Your asbestos test results just arrived. The numbers, acronyms and disclaimers on the page may feel like a foreign language: NAD, trace, PLM, friable, percentages and decimals. Behind every line of that report is a decision with consequences for safety, compliance and cost.
Under EPA rules, any bulk material containing more than 1% asbestos is classified as asbestos-containing material, or ACM. In New York State that threshold triggers regulatory oversight and decides whether you are facing routine monitoring or mandatory abatement. A property owner who misreads the report risks not only a health hazard but fines, a failed inspection and a stalled project.
This guide is about reading asbestos test results line by line: what each field means, what the percentage actually tells you, what NAD and trace mean, how a lab report differs from an inspection report, and what to do next.
How to read an asbestos test report, field by field
An asbestos lab report communicates straightforward information once you know what each field is for. Every compliant report carries these elements:
- Sample identification. Each sample has a number or code and a description of where it was collected, for example “Sample 1, kitchen floor tile” or “Sample 3, basement pipe insulation”. The location matters as much as the result.
- Material description. What the lab received: floor tile, mastic, pipe wrap, plaster, ceiling texture.
- Analysis method. Usually PLM, Polarized Light Microscopy, the EPA standard method for bulk samples. Some reports use TEM, Transmission Electron Microscopy, which is more sensitive.
- Asbestos type. The specific mineral found, most often chrysotile, amosite or crocidolite.
- Percentage. How much asbestos the sample contained, by area or volume depending on method.
- Result. Positive or negative against the 1% threshold, sometimes written as ACM or non-ACM.
A worked example. Here is what a four-sample report typically looks like:
| Sample | Location | Asbestos type | Percentage | Result |
|---|---|---|---|---|
| 1 | Kitchen floor tile | Chrysotile | 3% | Positive, ACM |
| 2 | Kitchen mastic | None detected | 0% | Negative, NAD |
| 3 | Basement pipe wrap | Amosite | 15% | Positive, ACM |
| 4 | Living room plaster | None detected | 0% | Negative, NAD |
In that example the floor tile and the pipe wrap are ACM and must be managed as such. The mastic and the plaster are not. Note that samples 1 and 2 came from the same location: floor tile and the adhesive under it are separate materials and are sampled separately, which is why a kitchen floor can be half positive.
What does NAD mean on an asbestos report?
NAD stands for No Asbestos Detected. It means the laboratory analysed that specific sample and found no asbestos above the method’s detection limit.
Some reports write NADIS instead, meaning No Asbestos Detected In Sample. The two mean the same thing, and the wording is deliberate. NAD is a statement about the material in the lab’s hands, not about your building. It does not mean the room is clear, the floor below is clear, or that the wall cavity nobody opened is clear.
Other abbreviations you may see on the same line:
- ND, not detected, used interchangeably with NAD by some laboratories.
- TR or trace, asbestos present at or near the detection limit, discussed below.
- ACM, asbestos-containing material, meaning the sample tested above 1%.
- f/cc or f/ml, fibres per cubic centimetre or per millilitre, the units used for air results rather than bulk samples.
- PLM and TEM, the two analysis methods.
What the percentage on your report actually means
The single number most people fix on is the percentage, and it is widely misread. The 1% threshold is a regulatory line, not a safety line.
| Result | Classification | What it means in practice |
|---|---|---|
| No asbestos detected | Non-ACM, negative | Nothing found in that sample, at that location |
| Trace, below 1% | Non-ACM, negative | Asbestos is present but under the regulatory threshold |
| 1% or greater | ACM, positive | Regulated as asbestos-containing material |
Is 1% dangerous? Is 2%? Is 10% worse than 3%? Here is the part the percentage does not tell you. A material at 2% and a material at 10% are both ACM and both regulated the same way. The percentage does not scale your risk, because risk comes from whether the fibres can become airborne, not from how many of them are locked in the material. A 2% friable pipe insulation that is crumbling is a more urgent problem than a 15% floor tile in good condition that nobody is touching.
What about a result under 1%? It is legally non-ACM, but read the footnote on your own report. Some project specifications and some jurisdictions treat any detectable asbestos as positive, regardless of percentage. If the result is going into a demolition filing or a contract, check which rule that document is written to before you rely on the 1% line.
What is a trace amount? Trace means asbestos was seen at or near the limit of what the method can quantify. It is technically a detection. Under PLM, a trace result is often the point at which a competent inspector recommends confirming by TEM, because PLM struggles to quantify very low concentrations and in some materials can miss thin fibres entirely.
PLM or TEM: how to choose the right asbestos sample analysis
PLM, Polarized Light Microscopy, is the EPA standard method for bulk building materials and is what most reports use. It is fast, well established and adequate for the large majority of samples.
TEM, Transmission Electron Microscopy, resolves far smaller fibres. It is the method to ask for when PLM returns trace or a result close to 1%, when the material is one PLM is known to struggle with such as floor tile and some vinyl products, and when the result is going to be challenged. Air clearance samples after abatement are also commonly analysed by TEM.
The practical rule: if the number on the page is going to decide whether you spend money or file paperwork, and it sits anywhere near the threshold, the extra sensitivity is worth the cost.
Types of asbestos your report may show
The mineral name on the line tells you what was found and, loosely, where it tends to turn up.
- Chrysotile, white asbestos. By far the most common in US buildings. Floor tile, mastic, joint compound, cement products, roofing, gaskets.
- Amosite, brown asbestos. Frequently found in thermal system insulation and pipe wrap, and in some ceiling and insulating board.
- Crocidolite, blue asbestos. Less common in general construction, found in some sprayed coatings and specialist products.
A report may list more than one type in a single sample. All of them count toward the percentage, and all of them are regulated.
Friable or non-friable, and why it matters more than the percentage
- Friable ACM can be crumbled, pulverised or reduced to powder by hand pressure. Pipe insulation, sprayed coatings and some ceiling materials. Much higher risk of releasing fibres, and the category that drives urgency.
- Non-friable ACM has the fibres bound into a solid matrix. Floor tile, siding, cement board. Generally stable if left alone, but drilling, cutting, sanding or demolition turns non-friable material into a fibre release.
Then assess condition, because a category is not a diagnosis:
- Damaged. Crumbling, water-stained, delaminating or already disturbed. Treat as urgent and restrict access.
- Intact. Sound, sealed and undisturbed. Often manageable in place under an operations and maintenance programme.
- About to be disturbed. Intact today and inside the footprint of a renovation is functionally the same as damaged, because the work will release it.
What a positive asbestos test does and does not mean
A positive result means the tested material contains 1% or more asbestos. It does not mean you are in immediate danger.
What a positive result does NOT mean:
- It does not mean anyone has been exposed to a harmful level of asbestos.
- It does not mean you need to evacuate the building.
- It does not mean the material has to come out. Managing it in place is a legitimate outcome for intact, non-friable material.
- It does not mean every similar material in the building is positive. Results apply to the samples taken.
What it does mean is that the material is now regulated. It cannot be disturbed by unlicensed work, it has to be disclosed in the right circumstances, and any renovation or demolition touching it triggers a defined process.
What if the test comes back negative?
A negative result is good news and it has three limits worth understanding before you rely on it.
- Detection limits exist. Every method has a floor. PLM in particular can under-report very low concentrations and thin fibres in certain matrices.
- The result covers the samples, not the building. A negative on the kitchen floor says nothing about the boiler room. Older buildings routinely hold ACM in areas nobody sampled.
- Future work can uncover more. Opening a wall, lifting a floor or taking down a ceiling exposes materials that were never accessible to sample.
If a negative result is going to support a permit, a sale or a demolition, the question to ask is not “was anything found” but “was the survey scoped to everything the work will touch”.
Lab report or inspection report? They are different documents
People use “asbestos report” to mean two different things, and confusing them is how a filing gets rejected. You may also see the same document called an asbestos evaluation, an asbestos investigation report or an asbestos survey, depending on who wrote it and which jurisdiction it was written for.
| Laboratory analysis report | Asbestos inspection or survey report | |
|---|---|---|
| Produced by | The accredited laboratory | The certified asbestos inspector or investigator |
| Covers | The samples submitted | The building or the work area |
| Contains | Sample IDs, method, type, percentage, result | Scope, drawings or locations, sample results, conclusions, recommendations |
| Answers | Is there asbestos in this material? | What is in this building and what must happen before work starts? |
| Used for | Evidence behind the survey | Permits, filings, contracts, disclosure |
A laboratory result on its own is rarely what a regulator or a filing representative is asking for. They usually want the inspection report, signed by the certified inspector, with the lab results attached as backup. In New York City that distinction becomes concrete at permit stage, where the asbestos assessment is filed on a specific form by a DEP-certified investigator. The ACP-5 form and when your permit needs one covers that filing.
Photo documentation, turnaround and how accurate the result is
Photo documentation. Not all asbestos testing labs provide photo documentation showing the sample as received, and it is a reasonable thing to ask for when a result may be disputed, when the material is being removed before anyone else can see it, or when the report will support a transaction. Ask before the samples are sent, because it cannot be added afterwards.
Turnaround. Standard PLM analysis is typically a few business days, with rush options available at a premium. TEM takes longer. The realistic constraint on a project is rarely the lab bench: it is scheduling the inspector, sampling the whole scope in one visit, and getting the inspection report written.
Accuracy and second opinions. Reasons to seek additional testing include a trace or near-1% result, a result that conflicts with what you can see, a material PLM handles poorly, a sample set that did not cover the full scope of work, and any result that is about to be challenged by a contractor, a buyer or a tenant. Retesting is far cheaper than an abatement commissioned off a wrong number.
Asbestos test results
Send us the report and we will tell you what it means.
UNYSE has read New York asbestos reports since 1993. Our inspectors hold the NYC DEP certification permits require.
Air results and clearance testing
Bulk samples and air samples answer different questions and are reported in different units. A bulk result is a percentage. An air result is a concentration, given in fibres per cubic centimetre (f/cc) or per millilitre (f/ml).
Air sampling matters most at the end of an abatement. Clearance testing after removal must show airborne fibres below 0.01 f/cc before an area can be released for re-occupancy. A completed removal without a passing clearance result is not a finished job, and the paperwork will not stand up. Asbestos air monitoring and clearance testing covers how that phase runs.
Common misconceptions about asbestos test results
- “Negative means there is no asbestos anywhere.” It means no asbestos in the samples taken. Nothing more.
- “A higher percentage is more dangerous.” Condition and friability drive risk. A crumbling 2% is worse than an intact 15%.
- “Under 1% means I can ignore it.” It is non-ACM under EPA rules, but some project specs and jurisdictions treat any detection as positive.
- “Positive means it has to come out.” Intact non-friable material is often best managed in place.
- “One sample covers the material.” Homogeneous areas need multiple samples, and a single negative in a large area is thin evidence.
- “A lab report is my compliance document.” Usually the inspection report is what gets filed.
Compliance thresholds and New York rules
The numbers that carry regulatory weight:
- More than 1% asbestos in a bulk sample classifies the material as ACM under EPA rules, and that classification is what New York State enforcement follows.
- 0.01 f/cc is the airborne clearance level after abatement.
- More than 25 linear feet or more than 10 square feet of ACM to be disturbed makes the work an asbestos project in New York City, which changes which forms are filed and adds a notification period.
New York also requires that the people doing this work hold the right licences: NYSDOL licensing for asbestos handling, and in New York City a DEP-certified asbestos investigator for the survey behind a permit filing. Asbestos testing rules across New York State sets out how the requirements differ inside and outside the city.
Your options when asbestos is confirmed
Removal is one option of three, and it is not automatically the right one.
- Encapsulation. A sealant binds the fibres in place. Suited to intact material in reasonable condition, lower cost and less disruption. The material stays, so it stays on the register and gets monitored.
- Enclosure. A permanent airtight barrier is built around the material. Useful where removal is impractical, for example on structural elements. Again the material remains in the building.
- Abatement. Licensed removal under containment, with air monitoring throughout and clearance testing at the end. The only option that ends the obligation, and the most expensive and disruptive.
Which one is right depends on the material’s condition, whether the area will be disturbed, the building’s future plans and cost. A survey that only ever recommends removal is not an assessment.
Next steps after receiving your asbestos test results
- Do not disturb the material. No drilling, sanding, cutting, sweeping or removal. Restrict access to damaged areas.
- Contain the exposure. Close off the area, shut down air handling that moves air through it, and keep occupants out of damaged friable material.
- Decide the management route. Encapsulation, enclosure or abatement, chosen on condition and on what the building is going to do next.
- Use licensed contractors and file what is required. In New York that means NYSDOL-licensed abatement and, in the city, the right DEP filing before a permit is issued.
- Clear and document. Clearance air testing below 0.01 f/cc, then keep the report, the clearance result and the filings together. The next buyer, tenant or inspector will ask for them.
FAQs about asbestos test results
What does NAD mean on an asbestos report?
NAD means No Asbestos Detected. The laboratory found no asbestos above the detection limit in that specific sample. Some labs write NADIS, No Asbestos Detected In Sample. It applies to the sample, not to the building.
What does a positive asbestos test result mean?
It means the sample contained 1% or more asbestos, which classifies the material as asbestos-containing material under EPA rules and brings it into regulation.
Is 1% asbestos dangerous, and is 10% ten times worse?
No. The percentage sets the regulatory classification, not the risk. Risk comes from whether fibres can become airborne, which is a question of friability and condition. A crumbling 2% pipe insulation is a more urgent problem than an intact 15% floor tile that nobody is disturbing. Both are ACM and both are regulated identically once they pass 1%.
How long does it take to get asbestos test results?
Standard PLM analysis is usually a few business days, with rush turnaround available at a premium, and TEM takes longer. On most projects the laboratory is not the bottleneck: scheduling the inspector and sampling the full scope in one visit is.
How accurate is asbestos testing?
Accredited laboratory analysis is reliable within the limits of the method used. PLM is the EPA standard for bulk materials and is adequate for most samples, but it can under-report very low concentrations and struggles with certain matrices such as floor tile. Where a result is trace, close to 1%, or likely to be challenged, TEM gives the confidence PLM cannot. The larger source of error is usually sampling rather than analysis: too few samples, or a scope that missed materials the work will disturb.
What to do next
If you are holding a report you cannot read, the useful next step is to have someone qualified read it against your actual project: what was sampled, what was not, what the results classify, and what your permit or transaction will require. That is a different question from “is there asbestos”, and it is the one that decides cost and timeline.
UNYSE has tested New York buildings since 1993, and our inspectors hold the NYC DEP certification the city requires for permit filings. Send us the report and the scope of work, and we will tell you what it means and what has to happen next. You can also see how asbestos testing in New York City works end to end.
About the author
This article was written by Andrew J. McLellan, President and Founder of Environmental Education Associates, UNYSE’s sister company. He has overseen environmental safety training and consulting in New York since 1992, working alongside UNYSE’s team of 20 or more certified professionals. UNYSE Environmental Consultants has tested, guided and cleared New York buildings since 1993. Learn more about the UNYSE team here.
Sources: US EPA asbestos regulations and the 1% asbestos-containing material threshold; EPA method 600/R-93/116 for Polarized Light Microscopy analysis of bulk building materials; New York State Department of Labor asbestos licensing requirements; New York City Department of Environmental Protection asbestos filing requirements. Retrieved 11 September 2026. This article explains published requirements and is not legal advice. Confirm current rules with the relevant agency or your certified inspector before acting.
