Mold Testing Methods

There’s a ton of confusion online about how to properly test for mold — especially when it comes to deciding whether you need air sampling, swabs, tape, ERMI, or dust tests.

Each mold testing method serves its own purpose, depending on what you’re trying to find out.

As a licensed mold inspector, I use a variety of sampling techniques tailored to each situation. This guide will help you understand the different mold testing methods available — and which one makes the most sense for your home.

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🧪 Common Mold Testing Methods

Air Sampling

This is the most common professional method for detecting airborne mold spores. A pump draws air through a cassette, capturing spores on a slide. Indoor and outdoor samples are compared to detect elevated mold levels indoors.

ERMI Mold Testing

ERMI (Environmental Relative Moldiness Index) is a DNA-based dust test. It detects 36 specific mold species from collected dust using advanced molecular analysis. Best used for long-term exposure analysis.

Tape Sampling

A piece of clear adhesive is pressed against visible mold growth. The sample is mounted to a slide and examined under a microscope to determine species and spore concentration. A great method for surface-level mold confirmation.

Dust Sampling

Dust samples are collected from surfaces like floors, furniture, or HVAC filters. These are analyzed for mold presence — often used when investigating past mold exposure or chronic illness symptoms.

Bulk Sampling

A physical piece of material (e.g., drywall, carpet, insulation) is removed and sent to a lab to determine how deeply it’s contaminated with mold. Ideal for confirming whether materials need full removal or cleaning.

Swab Sampling

Swab testing is a type of surface sampling that uses a sterile cotton swab over a 1-inch area. Results include both species identification and spore concentration. It’s commonly used in bathrooms, kitchens, and on furniture.

Wall Cavity Sampling

This method uses an air sampling tube placed inside wall cavities through outlets or small drill holes. It's critical for identifying hidden mold growth not visible on surfaces.

Pat Sampling (Disturbance Testing)

This involves using air sampling while actively disturbing a material, like stomping on carpet or banging on drywall. It helps assess how easily spores become airborne in the living environment.

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🏠 At-Home Mold Testing Options

My Mold Detective Review

Learn how this at-home mold test kit compares to professional air testing — and when it might make sense to use.

What Does Mold Smell Like?

Mold often gives off a musty, earthy odor before it becomes visible. Learn how to recognize mold smell and confirm your suspicions.