An environmental laboratory report can look intimidating: tables of numbers, abbreviations and units that are rarely explained. Yet the report is the evidence behind every conclusion an inspector draws. Knowing a few basics makes it far easier to understand what your results actually say.
Start with the sample information
Every report should identify each sample: where it was taken, when, by what method and, for air samples, how much air was collected. A sample result means little without knowing where it came from. The report should also reference the chain-of-custody record showing how the sample traveled from the property to the laboratory.
Mold air sampling reports
- Concentration. Results are usually reported as spores per cubic meter of air (spores/m³), often broken down by spore type.
- The outdoor reference. Indoor results are interpreted by comparison with an outdoor sample taken at the same time. Indoor levels notably higher than outdoors, or a different mix of spore types, can suggest an indoor source.
- Detection limits. “ND” means not detected above the method’s detection limit — not necessarily zero.
There are no federal regulatory limits for indoor mold spore levels, so results are interpreted in context rather than against a single pass/fail number.
Asbestos bulk sample reports
Asbestos results are typically reported as the type of asbestos found (such as chrysotile) and its estimated percentage in the material. Under the U.S. EPA definition, a material with more than 1% asbestos is considered asbestos-containing. “None detected” applies only to the specific material sampled.
Lead reports
- Paint (XRF or paint chip). XRF readings are reported in milligrams per square centimeter (mg/cm²); paint-chip results may be reported by weight. Under the federal definition, paint at or above 1.0 mg/cm² or 0.5% by weight is lead-based paint.
- Dust wipes. Reported in micrograms per square foot (µg/ft²) and compared with the applicable federal or state standard for floors, window sills and troughs.
- Drinking water. Reported in micrograms per liter, equivalent to parts per billion (ppb), and compared with the applicable EPA action level. First-draw and flushed samples together help show whether the lead is coming from plumbing close to the tap.
Questions worth asking
- What was each sample compared against, and why?
- Do the results agree with what was observed on site?
- What do the results not tell us?
- Is any follow-up testing actually needed, or would it add little?
A number on its own is not a conclusion. Results become meaningful only alongside where the sample came from and what was seen on site.
A good inspection report translates the laboratory data into plain language. If you only receive a conclusion, ask for the laboratory report itself; you are entitled to see the evidence.