Short answer
Check four things: where each sample was taken, which method was used (screen or NIOSH 9111 laboratory wipe), the result for each sample against 0.5 µg/100cm², and whether a blank was included. A report that can’t tell you which surface each result came from is hard to act on.
The parts of a report
| Section | What to look for |
|---|---|
| Property details | Address, date, who sampled, who commissioned the test |
| Method | Presumptive screen, or NIOSH 9111 laboratory wipe |
| Sample table | Sample ID, room, surface, area sampled, result |
| Guideline | The figure results are compared with — 0.5 µg/100cm² residential |
| Blank | Result for the unused wipe |
| Laboratory certificate | Attached unaltered, from an accredited laboratory |
| Summary | Plain-English explanation of what the results mean |
Reading results
- Below LOR — below the laboratory’s limit of reporting.
- Below 0.5 µg/100cm² — under the residential figure.
- 0.5 µg/100cm² or above — over the residential figure; that surface needs attention.
Roof spaces and commercial areas are compared with 10 µg/100cm² under the Environmental Health Australia code, so check which figure has been applied to each sample.
Discrete versus composite results
A discrete result applies to one surface. A composite combines several wipes, so the result is spread across them and a single high surface may not stand out. If a composite is near the guideline, discrete re-sampling of the contributing locations shows where the residue is.
Questions to ask
- Were all rooms sampled, including every room a child under 16 uses?
- Were exhaust fans, return-air vents and rarely repainted surfaces included?
- Are porous surfaces (unsealed timber, raw plaster, carpet) noted, since wipes can understate them?
- Was the sampler independent of anyone doing works on the property?
Questions
What does ‘less than LOR’ mean on a meth report?
The result was below the laboratory’s limit of reporting — the smallest amount it reports with confidence. It is a low result, not a measured zero.
Why is there a blank sample on my report?
A blank is an unused wipe handled like the others. A blank with no detectable residue shows the sampling media was not contaminated. The code of practice expects at least one per property.
One room is over 0.5 and the rest are under. Is the house contaminated?
That room is. Whether the rest needs attention depends on how many locations were sampled and what the property is being used for. Discuss the next step before deciding.
Sources
- Australian Voluntary Code of Practice: Assessment, remediation and validation — former clandestine drug laboratories and other methamphetamine contaminated properties (2019) — Environmental Health Australia
- Clandestine Drug Laboratory Remediation Guidelines (2011) — Australian Government — Attorney-General’s Department / Australian Crime Commission
Facts on this page checked against these sources on 29 October 2026.