Why ERMI Results Can Look Different Between Rooms (And Why That Didn’t Mean Something Was Wrong)

Variation doesn’t automatically equal danger — it often reflects how dust behaves in different spaces.

When I first compared ERMI results from different rooms, I felt a jolt of worry.

The numbers weren’t consistent. Some rooms looked “worse” than others.

It was easy to interpret that as a sign that something had gone wrong in specific areas.

I assumed uniformity was the baseline — and anything else meant a problem.

This didn’t mean ERMI was flawed — it meant I hadn’t yet understood how variation naturally occurs.

Why I Expected ERMI Numbers to Be the Same Everywhere

In my mind, the house was one system, and ERMI was a mirror of that system.

Any difference felt like a hidden failure I needed to investigate.

I thought every number should tell the same story.

This expectation made the results feel confusing instead of informative.

ERMI measures settled dust, which accumulates differently in each space.

Factors like airflow, sunlight, humidity, furniture placement, and cleaning patterns all influence results.

Differences between rooms often reflect environment, not new contamination.

Understanding what an ERMI test actually measures helped me stop interpreting variation as a problem.

I wanted a single answer about the safety of the house.

Seeing differences made it harder to feel confident in any interpretation.

Multiple numbers felt like multiple warnings.

This mirrored what I experienced when ERMI didn’t align with how my body felt in the house.

Once I realized dust and mold spores settle differently across rooms, the differences felt expected.

Variation became part of the context instead of a sign of failure.

Inconsistency didn’t mean danger — it meant complexity.

This helped me hold the results without overreacting to individual numbers.

Instead of looking for a “worst” room, I focused on patterns over time.

This allowed ERMI to function as a baseline, not a verdict, which reduced unnecessary stress.

Patterns mattered more than any single reading.

Is it normal for ERMI results to differ between rooms?
Yes. Dust accumulation varies naturally, so differences are expected.

Does variation mean the house has multiple problems?
Not necessarily. It often reflects how environmental factors influence settled dust.