Mold Assessment Best Practices

Overview

This lecture covers best practices and methods for mold assessment reports, focusing on sampling techniques, interpreting results, post-remediation verification, and common pitfalls in mold inspection and clearance.

Elevated or Not Elevated: Interpreting Mold Levels

• There are no federal or state numeric guidelines for "safe" or "elevated" indoor mold levels.
• Air contains a mix of mold spores (many species, some alive, some dead) both indoors and outdoors.
• Determining a mold problem relies on comparative data and professional judgment, not absolute numbers.

Air and Surface Sampling Methods

• Spore trap testing collects both live and dead mold spores from air for total spore counts.
• High-volume cassettes (15 lpm) are preferred over low-volume (5 lpm) for greater sampling accuracy.
• Surface sampling methods include swabs and slides but are not quantitative or reliable for exact contamination levels.
• More samples (at lower individual costs) are recommended to increase accuracy and reduce liability.
• Suggested protocol: at least one air sample per 1,000 sq ft, plus one outdoor control, and samples under cabinets.

Mold Types and Relevance

• Dry molds (e.g., Penicillium, Aspergillus) are common indoors and spread easily; wet molds (e.g., Stachybotrys) require major moisture.
• Outdoor spores found indoors usually indicate open windows, poor filtering, or dirty environments.

Advanced Testing: Culture and DNA/PCR

• Viable sampling (culture method) distinguishes live from dead spores and can pinpoint species, useful for insurance claims.
• DNA/PCR (ERMI/HERTSMI-2) detects mold species and fragments, but dust-based DNA tests often overestimate airborne exposure.
• Mold in dust = clean the dust; only airborne mold represents direct exposure risk.

Special Inspection Considerations

• Fresh paint, new carpet tack, or mismatched repairs may indicate hidden mold behind walls or baseboards.
• Air sampling inside walls is not recommended; focus on under cabinets for hidden mold.
• Particle counting under cabinets can help decide if air sampling is needed there.

Mold in HVAC Systems

• Mold in AC/ducting is a significant exposure source and often overlooked.
• Mold exposure requires a pathway (breathing spores), not just presence.
• Duct cleaning is often ineffective, especially with flex or fiberglass ducts.

Post Remediation Verification (PRV)

• IICRC S520 emphasizes visual inspection and air sampling inside containment, but sampling outside is critical to detect cross-contamination.
• PRV should include surface dust checks (wet Swiffer/white glove test).
• There are no official pass/fail numeric criteria; interpretation is based on comparative and scientific methods.
• Always explain PRV criteria and process clearly in reports.

Avoiding Pressure to Pass Bad Work

• Comparing only to outside air or using arbitrary thresholds is not defensible in legal proceedings.
• True clearance means both inside containment and adjacent areas are clean and not cross-contaminated.
• Use high-quality air filters (MERV 13+) during remediation and prior to clearance testing.

Key Terms & Definitions

• Spore Trap — Device collecting airborne mold spores for lab analysis (live and dead).
• Direct Microscopic Examination (DME) — Lab method for identifying/counting spores on slides.
• Viable Sampling — Culture-based method showing only living spores; identifies species.
• ERMI/HERTSMI-2 — DNA-based mold testing panels for environmental assessment.
• PRV (Post Remediation Verification) — Confirmation that remediation returned a site to normal fungal ecology.
• Containment — Sealed work area during mold remediation to prevent cross-contamination.

Action Items / Next Steps

• Review sampling protocols: number and placement of samples, and equipment used.
• Practice interpreting sample data without official numeric pass/fail criteria.
• Prepare clear, defensible criteria and explanations for PRV in your assessment reports.
• Ensure knowledge of state laws regarding mold assessment scope and limitations.
• Read IICRC S520 sections on PRV (12.2.12 and Ch.15) for full PRV requirements.