Mold in NYC Apartments: Complaints and Violations Trend

Mold complaints to HPD grew from 28,155 in 2019 to 42,574 in 2024, a 51.2% rise, then fell to 38,477 in 2025. About one in four 2025 mold complaints ended with HPD issuing violations. In about four in ten, an inspector looked and found no violation, and in about three in ten HPD could not complete an inspection.

What counts as a mold complaint and a mold violation

Tenants report mold through 311, and HPD logs each condition as a "problem" within a complaint. We count problems HPD filed under the minor category "MOLD". A mold violation is one an inspector writes; we count violations whose description mentions mold (and exclude ones that only mention molding, the trim). In 2025, 46.1% were Class A, 45.5% Class B and 8.5% Class C. See HPD violation classes explained.

Under Local Law 55, owners of buildings with three or more apartments must keep units free of mold, fix the underlying cause such as a leak, and inspect units each year. In buildings with 10 or more units, mold over 10 square feet must be handled by a New York State licensed assessor and a licensed remediator who is independent of the assessor (source: HPD, Indoor Allergen Hazards).

The trend: up sharply through 2024, lower in 2025

Complaints and violations moved together. Both dipped in 2020, climbed to a peak in 2024 (violations were roughly flat between 2021 and 2022), and fell in 2025. Violations went from 28,205 in 2019 to a peak of 47,545 in 2024, then 38,760 in 2025. Even after the 2025 dip, complaints were 36.7% above 2019 and violations were 37.4% above 2019.

The two lines should not be read as "complaints that became violations". One inspection can produce several mold violations (one per room or wall, for example), and inspectors also write mold violations during inspections for other problems. That is why violations can outnumber complaints in some years.

What happened to 2025 mold complaints

HPD records an outcome on each complaint problem. Grouping the 2025 outcomes gives a more direct answer to how many complaints led to violations. Of the 25,697 problems where an inspector got in and recorded a finding, 37.8% resulted in new violations.

The "could not inspect" group is large. HPD's status messages in this group say the inspector was unable to complete the inspection or could not get into the rooms, and ask the tenant to file a new complaint if the condition continues. If you report mold, being reachable and home for the inspection matters. Our 311 complaint guide covers how.

Where: the Bronx files the most

The Bronx had 13,501 mold complaint problems in 2025, 35.1% of the city total, followed by Brooklyn with 11,304. Manhattan grew the fastest in percentage terms: 4,775 in 2019 to 8,150 in 2025, and it was the only borough where 2025 stayed close to its 2024 level. These are raw counts and are not adjusted for the number of rental apartments in each borough.

Of the 38,760 mold violations issued in 2025, 13,143 (33.9%) were still open on HPD's record on 2026-10-12. An open violation means the record has not been closed. The owner may have made the repair without certifying it.

The Underlying Conditions Program

When mold and leak violations keep coming back in many apartments of one building, HPD can order the owner to find and fix the source under the Underlying Conditions Program (Local Law 6 of 2013). Buildings qualify based on the share of units with uncorrected Class B or C mold or leak violations issued in the past year, and HPD says it selects about 50 to 100 buildings a year. The owner generally has four months to correct the conditions (source: HPD, Underlying Conditions Program).

The 2025 group of 124 buildings with 4,590 units is the largest in the dataset, which covers 700 building orders since 2013. As of 2026-10-12, 133 buildings were listed as active and the rest as discharged. The dataset has no orders dated 2020 or 2021, and only 6 in 2023; its latest order is dated 2025-09-26.

Limits of this data

• Complaint counts are problems, not people. One complaint can include more than one problem, and several tenants can report the same condition. In 2025 the 38,477 problems came from 37,718 complaints.
• Complaints depend on tenants calling 311. A rise can reflect more awareness or easier reporting as well as more mold.
• The violation count uses a text search for "mold". Violations about mold written with other wording are missed.
• Outcome buckets reflect the status on 2026-10-12. Statuses for recent complaints can still change.