Lead Paint on Old Windows: How to Know If It's a Hazard

In a house built before 1978, painted windows are a common source of lead dust, because the sashes rub and bump against their frames every time they open and close. HUD’s lead guidelines name old windows with deteriorated lead-based paint and high levels of leaded dust on window sills and troughs as common findings in risk assessments. The way to know about a specific house is testing by a certified professional, not the look of the paint.

Why windows in particular

Windows combine the two conditions that turn old paint into dust: friction and deterioration.

• Friction surfaces. EPA’s regulations define a friction surface as one subject to abrasion or friction, and name certain window surfaces as an example (40 CFR 745.63).
• Condition matters. EPA’s 2024 fact sheet says lead-based paint in good condition is usually not a hazard, while deteriorating paint that is peeling, chipping, chalking or cracking is.
• Where the dust collects. Dust settles on the interior window sill, the ledge that projects into the room, and in the window trough. EPA defines the trough, for a typical double-hung window, as the part of the exterior sill between the interior sill and the storm window frame. Without a storm window, it is the area that receives both sashes when they are lowered.

Under EPA’s hazard rule, lead-based paint on a friction surface that is subject to abrasion counts as a paint-lead hazard when the dust on the nearest horizontal surface beneath it, such as the window sill, reaches the dust-lead hazard level (40 CFR 745.65).

Which homes are likely to have it

The federal government banned lead-based paint for residential use in 1978, according to EPA, so any lead paint in a home is at least that old. The likelihood rises with age. EPA’s figures:

• 87 percent of homes built before 1940 have some lead-based paint.
• 24 percent of homes built between 1960 and 1978 do.
• 30.9 million pre-1978 houses still contained lead-based paint in a 2021 analysis EPA cites, and 3.8 million of them had a child under six living there.

For any pre-1978 home, the first option EPA lists is to assume lead-based paint is present and take precautions. The second is to hire a certified professional to check.

What EPA’s newer dust rule changed

EPA tightened its lead dust standards in a final rule published on November 12, 2024. It took effect on January 13, 2025, and compliance with the new levels began on January 12, 2026, in the jurisdictions EPA administers directly.

• Reportable level. A dust-lead hazard used to mean 10 micrograms of lead per square foot on floors and 100 on window sills. Since January 12, 2026, it is any reportable level of lead, as measured by a laboratory recognized under EPA’s National Lead Laboratory Accreditation Program.
• Action levels after abatement. The dust that may remain after an abatement dropped to 5 micrograms per square foot on floors, 40 on window sills and 100 in window troughs.
• New names. EPA now calls the two standards the dust-lead reportable level and the dust-lead action level.

EPA explains the change by noting that no safe level of lead in children’s blood has been found. Between the reportable level and the action level, EPA recommends careful cleaning, such as a HEPA-filter vacuum and regular damp wiping of hard surfaces, rather than abatement. At or above the action level, it recommends abatement.

Window sills are one of the two surfaces the rule names, so any reportable amount of lead dust on a sill now counts as a dust-lead hazard.

Inspection, risk assessment or test kit

A risk assessment by a certified professional is what tells you whether lead is a hazard in the home now; an inspection shows only where lead paint is. EPA’s recognition of lead test kits does not cover use by homeowners.

• Lead-based paint inspection. A surface-by-surface investigation that shows whether lead-based paint is present and where. Only certified inspectors or risk assessors may legally perform one, according to EPA.
• Risk assessment. An on-site investigation of the presence, type, severity and location of lead hazards in paint, dust and soil, with suggested ways to control them. Only certified risk assessors may legally perform one. A combined inspection and risk assessment is also possible, and either comes with a written report.
• Test kits. EPA has recognized three lead test kits, but that recognition applies only to use by Lead-Safe Certified renovators. For a homeowner, the options EPA lists are to assume lead is present or to hire a certified inspector or risk assessor.

EPA runs the certification program directly in Alaska, Arizona, Florida, Idaho, Montana, Nevada, New Mexico, New York, South Carolina, South Dakota and Wyoming. The other states run EPA-authorized programs, and certified professionals are found through the state program.

Homeowners can also send paint chip, dust or soil samples to a laboratory recognized under EPA’s accreditation program.

Health: what to raise with a doctor

Lead exposure is a medical question. CDC states that no safe blood lead level in children has been identified, and points to a blood lead test as the way to determine whether a child has been exposed. Parents can ask their child’s healthcare provider whether a test is needed. CDC uses a blood lead reference value of 3.5 micrograms per deciliter.

EPA’s fact sheet lists the risks: in children, lead can cause delayed growth and development, lower IQ, learning problems and behavior problems, and exposure during pregnancy can affect the baby. This page does not give medical advice. Questions about symptoms, testing or results belong with a physician.

What happens to the windows next

A risk assessor’s report leads to one of two paths, EPA says: abatement, which permanently removes the hazard, or continued maintenance of the paint in place with regular checks.

HUD’s guidelines draw a distinction that matters for window projects. Replacing windows in order to control lead hazards is abatement. Replacing them as part of a renovation can still reduce hazards. In that case, a firm certified under EPA’s or the state’s Renovation, Repair and Painting rule sets up dust containment, removes and disposes of the old window, and carries out cleaning and cleaning verification.

When to bring in a professional, and what to ask

EPA lists the situations that call for a certified risk assessor: a child diagnosed with lead poisoning, young children living or about to live in a pre-1978 home, a planned remodel that will disturb old paint, renting or buying an older home, and any concern about exposure. With some exceptions, sellers and landlords of pre-1978 housing must disclose known lead-based paint, known hazards and any hazard reports.

Questions for a risk assessor:

• Will you take dust wipe samples from window sills and window troughs, and which recognized laboratory will analyze them?
• Will the report compare results with the current reportable and action levels in effect since January 12, 2026?
• Which windows are the sources, and what control options do you suggest for each?

Questions for a window contractor in a pre-1978 home:

• Is the firm certified under EPA’s or the state’s lead renovation rule, and under what number?
• Is this job a renovation or an abatement, and who does the cleaning verification or clearance testing?

Keep the reports. They answer the next buyer’s questions and the next contractor’s.