As the scientific community continues to grapple with the complexities of indoor mold, the GO AQS Mold Working Group conducted a comprehensive survey of industry experts. The goal was to move past anecdotal evidence and establish a clearer picture of how mold should be measured, interpreted, and communicated to the public.

1. International and Regional Guidelines

The Question: Which existing guidelines (WHO, AIHA, Health Canada, etc.) do you currently utilize as a reference point?

Conclusion: There is no single global authority used by all. While the WHO and Health Canada are the most frequently cited for their qualitative approach (emphasizing moisture control), practitioners in specific regions (like Italy or Spain) often look to local standards (e.g., UNE or INAIL) that provide numerical suggestions. The collective agreement is that current guidelines are useful for framework, but insufficient for universal safety limits.

2. Assessment Logic: Comparative vs. Absolute

The Question: Do you use comparative logic (Indoor vs. Outdoor) or absolute numerical limits?

Conclusion: There is a strong consensus (over 80%) favoring comparative logic. Experts overwhelmingly agree that an indoor environment must be judged against its immediate outdoor surroundings. Absolute numerical limits are viewed with skepticism because “background” mold levels vary wildly by geography and season.

3. The “Gold Standard” for Health Links

The Question: What specific peer-reviewed studies do you consider the “gold standard” for linking mold to health effects?

Conclusion: There is significant disagreement or a perceived “gap” here. While some experts point to specific epidemiological reviews (e.g., Jiménez-Uribe et al., 2026), many others noted that the “gold standard” doesn’t truly exist yet. The consensus is that while the correlation between dampness and health is clear, the causation linked to specific spore counts remains elusive.

4. Dose-Response Relationships

The Question: Have you identified a specific dose-response relationship for species like Stachybotrys or Aspergillus?

Conclusion: The collective answer is a resounding “No.” Experts agree that because mold health effects are often allergic or toxigenic in nature, the response is highly dependent on the individual’s immune system rather than a linear “dose” of spores.

Just like some people are born with or develop peanut allergies while others don’t, some individuals have immune systems that are highly sensitized to specific mold species like Aspergillus or Penicillium. For them, a “low” spore count is still a health crisis.

5. Vulnerable Populations

The Question: Are there specific populations (immunocompromised, infants, elderly) that require distinct protective thresholds?

Conclusion: Unanimous agreement. Experts concur that “one size does not fit all.” Even if a universal limit were established for healthy adults, it would be inadequate for high-risk groups. This further complicates the push for a single numerical “safe” limit.

6. Gaps in the Literature

The Question: What gaps prevent the establishment of a universal “safe” limit?

Conclusion: The group identified methodological inconsistency as the biggest hurdle. From different sampling devices to various culture media and a lack of human dose-response curves, the data is currently too “noisy” to support a global standard.

7. Preferred Sampling Methods

The Question: What is your preferred method for sample collection?

Conclusion: Spore traps remain the most common tool, but there is an emerging call for a multi-modal approach. Experts suggested that air sampling should be supplemented with bulk sampling, dust analysis (ERMI/MSQPCR), and even real-time metabolite sensing to get a full picture.

8. Recommendation: Numerical Limit vs. Trigger Level

The Question: Should GO AQS recommend a specific numerical limit or a “trigger level”?

Conclusion: The group strongly favors a “Trigger Level” model. A trigger level mandates further investigation (checking for leaks, odors, or visible growth) rather than providing a simple “pass/fail” number that might give a false sense of security.

9. Building Type Adjustments

The Question: How should protective limits be adjusted for different building types (Hospitals vs. Schools vs. Residential)?

Conclusion: Experts agree that sensitivity must scale with the building’s purpose. Hospitals require the most stringent “near-zero” thresholds, while residential and school environments allow for slightly higher baselines, provided no active growth is present.

10. Environmental Triggers

The Question: What environmental triggers should be monitored alongside spore counts?

Conclusion: Relative Humidity (RH) and Surface Moisture are the top priorities. Most experts identified RH >60% as the primary “red flag” that should be monitored in real-time to prevent mold before it starts.

11. The Most Important Safety Message

The Question: What is the single most important factor GO AQS should communicate to the public regarding mold safety?

Conclusion: The group reached a powerful consensus: Mold is a moisture problem. The single most important message is that sampling is secondary to fixing the water source. As one expert summarized: “If moisture is controlled, the risk is controlled.”

Next Steps

We are moving directly into the next phase of our mission. Here is what you can expect in the coming weeks:

• Literature Meta-Analysis: Following the suggestions of several members, we are beginning a focused review of the scientific literature and DOI links provided to identify the most robust evidence for health-based “trigger levels.”
• Expert Consensus Call: We will be arranging a group call to discuss these survey findings in detail and begin drafting a formal recommendation.

Thank you for your dedication to improving indoor air quality and public health. We look forward to our continued collaboration.