Mold - NYC Health (2024)

Clean Up Safely After a Flood

Flood water may contain bacteria, petroleum and chemicals. Mold can grow in a flooded home that is not properly cleaned and dried out.

Learn how to safely clean your home after a flood:

• Healthy Homes: Mold (PDF)
  Other Languages: Español | 繁體中文
• CDC Infographic: Eight Tips to Clean Up Mold
• Guidance for Building Owners and Property Managers After Flooding
• Severe Weather Resources

Mold can be different colors, including gray, black, green, yellow and orange. It may look furry, slimy or powdery. Some mold has a musty, stale or earthy smell.

Mold usually grows in wet or damp places. It can grow on paper, fabric, wallpaper glue, sheetrock, wood, soap scum, leather and other surfaces. It can grow where there is water, high humidity or damp conditions. Mold grows faster in warm temperatures and high humidity.

Owners of buildings with three or more apartments, or buildings of any size where a tenant has been diagnosed with moderate or severe persistent asthma, are required to keep tenants’ homes free of mold. This includes safely repairing underlying problems like water leaks.

• If the area of mold to be fixed is more than 10 square feet in buildings with 10 or more apartments, or in buildings with 25,000 or more square feet of non-residential floor area, building owners or managers are required to use New York State Department of Labor-licensed mold assessment and remediation (or abatement) workers.

  For these conditions, licensed mold assessors, remediators and abatement workers are required to file paperwork online through the NYC Department of Environmental Protection’s Mold Abatement website.



• For areas to be fixed that are 10 square feet or less, follow the steps in the Mold Prevention and Removal section.

To protect against fraud, New York State law prohibits the same licensed worker from carrying out both the assessment and remediation on a property. For more information on these requirements, including a list of licensed mold assessors and remediation workers, visit the NYS Department of Labor’s Mold Program website.

For more information on controlling and removing mold hazards email [email protected] or call 311 and ask for the Healthy Neighborhoods Program.

The best way to prevent mold is to remove water and moisture sources.

1. Fix leaks. If you are a tenant, report the problem to your building manager.
2. Dry out wet and damp areas like bathrooms, kitchens and basem*nts. You can monitor humidity with a humidity monitor from a hardware store.

• Use an exhaust fan that vents to the outside while cooking or bathing.
• Open windows to let in fresh clean air from outside.
• Only open windows when outdoor air pollution is low. If you live near a high-traffic area, consider where windows are located before opening them. Go to Airnow.gov to check air quality in your area.
• Make sure window guards are installed if a child younger than 11 years old lives or spends time in the home. Screens are not a substitute for window guards.
• Use a dehumidifier or air conditioner to help lower indoor humidity.
• Run your air conditioner on ‘recirculation’ mode on bad air quality days so it does not bring in air from outside.

To safely remove mold:

1. Keep children and pets away until area is cleaned.
2. Use water and soap (or dish detergent) to clean mold on walls or other hard surfaces.
3. Wear waterproof gloves while cleaning.
4. Dry the cleaned area completely.
5. Wash and dry (or throw away) sponges or rags used to clean mold.

Also see: CDC Infographic: 8 Tips to Clean Up Mold.

If the mold returns quickly or spreads after cleaning, there may be an underlying problem, such as a water leak. Report the mold problem to your landlord.

If the problem isn’t fixed in a timely way, or if the mold is in a non-residential location, submit a complaint online or call 311.

If large areas of mold are present, you may need outside help such as a professional mold abatement company. Be sure your contractor is licensed and follows NYS Labor Law requirements.