Professional Indoor Air Quality Testing: What Is Tested and How It Works

Indoor Air Quality testing can provide objective information about conditions that may not be visible or detectable by smell alone. Temperature, humidity, airborne particles, volatile organic compounds, mold spores, combustion gases, and other environmental factors can all affect the indoor environment.

A basic consumer air-quality monitor may provide useful information about certain conditions, but no single instrument can evaluate every factor that may affect the air inside a home.

Professional Indoor Air Quality testing uses different instruments and sampling methods to evaluate specific environmental conditions. At 5D Home Inspections, testing may combine direct-reading sensors, particulate counting, targeted air sampling, Thermal Desorption Tube sampling, laboratory analysis, and observations of the home.

What Does Indoor Air Quality Testing Measure?

Depending on the concerns being investigated, professional IAQ testing can evaluate a broad range of environmental conditions and airborne contaminants.

Temperature and Relative Humidity

Temperature provides important context when evaluating indoor air quality. It can influence relative humidity, condensation, ventilation, and the rate at which certain chemicals are released from building materials and household products.

Relative humidity measurements can help identify conditions associated with moisture concerns. Elevated humidity can contribute to condensation and create conditions favorable for mold growth, while excessively dry conditions may contribute to occupant discomfort.

Particulate Matter

Not everything affecting indoor air quality is a gas or chemical. Tiny airborne particles can remain suspended in the air and be inhaled.

Professional particulate counters can measure particle concentrations across multiple size ranges, including:

• 0.3 microns
• 0.5 microns
• 1.0 micron
• 2.5 microns
• 5.0 microns
• 10 microns

Particle size provides additional information about the indoor environment. Smaller particles can remain airborne longer, while larger particles can provide useful information about dust, filtration, ventilation, and other conditions.

Potential sources include outdoor pollution, smoke, cooking, HVAC systems, dust, construction activity, allergens, and other indoor and outdoor sources.

Total Volatile Organic Compounds

Volatile organic compounds, or VOCs, are gases released by many common products and materials.

TVOC testing measures the overall concentration of volatile organic compounds in the indoor environment. Potential sources include paints, flooring, furniture, cabinetry, adhesives, cleaning products, fragrances, and building materials.

TVOC measurements can be useful when investigating suspected chemical contamination or unusual odors.

Individual VOCs and the Home Contamination Index

A total VOC reading can indicate that volatile organic compounds are present, but additional analysis may provide more information about which compounds are contributing to the result. 5D Home Inspections can use Thermal Desorption Tube sampling to collect VOCs from indoor air for laboratory analysis. The process involves drawing a controlled volume of air through a specialized sorbent tube. The collected sample is then submitted to a qualified laboratory for analysis.

Laboratory analysis can identify individual compounds present in the sample. This can be useful when investigating chemical odors, renovations, newly installed materials, furnishings, cleaning products, adhesives, coatings, or other suspected sources.

The Home Contamination Index report can provide additional information about significant VOCs detected within the indoor environment, including compounds associated with EPA Hazardous Air Pollutants and odor-producing compounds.

Airborne Mold Sampling

When mold is a concern, specialized airborne sampling can provide information about fungal spores present in the air.

A calibrated sampling pump draws a specific volume of air through a collection device. The sample is then submitted to a qualified laboratory, where trained analysts examine the collected material and identify the types and quantities of fungal spores present.

Indoor samples may also be compared with outdoor reference samples or samples from other areas of the home.

Airborne mold concentrations can change based on weather, HVAC operation, ventilation, occupant activity, and other conditions. Laboratory results should therefore be considered alongside observations and moisture findings.

Airborne mold sampling is one component of an overall environmental assessment and does not by itself establish the source or cause of a moisture or mold condition.

Airborne Particulate Identification

A particulate counter can measure the number and approximate size of airborne particles, but particle counting does not necessarily identify what those particles are.

Specialized air sampling can collect airborne material for laboratory examination. Depending on the analytical method, laboratory analysis may provide additional information about the types of particles collected.

This can be useful when investigating unexplained airborne debris, excessive dust, fibers, suspected biological material, or other unusual particulate conditions.

Combining particle counting with laboratory identification provides two different types of information: how much particulate matter is present and additional information about what may be contributing to it.

What Gases Can Be Tested During an IAQ Assessment?

Depending on the assessment, professional direct-reading sensors can evaluate several gases and environmental parameters, including:

• Carbon dioxide (CO₂)
• Carbon monoxide (CO)
• Hydrogen sulfide (H₂S)
• Ozone (O₃)
• Formaldehyde
• Chlorine (Cl₂)
• Ammonia (NH₃)
• Oxygen concentration (O₂)

Different gases require different sensor technologies and measurement ranges. A generalized consumer monitor cannot accurately characterize every contaminant that may be present in indoor air.

Carbon Dioxide

Carbon dioxide is naturally produced through human respiration. Indoor concentrations can increase when occupied spaces have limited fresh-air exchange or inadequate ventilation.

CO₂ measurements can therefore provide useful information about ventilation conditions.

Carbon Monoxide

Carbon monoxide is produced by incomplete combustion. Potential sources include furnaces, boilers, fireplaces, water heaters, generators, vehicles, and other fuel-burning equipment.

Because elevated carbon monoxide can present a serious safety concern, measuring CO can be an important component of an indoor environmental assessment.

IAQ testing does not replace properly installed and maintained carbon monoxide alarms.

Hydrogen Sulfide

Hydrogen sulfide is commonly associated with a distinctive rotten-egg odor. Potential sources include sewer or plumbing conditions, certain water sources, and decomposition of organic material.

H₂S measurement can be useful when investigating persistent or unexplained odors.

Ozone

Ozone can enter a home from outdoors or be generated by certain electrical or air-treatment equipment.

Testing can help determine whether measurable ozone is present within the indoor environment.

Why Are Multiple Instruments Used for Indoor Air Quality Testing?

Indoor air quality is complex, and different contaminants require different measurement methods.

A particulate counter can measure particle concentration and size, but it cannot fully identify those particles. A TVOC sensor can measure overall VOC conditions, but it does not necessarily identify individual compounds. Laboratory VOC analysis can identify specific chemicals, but it does not replace measurements of humidity, particulate matter, or combustion gases.

Mold sampling also requires its own collection and laboratory analysis.

Professional IAQ testing therefore uses different tools for different questions.

Professional IAQ Testing vs. Consumer Air-Quality Monitors

Consumer air-quality monitors can be useful for observing general trends. However, their readings may be affected by sensor quality, calibration, environmental conditions, interfering compounds, instrument placement, and other limitations of the technology.

Professional testing involves equipment and sampling methods selected for the conditions being evaluated.

Factors such as calibration, detection range, sampling duration, airflow rate, placement, and interpretation can all affect the resulting data.

Laboratory analysis provides another level of evaluation by allowing collected samples to be examined using specialized analytical methods.

The goal is not simply to detect that something is present. The goal is to collect meaningful information that can help characterize the indoor environment.

When Should a Home Have Professional IAQ Testing?

Homeowners may consider professional Indoor Air Quality testing when investigating:

• Persistent or unexplained odors
• Excessive dust or airborne particles
• Humidity or moisture concerns
• Recent renovations
• New building materials or furnishings
• Suspected chemical contamination
• Concerns about mold or microbial activity
• Ventilation concerns
• Possible combustion-related conditions
• Unusual indoor environmental conditions

Testing can also provide information for homeowners who simply want a better understanding of the air inside their home.

A Comprehensive Approach to Indoor Air Quality

There is no single device that can accurately test for everything that may affect indoor air quality.

5D Home Inspections combines professional sensors, particulate counting, targeted air sampling, Thermal Desorption Tube sampling, laboratory analysis, and observations of the home to evaluate different components of the indoor environment. The result is a broader set of objective data that can help homeowners better understand what is happening inside their home.

If you are concerned about the air inside your home, professional Indoor Air Quality testing can replace guesswork with measurable information.

5D Home Inspections provides comprehensive IAQ assessments for homeowners looking to better understand the environmental conditions and airborne contaminants inside their homes.

Indoor Air Quality testing is an environmental assessment and is not a medical diagnosis. Individuals experiencing persistent or concerning symptoms should consult a qualified healthcare professional.