Asbestos Air Testing Lab Houston, TX — PCM by NIOSH 7400
Phase Contrast Microscopy fiber counting for OSHA personal exposure monitoring, area sampling and containment verification. Results reported in fibers per cubic centimeter and compared directly against the OSHA PEL of 0.1 f/cc. Analyzed in-house at 10200 East Freeway, Houston TX 77029 — samples received before 2:00 PM CST logged same day, same-day rush available.
Why accredited PCM monitoring protects your crew
OSHA Requires the Assessment
29 CFR 1926.1101 requires an initial exposure assessment for Class I–IV asbestos work, and 1910.1001 applies the same PEL to general industry maintenance. Without PCM data there is no assessment.
It Proves the Controls Work
Negative pressure enclosures, HEPA filtration and wet methods are only as good as the numbers behind them. Area samples inside and outside containment document that the engineering controls are actually holding.
Speed Is the Service
An exposure result a week late tells you what happened, not what to do. PCM is a fast analysis and we price same-day accordingly — the decision it informs is usually the next shift.
Know What It Does Not Say
PCM counts fibers by dimension, not by mineral. A high count in a fiberglass environment may contain no asbestos at all. We say so on the report rather than let the number imply more than it can carry.
OSHA Exposure Monitoring for All 50 States
Personal exposure monitoring is the most portable asbestos service we run, because the standard behind it is federal. The OSHA PEL is 0.1 f/cc in every state, and cassettes ship overnight from anywhere in the country.
The OSHA PEL Is Federal
29 CFR 1926.1101 and 1910.1001 apply nationally. The PEL and the excursion limit are identical in every state, so a personal exposure result means the same thing in Houston as in Ohio.
A Genuinely National Service
Because personal industrial-hygiene monitoring is federally regulated, states generally do not layer their own lab licensing onto it — New York's ELAP, for one, expressly does not certify laboratories for personal IH monitoring on that basis.
Accredited to ISO/IEC 17025
NIOSH 7400 fiber counting sits within our AIHA-LAP scope (LAP-101470) and our PJLA accreditation (137751). Both bodies are ILAC-MRA signatories.
Overnight From Anywhere
Free cassette kits with field blanks ship nationwide. Cassettes received before 2:00 PM CST are logged the same day, and PCM is fast enough that same-day results are genuinely available.
Area and clearance sampling are a different matter
Personal OSHA exposure monitoring travels well. Clearance does not. Several states require a laboratory to hold their own asbestos credential before analyzing area or clearance air samples originating there — including New York, Pennsylvania (and the City of Philadelphia separately), Massachusetts, Vermont, Connecticut, Rhode Island, Maine, Virginia, West Virginia, Hawaii and Louisiana — and some also require the person collecting the sample to be state-licensed. We hold the Texas DSHS license (#300529). If your samples are area or clearance rather than personal exposure, tell us the state first and see clearance testing.
What PCM Asbestos Air Testing Measures
PCM counts fibers collected on a filter from a known volume of air and reports a concentration in fibers per cubic centimeter (f/cc). It is the OSHA-referenced method for asbestos exposure monitoring, and it is the analysis you use when the question is not is there asbestos in this material but how much is in the air right now, and is anyone over the limit.
Air sampling is required whenever workers disturb asbestos-containing material — abatement, demolition, maintenance on thermal system insulation, gasket work, mechanical tear-off of asbestos-containing roofing. It runs alongside the containment: personal samples on the crew, area samples inside and outside the enclosure. To identify the material before work starts, see PLM bulk analysis.
- Personal exposure monitoring — breathing zone, task or full shift
- Area monitoring inside containment, at the negative-pressure exhaust and in adjacent occupied space
- Excursion sampling against the 30-minute 1.0 f/cc limit
- NIOSH 7400 A rules by default, B rules on request
- Analytical sensitivity stated on every report alongside the result
- Analyzed in-house by TX DSHS-licensed microscopists — no send-outs
Who does what
AGT Labs is an analytical laboratory. Your EHS team, your consultant or your abatement contractor runs the pumps and collects the cassettes; we analyze them. We do not visit sites or perform field sampling. We supply the media, the protocol and the accredited analysis.
What PCM Cannot Tell You
Most laboratories leave this out. It matters enough to your data interpretation that we put it on the page.
PCM counts fibers. It does not identify them.
Under phase contrast, an asbestos fiber, a fiberglass fiber and a cellulose fiber of similar dimensions all count identically. The method counts anything longer than 5 µm with an aspect ratio of 3:1 or greater, regardless of what it is made of.
High-background environments
Insulation work, fiberglass handling, fresh drywall dust and mineral wool all generate countable fibers. In those settings a PCM result can read high with no asbestos present at all. Interpret the number against what else is airborne on that job.
Why PCM is still the right method
The OSHA PEL is itself written in PCM fiber counts. Substituting a more specific method does not produce a number comparable to the limit. For compliance monitoring, PCM by NIOSH 7400 is both the correct and the legally referenced analysis.
When you need TEM
Transmission electron microscopy resolves fiber identity and detects fibers below the PCM size range. AGT Labs does not hold TEM scope. If your project or specification requires TEM, call us — we will say so plainly rather than substitute PCM.
NIOSH 7400 — A Rules and B Rules
NIOSH 7400 defines two counting conventions, and which one your report uses changes the number. Specify it on the chain of custody — it cannot be applied retrospectively after the count.
| Convention | Counting criteria | Used for | Default? |
|---|---|---|---|
| A rules | All fibers longer than 5 µm with aspect ratio ≥ 3:1 | OSHA compliance monitoring — the convention the PEL is written against | Yes |
| B rules | Narrower criteria with restricted fiber dimensions | Specific research and inter-method comparison applications | On request |
Default behavior
Unless you specify otherwise on the COC, we count by A rules and state the convention on the report alongside the result and the analytical sensitivity achieved. If your project protocol requires B rules, mark it clearly on the chain of custody before shipping.
PCM Sampling Media, Flow Rates & Volumes
Get these right and every sample produces a countable filter. Get the volume wrong and the sample is lost. Step-by-step in the field: how to collect asbestos air samples for PCM.
OSHA PEL & Excursion Limit — Comparing Your Result
Both the construction standard and the general industry standard carry the same limits, and both require an initial exposure assessment.
| Limit | Value | Averaging period | Citation |
|---|---|---|---|
| Permissible Exposure Limit (PEL) | 0.1 f/cc | 8-hour TWA | 29 CFR 1926.1101 · 1910.1001 |
| Excursion Limit (EL) | 1.0 f/cc | 30 minutes | 29 CFR 1926.1101 · 1910.1001 |
How the comparison is reported
Every report states the fiber concentration, the volume sampled, the analytical sensitivity achieved and a direct comparison against the PEL. Where the sample period is shorter than the shift, the report gives the concentration for the period sampled — the 8-hour TWA calculation depends on the rest of the shift, which is yours to apply.
Personal vs Area PCM Monitoring
Different questions, different placement, different evidentiary weight. On an active abatement you run both.
Personal Monitoring
Pump on the worker, cassette in the breathing zone, run for the task or the shift. This is what OSHA compliance is judged on, and the only sample type that documents an individual's exposure. Required for the initial exposure assessment.
Area Monitoring
Fixed-location samples. Inside containment they show whether engineering controls are holding; outside containment and at the perimeter they document that adjacent occupied areas were not affected. Area results do not substitute for personal samples in a compliance record.
Clearance Sampling
After the work, against a different criterion and a different protocol — aggressive sampling, higher volumes, a written pass/fail determination. It is PCM analysis, but a different service with its own requirements.
Which PCM sample type does your job need?
Every PCM Analysis, Every Standard, Every Deliverable
What each PCM sample type returns, side by side.
| Analysis Type | Method / Standard | Sample Media | Report Deliverable | Rush? |
|---|---|---|---|---|
| PCM Personal Air Monitoring | NIOSH 7400 (A & B rules) | 25 mm MCE cassette (0.8 µm) | f/cc + OSHA PEL comparison + analytical sensitivity | Yes |
| PCM Area Air Monitoring | NIOSH 7400 (A & B rules) | 25 mm MCE cassette (0.8 µm) | f/cc by location + containment comparison | Yes |
| PCM Excursion Sampling | NIOSH 7400 · 30-minute period | 25 mm MCE cassette (0.8 µm) | f/cc + 1.0 f/cc excursion limit comparison | Yes |
| PCM Field Blanks | NIOSH 7400 QA requirement | 25 mm MCE cassette (0.8 µm) | Blank count, reported with the batch | Yes |
What is on every report
Method reference and counting convention, fiber concentration in f/cc, volume sampled, analytical sensitivity achieved, direct PEL comparison, analyst signature, QA/QC sign-off, and the accreditation numbers the result rests on. Delivered through a secure portal and accepted by OSHA, TX DSHS and PJLA-accredited programs.
PCM Turnaround Times & Free Cassette Kits
PCM is a fast analysis and same-day is genuinely available — most exposure decisions cannot wait a week.
Free PCM Air Sampling Kit Includes
- 25 mm MCE cassettes, 0.8 µm, with 50 mm conductive cowls
- Field blank cassettes to meet the 10% QA requirement
- Lot-certified, calibration-traceable media documentation
- Pre-numbered Asbestos Chain of Custody form
- Flow rate and volume reference card
- Pre-paid UPS return shipping label (domestic)
Kits ship via UPS Ground — order with 5 business days notice. Houston metro courier pickup available: (713) 453-6090.
From Cassette to Certified PCM Report
Request Kit or COC
Free PCM kits ship with 5 business days notice, or use your own lot-certified MCE cassettes.
Calibrate & Sample
Calibrate the pump, record the flow rate, sample to volume. Watch the filter loading in dusty work.
Blanks & COC
Open your field blanks 30 seconds, seal, label as blanks. Record flow, start and stop times per cassette.
Ship Same Day
Caps on, upright, tamper-evident outer bag. Received before 2:00 PM CST logs the same day.
Counted & Reported
Counted by TX DSHS-licensed microscopists in Houston, QA reviewed, delivered with the PEL comparison.
Who runs the pumps
You, your consultant or your abatement contractor. AGT Labs does not visit sites or perform field sampling. We supply the media, the flow-rate and volume protocol, and the accredited analysis — the sampling plan and the pumps are yours.
PCM Asbestos Air Testing — Frequently Asked Questions
Answered by the accredited microscopists who run the counts.
What is PCM asbestos air testing?
Does a PCM result prove the fibers were asbestos?
What is the difference between NIOSH 7400 A rules and B rules?
What is the OSHA PEL for asbestos?
What volume should I sample for PCM?
What flow rate should I use?
Can I use my own cassettes?
How many field blanks do I need?
Is PCM accredited at AGT Labs?
Do I need PCM or PLM?
How fast can I get PCM results?
Who collects the air samples?
Need PCM Air Samples Counted?
AIHA-LAP LAP-101470, PJLA 137751 and TX DSHS #300529. Free cassette kits, same-day rush, results compared directly against the OSHA PEL.