How to Read an Air Sample Moldlab Report

Air sample reports can be highly useful for mold inspectors, but only when the numbers are interpreted in context. A spore trap air sample is a snapshot of the air at the time of collection, not a complete picture of every condition in a building. That is why the report should be read as one part of the overall inspection, alongside the visual assessment, moisture findings, building history, and any outdoor or reference comparison sample.

This guide explains the main sections and terms on a Moldlab air sample report so inspectors can read results more confidently and communicate clearer, client-ready conclusions.

For inspectors, reading an air sample report well is just as important as receiving it quickly. Clear interpretation helps support better client communication, stronger recommendations, and more confident next steps.

What sections are included in the report?

A typical Moldlab air sample report includes:

• Chain of Custody
• Report
• Frequently Asked Questions (optional)
• Glossary (optional)

The Chain of Custody documents what was submitted and helps preserve sample tracking. The report contains the analytical results. The FAQ and glossary help explain key terms for interpretation and client communication.

If you are submitting samples for analysis, here is how to fill out a chain of custody form correctly so the report can be processed without avoidable delays.

Start with the big picture: are the results “normal”?

A practical general guideline is that the concentration and types of spores in the indoor sample should be similar to or lower than those in the outdoor baseline or reference sample. When indoor counts are materially higher than the outside sample, or when certain water-damage-associated spore types are elevated indoors, that can support further investigation.

That said, inspectors should be careful not to overstate what an air sample can prove.

Important interpretation notes

• Air sampling is often best used as an alert tool for problems that may not be obvious during the visual inspection.
• Airborne mold concentrations can vary significantly over time.
• True exposure assessment usually requires multiple samples taken at different times and may involve more advanced statistical analysis.
• Some groups on the report, such as Aspergillus / Penicillium, contain morphologically similar spores that cannot always be differentiated by this method alone.
• A culture sample may be needed if more specific differentiation is required.

What does “Calculated Concentration” mean?

The Calculated Concentration is the estimated concentration of spores in the air, usually reported as spores per cubic meter of air. For a quick point of reference, a cubic meter of air is approximately the size of a refrigerator.

This number is useful because it allows inspectors to compare samples and understand how many spores are estimated to be present in a given air volume. It is derived from:

• the pump flow rate,
• the pump run time,
• the proportion of the sample analyzed, and
• the raw count observed by the analyst.

In practical terms, the calculated concentration helps normalize the result so samples can be compared more meaningfully across different sampling conditions.

Why inspectors use it

Calculated concentration is especially helpful for:

• comparing indoor and outdoor samples,
• comparing multiple rooms,
• evaluating whether one area appears more impacted than another,
• and understanding the scale of airborne spores rather than relying only on the raw count.

Because it is a calculated value, it is typically rounded to two significant figures.

What is the “Raw Count”?

The Raw Count is the number of spores the analyst actually observed on the slide while viewing the sample under the microscope.

Moldlab uses this observed count to generate the calculated concentration. If the count exceeds the lab’s counting threshold, the report may show the result as greater than 100 rather than a more exact number.

Why this matters

The raw count is part of the foundation of the result, but inspectors usually should not rely on raw count alone when explaining findings to clients. The calculated concentration is generally more useful for comparing samples because it accounts for sample volume and analytical factors.

What kind of sample is this?

An airborne mold spore sample is a non-cultured air sample. Air is pumped through a spore trap, and particles from the air collect on the sample surface. The analysis reports both live and dead spores, as well as other particles that may be present in the sample.

If you need a deeper overview of sample handling, reporting context, and turnaround, see our page on accredited air sample and mold spore count analysis for inspectors and consultants.

This is why the report should be described as a snapshot rather than a complete long-term measurement of indoor conditions.

What is the “Debris Field Rating”?

The Debris Field Rating is the analyst’s visual estimate of how much non-fungal particulate matter is present on the sample.

That may include things like:

• fibers,
• dust and debris,
• pollen,
• insect fragments,
• skin cells,
• and other particulate matter.

Common ratings include:

• None Detected
• Trace
• Minor
• Moderate
• Heavy
• Occluded

Why debris matters

The higher the debris load, the harder it can be for the analyst to clearly see and count spores. In dusty or heavily contaminated environments, especially crawlspaces, wall cavities, or active construction areas, excess debris can reduce visibility and introduce negative bias into the result.

That means a sample with a heavy or occluded debris field may underrepresent what is actually present in the air. If you want a deeper breakdown of how debris affects interpretation, see our guide to why debris field ratings matter on spore trap reports.

What are “Significant Figures” on the report?

Significant figures show the degree of precision used when reporting calculated values.

On a Moldlab air sample report, calculated numbers such as the calculated concentration and minimum reporting limit are rounded to two significant figures. Values that were not calculated are not rounded the same way.

This is useful because it keeps the reported numbers consistent with the practical accuracy of the method and avoids creating a false sense of precision.

Inspector takeaway

When explaining a result, it is better to focus on the overall pattern and the comparison between samples than to over-interpret tiny numeric differences.

What is the “Minimum Reporting Limit”?

The Minimum Reporting Limit is the lowest calculated concentration that can be reported for a spore type if spores are detected.

In practical terms, it reflects the smallest step in concentration represented by the analytical setup. It is based on:

• the portion of the sample analyzed,
• the pump flow rate,
• and the pump run time.

This matters because if a spore type is listed with a raw count of zero, that does not necessarily mean the true airborne concentration is absolutely zero. It means the sample did not detect that spore type within the limits of the method.

Important caution

The minimum reporting limit is a helpful guide to detectability, but it does not account for negative bias caused by a difficult debris field.

Common interpretation mistakes to avoid

1. Treating the sample as a complete building diagnosis

An air sample is one data point collected at one point in time. It should support, not replace, the rest of the inspection.

2. Looking only at total numbers

Spore types, indoor-outdoor comparison, moisture evidence, and room conditions all matter.

3. Ignoring debris field limitations

A dusty or occluded sample can make the result look lower than actual conditions may justify.

4. Overstating “none detected”

A non-detect is not the same as proving absence under all conditions.

5. Over-interpreting small differences

Because calculated values are rounded and sampling has natural variability, small numeric gaps are not always meaningful by themselves.

How to explain results to clients more clearly

When walking a client through an air sample report, it often helps to use plain language such as:

• What was sampled: indoor air, outdoor reference, or both
• What was found: the main spore groups and whether they were low, similar, or elevated compared with the reference sample
• What the result suggests: whether the air sample supports concern about an indoor mold source
• What the limitations are: this was a snapshot, and additional inspection context still matters
• What the next step is: further moisture investigation, additional sampling, remediation planning, or no additional action based on the overall inspection findings

In North Texas projects, inspectors may also want additional outdoor comparison context from Moldlab’s DFW Outdoor Flashback Report.

A practical framework for inspectors

When reviewing a Moldlab air report, work through these questions in order:

1. Was the sample type and location appropriate?
2. Is there an outdoor or reference comparison?
3. Are indoor spore types and concentrations similar to or lower than the reference sample?
4. Are water-damage-associated spores elevated indoors?
5. Does the debris field limit confidence in the result?
6. Do the report findings fit the visual and moisture evidence from the inspection?
7. What is the clearest client-ready conclusion based on the full picture?

Final thoughts

A strong air sample interpretation does not come from reading one number in isolation. It comes from understanding what the report measures, where the method has limits, and how the findings fit with the rest of the inspection.

For inspectors, the most useful air sample reports are not only accurate. They are also clear enough to support confident explanations, practical decisions, and client communication.

If you want a broader overview of Moldlab’s accredited air sample and mold spore count analysis, start there. If you are ready to submit samples, use our how to send us samples walkthrough for forms, sample details, and submission steps.