Enhancing Your Home Inspection Services: A Comprehensive Guide to Indoor Air Quality Testing

September 9, 2021 | 
home inspector testing indoor air quality

The lack of fresh, well-ventilated air in modern homes contributes to potentially hazardous situations. Research indicates that indoor air quality can be worse than outdoors

Indoor air quality (IAQ) has become a major factor for new homebuyers. Poor air quality can have immediate health effects such as fatigue, headaches and dizziness, and irritation of the eyes, nose, and throat. Poor IAQ can also have long-term dangers such as heart disease, cancer, and respiratory diseases. 

Home inspectors may want to be familiar with air quality issues. As a professional home inspector, you should not only understand the major causes of air quality problems, but you may also wish to add IAQ testing to your arsenal of services.

In this post, we’ll look at the major causes of indoor air quality issues. Then, we’ll cover a few ways you can provide IAQ testing—and additional peace of mind—for your home inspection clients.

Causes of indoor air quality problems

Indoor air quality (IAQ) is the quality of the air inside and around buildings and structures, especially relating to the health of people and animals. 

Poor air quality can be caused by many things, ranging from pests, moisture and mold, radon, household cleaning products, and smoke—to name a few. Let’s look at eight of the most common causes of poor indoor air quality.

Poor ventilation

With improvements in building techniques and materials, more and more homes are built to be well-insulated and energy-efficient. This trend may be great news for saving money on energy bills, but it does mean that much less air is circulated.

So if a dangerous or irritating substance finds its way into the home’s air, it’s much less likely to escape or be diluted by fresh air coming in. 

Humidity and water damage

Excess moisture is one of the most common conditions that affect air quality. Homeowners in humid climates, especially, should be aware of the potential growth of mold and mildew in places like basements, bathrooms, and behind washing machines and water heaters.

Of course, mold can also be present inside walls or other places that aren’t visible, so it isn’t always easy to spot. If enough mold builds up, it can release spores into the air that can make inhabitants sick. 

Tobacco Smoke

If a member of the home is a smoker, environmental tobacco smoke (ETS) can contaminate the home’s air quality. ETS and secondhand smoke can affect the respiratory health of all of the home’s occupants, leading to an increased risk of:

  • Respiratory tract infections
  • Asthma
  • Lung cancer
  • Other cancers, such as mouth, throat, stomach, and esophagus cancers
  • Heart disease


Radon is a radioactive gas emitted from decomposing uranium rocks. It is a colorless, odorless, and tasteless gas that often drifts into a home through gaps in the foundation or basement.

While small traces of radon are common and generally harmless, high radon concentrations in the air can cause serious health problems. In fact, 4 picocuries per liter (pCi/L) in the air poses the same risk as smoking half a pack of cigarettes per day.

Biological Contaminants

Biological contaminants are caused by living things, such as pets, insects, bacteria, and plant life. Some of the most common biological contaminants are:

  • Dust mites
  • Pollen
  • Viruses and bacteria
  • Pet dander and saliva
  • Droppings from rodents, cockroaches, and other pests
  • Mold and mildew

Many of these contaminants are small enough to inhale, and they often cause allergies and illness. The solution to these contaminants is usually to keep the home clean, dry and well-ventilated.

Carbon Monoxide

Carbon monoxide (CO) can be lethal if it builds up in the home. Usually, CO buildups are caused by unvented or clogged heating systems, furnaces, chimneys, stoves, fireplaces, and gas appliances. 

Due to CO danger, many modern homeowners invest in CO detectors with an alarm to alert them of a dangerous buildup of this odorless gas. If you’re inspecting a home and see it doesn’t have a CO detector, suggest your clients get one. There are many affordable models on the market, and a carbon monoxide detector can be a literal lifesaver.


Volatile organic compounds (VOCs) are dangerous gases that are present in many modern household products, like:

  • Paints
  • Cleaning products
  • Air fresheners
  • Hair spray
  • Crafting supplies
  • Other common fabrics and textiles

Usually, VOCs are emitted from newer items. Things with a “new” chemical smell—like a new rug or shower curtain—would be good candidates for suspicion. A buildup of VOCs in an unventilated space could cause symptoms like headache, dizziness, confusion, and nausea. 


Asbestos is a naturally occurring, fibrous mineral found in rocks and soil. It’s a good insulator since it’s resistant to electricity, corrosion, and heat. However, when asbestos dust is breathed in, those mineral fibers can do long-term damage to the body

Even though exposure to asbestos can cause cancer and other serious diseases, it is still used in many consumer products in the U.S. Presence of asbestos is not illegal as long as it makes up less than 1% of the product.

Asbestos can be found in many commonly found household items, such as:

  • Ceiling and floor tiles
  • Cement products
  • Roofing shingles
  • Heat-resistant fabrics
  • Paper products

Asbestos can get into the air when homeowners begin moving or disturbing asbestos materials. Remodeling can increase asbestos levels in the air, so it is a good idea to test the air quality of a recently remodeled or updated home.

Air quality guidelines and testing options for Home Inspectors

Some home inspection companies offer IAQ assessments as part of their inspection packages.

An indoor air quality assessment typically measures airborne particulates, gases, humidity, and ventilation. Unfortunately, there isn’t an all-in-one solution for measuring the potential issues with the air inside a building, so a professional assessor would need to perform several tests.

A home inspector following a standard home inspection checklist will look for common signs of indoor air quality issues, like: 

  • Signs of visible mold and/or water damage
  • Unusual moisture in building materials
  • Unusual temperature and relative humidity of the building
  • Residue from rodents and other pests

But a home inspector may also choose to offer ancillary services related to indoor air quality. Let’s look at a few of the most common additional IAQ testing services you could add to your inspection repertoire. 

Radon testing

Home inspectors can conduct a radon test using a passive or active testing device. These devices are test kits that gather air samples and are then sent to a lab for analysis. The National Radon Proficiency Program (NRPP) offers certifications in radon testing and measurement.

Carbon monoxide testing

Some home inspectors carry a portable carbon monoxide detector to let them analyze the levels of CO in the air, even when homes don’t have carbon monoxide detectors installed. These portable detectors measure CO in parts per million.

Another way home inspectors can help prevent carbon monoxide buildup is to use thermal imaging, which can identify leaks and backdrafts in the home’s heat system. These types of leaks are one of the most common causes of carbon monoxide poisoning in homes.

Asbestos testing

Testing for asbestos involves carefully collecting samples and sending them to a lab for analysis. This test should only be done by a certified professional since disturbing asbestos-laden materials can release hazardous fibers into the air. 

Home inspectors wishing to add this service to their offerings should find a training program in their state that is accredited by the EPA Asbestos Model Accreditation Plan (MAP).

Lead paint testing

These assessments are done using an XRF machine to detect lead on surfaces or by sending paint samples to a lab for analysis. Inspectors can get a professional certification from the Environmental Protection Agency (EPA) to conduct lead paint inspections. 

Indoor air quality testing FAQ

How can I tell if my home air quality is bad?

Often, poor air quality in the home will cause symptoms like coughing, sneezing, or allergic reactions. You may also feel headaches, nausea, fatigue, or dizziness. One indicator that your symptoms are caused by poor IAQ is if you feel better when you leave and then symptoms resume when you come back home.

How do you check the air quality in your home?

As a homeowner, it’s advisable to have a professional home inspector complete an air quality assessment. But there are a few options homeowners can use to conduct ongoing air monitoring:

  • Home indoor air quality monitor 
  • Carbon monoxide detector
  • Visual mold inspection
  • Home radon test

How much is a home air quality test?

According to HomeAdvisor, a full analysis DIY air quality test kit can range in cost from $150-$500. But remember that these testing kits merely notify the homeowner that something is unusual; if anything appears out of the ordinary, you will need to contact a professional to evaluate the situation and recommend a course of action.

Is an air quality test worth it?

Humans need air to breathe, like we need water and food. But while we often worry over the quality and cleanliness of what we eat and drink, most of us rarely consider the quality of the air we breathe in our homes.

Poor indoor air quality can not only be a nuisance; it can lead to flu-like symptoms, allergic reactions, and long-term health effects. The only way to know if your IAQ is up to par is to have it tested by a professional. What kind of price would you put on your respiratory health?

For home inspectors, indoor air quality should be considered a crucial ancillary service to add to your overall home analysis. 

Because IAQ impacts home occupants’ well-being, it is important to understand the various problems that can lead to poor air quality. You may also get further education and certifications in additional testing methods, like radon and asbestos, to protect your clients and offer them additional peace of mind for the years to come.

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