The New York City ZIP codes with the most air quality and mold complaints

We used data from 311 calls to find where in NYC people are struggling with bad air quality and mold indoors
Updated on May 27, 2024
Written by
G. John Cole
Graeme has been a Senior Writer for our parent company (NeoMam Studios) since 2013. At HouseFresh, he writes in-depth articles to accompany the original studies and data visualizations produced in partnership with the NeoMam team.

New York’s 311 helpline sees it all. In 311’s 20-year history, New Yorkers have called the number over 500 million times to get help and information from non-emergency City services. The 311 call records database has become a virtual portrait of New York City — from the point of view of what its inhabitants feel the need to complain about.

As often as not, the bizarre 311 calls make the headlines. These quirky inquiries capture the unique character of the Big Apple and its inhabitants. But 311’s true purpose is to improve home and street life for locals. And so it becomes the battleground for more serious issues, from a police parking abuse case that remains unresolved after 232 calls or a decline in reports of rat sightings that may be down to New Yorkers “just getting used to them.”

In a tight and industrious city like New York, health issues like mold and air quality have the potential to impact every area of life. But all of New York City is not the same, and the 311 calls database reveals a very uneven spread of air quality and mold complaints from borough to borough. To see which ZIP codes are the worst hit, we at HouseFresh analyzed call volume from the 311 database to rank and map the neighborhoods with the most complaints in New York.

What we did

We analyzed data from the NYC Open Data website about 311 calls in the 12 months from November 2022 to October 2023. We used this data to identify the New York boroughs and ZIP codes with the most complaints (per 10,000 people) about mold, indoor air quality and outdoor air quality. We then compared these to the equivalent figures from November 2017 to October 2018 to see how the level of complaints has changed in the past five years.

Key Findings

  • The Bronx has the most mold complaints, with 73.31 calls per 10,000 inhabitants per year.
  • Manhattanites make 12.12 indoor air quality complaints per 10,000 people per year, the most of any borough.
  • Manhattanites also make the most outdoor air quality complaints: 13.47 per 10,000 people per year.
  • However, indoor air quality complaints in Queens have risen by 82.28% over five years, the biggest change in our study.

The places in New York City with the most and least mold complaints

Molds are a type of fungus, and they thrive on moisture. They reproduce by spreading spores in the air and can damage the surfaces on which they grow.

Although molds are an important part of the natural environment, when they spread indoors, they can lead to allergic reactions such as sneezing, rashes and dizziness. Molds can also lead to more severe reactions, such as asthma, and are particularly harmful to children, the elderly and those with respiratory problems.

Worried about mold in your home? There are easy ways to test for it.

First, we mapped the New York boroughs with the most mold complaints per 10,000 inhabitants. The Bronx is way ahead with 73.31 complaints, practically twice that of second-placed Manhattan. This is despite complaints in Manhattan rising by 32.59% over the past five years.

The Bronx is home to a dense level of public housing, an area where mold management can be slow and inconclusive. Some 8% of children living in the Bronx are living with chronic lung disease, and in the South Bronx, asthma rates are eight times the national average. The Bronx has long been New York City’s leading borough for mold, and mold reports have risen by 17.12% over the past five years.

Next, we zeroed in on the precise neighborhood ZIP codes where mold reports are most and least common. Sure enough, the two outliers are in Manhattan — specifically, in the 10030 ZIP code of Harlem — and 10474 in the Bronx, at Hunts Point.

Hunts Point has become known for a number of buildings kept in a poor state of repair, although much of this is the responsibility of landlords rather than the city. “It is draining to have to fight for something that’s really just the right that should be given to you,” says Grace Medico Cuapio, a Hunts Point organizer for Banana Kelly, a community improvement association.

The neighborhood with the tenth most complaints about mold is NYC 10040, covering parts of Washington Heights and Inwood in Manhattan. Some 99.25 complaints per 10,000 people were made here last year, an increase of 200% from 2017 to 18 figures. This makes it the ZIP code where complaints have risen most dramatically over the past five years.

Washington Heights resident Jose Jimenez has had mold growing in his apartment for 20 years, with a succession of landlords either ignoring the damage or painting over it temporarily. “It is no secret there are landlords who neglect units occupied by long-term tenants, as part of a broader strategy to increase turnover and displacement,” claims Jason Wu, the attorney representing Jimenez in court. Painting over mold covers the problem, but if moisture remains, the mold will reappear and continue to grow.

The places in New York City with the most and least indoor air quality complaints

Indoor air quality is affected by a number of issues that New York residents can complain about, including:

  • Dust from building work.
  • Chemical odors, including soot and vapors, when originating in the building.
  • Dry cleaning odors from a neighboring home or business.
  • Sewage, feces and poor ventilation.
  • Smoke, dust and airborne debris from a neighborhood fire.

Manhattan is the leading district for indoor air quality complaints, with 44.6% more complaints per 10,000 inhabitants than second-placed Brooklyn. And this is despite complaints from Queens, the Bronx and Brooklyn rising significantly more than Manhattan over the past five years. There were 12.12 complaints per 10,000 people in Manhattan last year.

Governor Kathy Hochul announced a $3.5 million boost in state funding for environmental justice initiatives in November 2023, with substantial investment in air quality monitoring and improvement. “Both the community impact and air monitoring grants support the crucial work of not-for-profit, community-based organizations that develop a wide variety of projects that drive positive change and improved environmental outcomes in their communities,” said Environmental Conservation Commissioner Basil Seggos.

The 10282 ZIP code, representing the area between Battery Park and Rockefeller Park, just north of the 9/11 memorial in Manhattan, is New York’s worst area for indoor air quality complaints. Here, complaints are made at just over double the citywide average rate. While developers in this area pioneered green building in New York, Battery Park remains known for its high-density population. The contrast between the area’s famed green spaces and busy living spaces may draw attention to poor air quality when it occurs.

Meanwhile, residents in the New Hyde Park area at ZIP code 11040 made just 0.23 per 10,000 people last year. In a previous study, HouseFresh discovered that New Hyde Park also receives the fewest sanitation-related 311 complaints, suggesting that the area is kept very clean — or that the locals don’t like to complain.

Two ZIP code areas have seen an increase of well over 1,000% in complaints made about indoor air quality. Complaints in Woodhaven (ZIP 11421) rose by 4100%, while in Middle Village (11379) they rose by 1480%. Ironically, Woodhaven nestles up alongside the Ozone Park neighborhood — the area was named before the ozone gas was properly understood, back when it was associated with fresh, healthy air. In fact, ozone — the gas, not the place — smells somewhat bleach-like.

Additionally, the Glendale Superfund site, just north of the Woodhaven neighborhood, “has been known to send a plume of toxic tetrachloroethylene” skywards due to industrial activity when a knitting mill occupied the site nearly sixty years ago. Although the Department of Health has insisted there is no continued danger, the issue continues to rear its head due to an ongoing remediation process with locals.

The places in New York City with the most and least outdoor air quality complaints

Outdoor air quality can affect the whole city at once. The Department of Environmental Conservation uses the Air Quality Index (AQI) to measure safety levels. 

Citywide Air Quality Action Days are when the AQI is between 101-150. This can be due to:

  • Neighborhood fires.
  • Incoming wildfire smoke.
  • Chemical odors.
  • Vehicle emissions.

As with indoor air quality, Manhattan is the leading borough for outdoor air quality complaints — in this case, with 52.42% more than Brooklyn. While the Bronx is the third worst area for indoor air complaints, Bronx residents make the fewest complaints (per 10,000 people) about outdoor quality out of any of the five boroughs.

Amidst the June 2023 wildfires, New York City reached an AQI of 342, making it temporarily the worst city in the world for air quality. “This may be the first time we’ve experienced something like this of this magnitude,” said Mayor Eric Adams. “Climate change is accelerating these conditions. We must continue to draw down emissions and improve air quality and build resiliency.”

Multiple lower Manhattan ZIP codes are among those making the most complaints of all. The Tribeca Festival organizers provided masks to its staffers and considered postponing events in June 2023 as worsening conditions impacted incoming flights.

SoHo occupies much of the 10012 ZIP code, where the fourth-highest number of complaints were made. Workers at the SoHo branch of outdoor retail chain REI “successfully pressured management to close,” but only after the AQI levels reached over 400, according to a union Instagram post. “Before that, they held our reduced wages over our heads, forcing workers to choose between our own safety and our livelihoods,” claimed the workers.

A Bronx ZIP code, 10462, has shown the most significant growth in complaints over the past five years. This ZIP covers Parkchester, Westchester Square and Castle Hill. Across the Bronx, the Co-op City area has seen the largest reduction in complaints.

Some four out of five Parkchester homes have air conditioners installed, according to the New York City Department of Health and Mental Hygiene. The air in Parkchester was found to contain 7.6 micrograms of fine particulate matter (PM2.5) per cubic meter — a little over the city average and a little under the Bronx average.

How to protect yourself from mold and common air quality issues at home

Mold and poor air quality can significantly damage your health, and researchers have shown air pollution to have a negative impact on the academic performance of children. Many issues that arise require civic or corporate intervention on a grand scale. But there are achievable steps you can take around the home to protect your family from the effects of these public health issues.

1. Control indoor humidity. Keep humidity levels well below a dew point of 50° by installing a dehumidifier of an appropriate size and capacity for the room where mold is an issue. Take short, cool showers when possible.

2. Ventilate. Use exhaust fans in the bathroom and kitchen when possible. Ensure that the HVAC system is turned on (or windows opened) following cleaning activities such as mopping or during humid weather conditions.

3. Clean moldy areas. Routinely clean areas where mold builds up, such as shower curtains, bath mats and the areas around them. However, bear in mind that a professional contractor may be a better choice for cleaning up significantly moldy areas.

1. Limit exertions and excursions. Try not to go outside on Air Quality Action Days, and avoid strenuous activities to minimize bad air intake.

2. Wear a mask. City officials and health experts suggest wearing an N95 or KN95 face mask to filter out dangerous particles.

3. Avoid polluting activities. NYC 311 recommends that you don’t mow your lawn, use aerosol products, use a fireplace or drive a car on bad air days.

1. Use natural cleaning products. Keeping a clean home helps maintain clean air levels, but using products that contain certain chemicals and gasses can worsen things. Try to choose EPA Safer Choice products where possible.

2. Maintain your HVAC system. Hire a pro or learn how to clean air vents, and be sure to check them at least once a year.

3. Choose the right air purifier. Purifiers with HEPA (high-efficiency particulate arresting) filters are more effective at trapping dangerous particles. HouseFresh rigorously tested 54 air purifiers in 2023 and identified the 11 best air cleaners in terms of performance, long-term costs, sound and ease of use. 


To identify the New York neighborhoods and ZIP codes with the highest number of 311 complaints per 10k population for mold, indoor air quality and outdoor air quality, we analyzed 311 data for the most recent 12 months from the NYC Open Data website (November 2022 to October 2023).

For each complaint type, we recorded complaint counts for each borough and ZIP code between November 2022 and October 2023. We then repeated this process for the corresponding time period five years prior (November 2017 to October 2018).

This allowed us to calculate the boroughs and ZIP codes with the most and fewest complaints per 10k population for each metric and the five-year change in complaints per 10k.


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About the author

G. John Cole

Graeme has been a Senior Writer for our parent company (NeoMam Studios) since 2013. At HouseFresh, he writes in-depth articles to accompany the original studies and data visualizations produced in partnership with the NeoMam team.

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