-day, it needs a staffing level that provides sufficient buffer to be able to surge response at crisis moments. We reported that one public health expert observed that he thinks that “the health department’s incident command system is balancing half a dozen things right now. And that is well above any health department’s baseline capacity for response.
Speaker Menin’s spokesperson told me that DOHMH staffing is another topic that can be expected to be explored at the September Health Committee oversight hearing.