Professional Indoor Air Quality Testing

Key Differentiators: A Side-by-Side Comparison

Feature

Dust Characterization

ERMI (Environmental Relative Moldiness Index)

Primary Purpose

To identify all types of unknown particles in dust to pinpoint sources of contamination and allergens.

To assess the historical presence of mold and determine the likelihood of a water-damaged building.

What it Analyzes

Nearly all particles in a dust sample, including biological and inorganic materials.

The DNA of 36 specific mold species.

Methodology

Polarized Light Microscopy (PLM), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and X-Ray Diffraction (XRD).

Mold Specific Quantitative Polymerase Chain Reaction (MSQPCR), a DNA-based method.

Result

A detailed report itemizing the various components found in the dust.

A single numerical score (ERMI score) that compares the home's mold levels to a national average.

Scope

Broad and comprehensive, identifying a wide range of non-mold contaminants.

Focused exclusively on a specific set of mold species.

Application

Ideal for initial site surveys when the cause of poor air quality is unknown, as it can identify a wide range of issues.

Primarily a research tool used to provide a long-term "history" of mold exposure, especially in cases of suspected water damage.

Dust characterization is a key component of indoor air quality analysis, focusing on identifying the composition of dust to determine potential sources of pollutants and allergens. This process goes beyond simple particle counting, using advanced analytical methods to break down the makeup of the dust.

Dust Characterization incorporates physical testing with various microscopy and diffraction techniques. These include:

• Polarized Light Microscopy (PLM): To identify materials by how they interact with polarized light.

• Scanning Electron Microscopy (SEM): To provide high-resolution images of the dust particles.

• Transmission Electron Microscopy (TEM): To analyze the internal structure and composition of particles.

• X-Ray Diffraction (XRD): To identify crystalline substances within the dust.

These methods can identify a wide range of unknown particles, from common materials like cotton fibers, dander, and dust mites to less common ones like carbon black, metal oxides, and minerals.

For this analysis, air sampling is typically performed using a 0.1m Polycarbonate filter and an Air Analysis Cassette. The Air Analysis Cassette is used with a flow rate of 10-15 lpm (liters per minute) for a sample volume of 75–200 liters. This analysis is often used with Air Analysis Cassettes to identify any fungal allergens, making it an ideal procedure for initial site surveys when indoor air quality is in question.

In addition to dust characterization, a thorough inspection for mold includes looking for sources of mold and the conditions required for its growth. Instruments such as a thermohygrometer, laser particle counter, infrared camera, and moisture meter are used. Testing includes air and surface samples, as well as enzyme detection (ATP) via a luminometer.

The typical services and turnaround times for these analyses are:

• Base fee for inspection

• Air and surface lab fees (24-hour TAT)

• ATP swabs

• Dust Characterization Analysis

Situation: A homeowner or building manager notices a persistent musty smell, or occupants are experiencing unexplained respiratory issues, allergies, or other health symptoms while inside. They suspect that poor indoor air quality due to mold or other airborne particles may be the cause.

Solution: An indoor air quality analysis service is deployed to investigate the issue. The service includes:

• Initial Inspection: A thorough physical inspection is conducted to identify potential sources of mold and conditions conducive to its growth, using instruments like a thermohygrometer, infrared camera, and moisture meter.

• Comprehensive Testing:

• Air and Surface Sampling: Samples are collected and tested for mold and other allergens.

• Dust Characterization: Dust samples are taken and analyzed using advanced techniques like PLM, SEM, and TEM to identify the exact composition of all particulate matter, including common allergens and unusual materials.

• Enzyme Detection (ATP): Swabs are used to detect biological residue that may indicate mold growth.

• Detailed Reporting: The analysis provides a clear report on the presence and type of contaminants, allowing the client to take targeted action to remediate the problem and improve indoor air quality.

To clearly differentiate between Dust Characterization and ERMI, it is essential to understand the distinct purpose and methodology of each service. While both analyze dust, their goals and the information they provide are fundamentally different.

What is ERMI?

The Environmental Relative Moldiness Index (ERMI) is a DNA-based dust analysis developed by the U.S. Environmental Protection Agency (EPA). Its primary purpose is to provide a standardized, objective tool for researchers to compare the relative "moldiness" of a home to a national database. ERMI is used for dust analysis in dust characterization and only this situation. AEC does not recommend ERMI any other reasons that dust characterization. Indoor air quality to measure for mold spore types and concentrations, we recommend using spore trap air analysis.

• Methodology: The ERMI test uses a technique called Mold Specific Quantitative Polymerase Chain Reaction (MSQPCR) to analyze a dust sample, typically collected by vacuuming carpeted areas. The test specifically identifies and quantifies the DNA of 36 different mold species, categorized into two groups: those commonly found in water-damaged buildings and those typically found in outdoor environments.

• What it reveals: The analysis generates a single numerical score, the "ERMI score," which reflects the likelihood that a home has a history of water damage and related mold growth. This test provides a historical snapshot of mold presence, as settled dust can accumulate mold spores over months or years.

What is Dust Characterization?

Dust Characterization is a broader, more comprehensive analysis of all particulate matter within a dust sample, not just mold. Its purpose is to identify the sources of a wide range of unknown particles, providing a more complete picture of the indoor environment.

• Methodology: This analysis uses physical testing methods like Polarized Light Microscopy (PLM), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). These techniques are used to visually and chemically identify the individual components of the dust.

• What it reveals: Dust characterization can identify nearly all unknown particles, from biological materials like cotton fibers, pet dander, and dust mites to inorganic substances such as carbon black, metal oxides, and minerals. It provides a detailed inventory of the dust's composition.