Short answer: Clearance testing is the check that happens after abatement, before anyone takes the containment down. A qualified person inspects the area visually and, on higher-risk scopes, air samples are drawn and analyzed, then written confirmation is issued. We do this independently, because we never perform abatement ourselves.
What Actually Ends an Abatement Job?
Written confirmation from a qualified person, after a final inspection, that the hazardous material was safely contained or removed. Where air sampling was part of the scope, the air results are included in that confirmation.
Abatement ends with a bag count and a broom-clean floor. What it should end with is evidence. On higher-risk scopes that evidence is measured air samples, analyzed at an accredited laboratory, confirming fibre levels in the work area are below acceptable limits before anyone removes the containment and moves back in.
We act strictly as independent testers. We don't perform abatement, we aren't affiliated with abatement contractors, and our only deliverable is the truth about your air. That independence is precisely what makes our clearance letters useful: to municipalities releasing demolition permits, to project managers signing off on re-occupancy, and to homeowners who want to sleep well after a stressful removal.
When Do You Need Air Testing?
Five situations account for nearly every call we take. Post-abatement clearance is the most common, but air sampling also earns its keep while work is underway and after an accidental disturbance.
- Post-abatement clearance: the final check before containment comes down and the space is re-occupied
- During abatement: monitoring outside containment to verify the enclosure is holding
- Occupied buildings with known asbestos: reassurance sampling in homes, offices and stratas managing asbestos in place
- After a suspected disturbance: a contractor cut into the wrong ceiling, a DIY project went sideways, storm or fire damage exposed old materials
- Renovation hand-back: proving to returning trades that the site is safe
How Does Air Clearance Testing Work?
Pumps, a visual inspection, lab analysis, then a letter. Most clearances finish within one business day of the abatement contractor packing up.
- Placement. Calibrated sampling pumps are positioned in and around the work area, drawing a measured air volume through filter cassettes.
- Visual inspection. For clearances, sampling is paired with a close visual inspection of the abated area. Dust and debris fail the space before the lab does.
- Accredited analysis. Filters are analyzed by PCM, with TEM available where regulation or peace of mind demands specific fibre identification.
- Clearance letter. You receive the air results and a written clearance suitable for permits, project files, insurers and tenants.
PCM or TEM: Which Air Analysis Do You Need?
PCM is the routine method for clearance; TEM is used when the fibres themselves have to be identified. Most residential clearances run on PCM.
| PCM (phase contrast microscopy) | TEM (transmission electron microscopy) | |
|---|---|---|
| What it counts | All fibres above a size threshold, without identifying them | Fibres identified specifically, including very fine ones |
| Typical use | Routine clearance and monitoring during abatement | Disputes, sensitive occupancies, regulatory requirement |
| Turnaround | Fastest, often same day | Longer, and more expensive |
We tell you which method your scope calls for before sampling, and quote it that way. If you are not sure whether your project needs clearance at all, the pre-demolition survey or pre-renovation survey report will say so.
Air Monitoring & Clearance FAQs
Why shouldn’t the abatement contractor do their own clearance testing?
Because they’d be grading their own homework. Independent clearance testing means the party confirming the air is clean has no financial stake in the abatement being declared finished. Many municipalities, project managers and informed homeowners insist on third-party clearance for exactly this reason.
What is a clearance letter?
A written confirmation from a qualified person that the work area has been inspected following abatement and that the hazardous material was safely contained or removed. Where air sampling was part of the scope, the air results are included. It is the document that lets your renovation crew return, your demolition permit proceed, or your tenants move back in.
How is the air actually tested?
Calibrated pumps draw a measured volume of air through filter cassettes placed in the work area. Filters are analyzed by phase contrast microscopy (PCM) for fibre concentrations, with transmission electron microscopy (TEM) available when fibre identification is required.
How long does clearance take?
Air sampling itself runs a few hours depending on the required air volume. Combined with lab analysis, most clearances complete within one business day of the abatement contractor finishing, and rush results can compress that further.