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Clean air, year round.

by Haldane King

We are a nation of citizen scientists who will one day use regulation-grade, low-cost sensors to measure and report outdoor air quality to the world. However, what happens when we confront the air inside buildings? We know that air in our homes is more polluted than outside. This makes indoor air quality testing very appealing because we spend most of our time inside (unless you enjoy a bit of backyard glamping!)

If we suspect an air pollution problem in our homes, sometimes our first instinct is to measure contaminant levels. Indoor air quality testing can be a valuable resource, but we must be strategic and selective about the process. According to the Connecticut Department of Public Health, measurement of pollutants (other than radon) will be most useful when a specific contaminant is already a likely suspect.

Depending on your situation, home air-quality tests of different levels of accuracy and price may be warranted. As for radon, which can be present in any home (according to the U.S. Consumer Product Safety Commission and the U.S. Environmental Protection Agency), there are inexpensive do-it-yourself kits. Ultimately, we all want to reduce the levels of the elusive but manageable pollutants hiding in our homes.

Indoor Air Quality Testing and Contaminants

Unfortunately, we cannot test for all indoor pollutants in one go–if we could, you would not need to read this article! Testing for several contaminants can be expensive and overwhelming, but if you approach the problem like a detective, basing your choice of air quality test kits on informed suspicions, you are likely to solve the mystery.

The EPA describes common indoor pollutants that might be present in your home:

  1. Biological pollutants, like mold, dander, pollen, dust mites, and bacteria
  2. Chemical pollutants, which include volatile organic compounds (VOCs) like formaldehyde, and the other chemical pollutants lead and radon
  3. Combustion pollutants, like carbon monoxide and tobacco smoke (incidentally, VOCs and other chemical pollutants may result from combustion)

Costs of Indoor Air Quality Testing by Pollutant Type


Bar graph with costs of indoor air quality testing


Biological Pollutants

According to the EPA, some biological pollutants cause allergic reactions, which include: hypersensitivity pneumonitis, allergic rhinitis, and some types of asthma. Viruses and toxins from microorganisms that are spread through the air can also cause disease. Symptoms of health problems could be sneezing, watery eyes, coughing, shortness of breath, and dizziness.

Testing for Biological Pollutants

We must remember that blind testing for biological allergens is not recommended–it is best to have a hunch or at least a lineup (or, as the British say, an identity parade) of likely suspect contaminants as to which ones are contributing to your indoor air pollution. After an initial walkthrough of your home and taking preventive measures, if you have not experienced any relief in symptoms or are not convinced that your air is clean, indoor air quality testing might be a good option.

If you are interested in testing indoor air quality for the allergens described below, there are analysis services provided by a company called INDOOR Biotechnologies, Inc. These tests are specific for one or up to 14 common biological pollutants, from house dust mite allergens to animal allergens to pollens. The company’s analysis technology is called Multiplex Array for Indoor Allergens (MARIA), which has been considered in research studies like the one by Winn et al. (2016) as an objective standard. If you are in the market for a flexible analysis service, this one might prove useful.

You would need to submit a dust or air sample (for the dust sample you can use their proprietary dust collector, and for the air sample, you can use an aerosol impactor, such as the models available from The price ranges from $75 for their lab to test for one allergen, to $345 for testing all 14. For a more detailed overview of some common biological contaminants, what to do if you suspect a problem, and how (or if) to test for them, we’ve summarized three major household biologic contaminants below.


Let us begin with mold–that fungus we have always cringed to see, but that which also gave us our first antibiotic. Mold grows both indoors and outdoors and can float into your home via doorways, windows, and vents, or be carried indoors by clinging to clothing or shoes.

Close up of white mold

The CDC reports that for those who are sensitive to molds, they can cause nasal stuffiness, irritation of the throat, coughing or wheezing, or eye irritation. Surprisingly, the Institute of Medicine found evidence that otherwise healthy people can also experience upper respiratory symptoms, wheeze, and cough.

Before we scramble to get out our kits to test for home air quality, we must take a second to sniff for any musty air and inspect any likely places for mold to take up residence. Moreover, we will not need our magnifying glasses or microscopes this time, because as the EPA says, usually if mold is visible there is no need for sampling. Any air quality testing for mold will likely be complicated by the ubiquitous nature of mold spores (problems arise when there are large quantities of mold spores). Instead, it is best to look for mold in common problem areas in your home, clean up any visible signs, and remedy the conditions that led to the mold growth in the first place (e.g., excessive humidity).

House dust mites

The thought of dust mites that live in mattresses, bedding, upholstered furniture, carpets, and curtains is truly creepy, and unfortunately, they are present in every home no matter how clean it is. Dust mite allergens are one of the most powerful of the biological allergens and can be an asthma trigger. Asthma triggers in general may cause symptoms like coughing, tightness in the chest, wheezing, and breathing problems.

Luckily, the National Institutes of Health (NIH) describes ways to reduce dust mite levels, including:

  • Use a dehumidifier or air conditioner to keep humidity at about 50% or below (because dust mites love warm, humid places)
  • Cover your mattress and pillows in allergen-impermeable covers
  • Wash bedding in hot water (at least 140°F, or 60°C) to kill dust mites (or, if it is not washable, it can be frozen overnight)
  • Vacuum to remove allergens and use a damp rag to remove dust

The testing company mentioned above, INDOOR Biotechnologies, Inc., manufactures a test kit for home air quality, specifically for dust mite allergens. The test kit currently runs at $49.95.


Tigers and lions and allergy season, oh my! During the spring, summer, and fall, weeds, grasses, and trees release tiny pollen grains into the air. These floating pollen grains then hitch a ride on people and pets and are carried inside.

picture of dandelion and pollen in the air

The U.S. National Library of Medicine reports that some of the tiny pollen grains that enter your nose and throat can trigger a type of respiratory allergy called hay fever.

The symptoms of hay fever include:

  • Sneezing
  • Coughing
  • Itching eyes, nose, and throat
  • Red and watery eyes

Some preventive strategies of increased pollen exposure include:

  • Staying indoors from 5:00 am to 10:00 am when outside pollen counts are highest
  • Keeping the windows in your home and car closed
  • Drying your clothes in a dryer instead of hanging them up outside
  • Avoiding a choice of grass or trees in your yard that produces high levels of pollen

The testing service mentioned at the beginning of this section will only analyze a sample for two types of pollen allergens, the birch tree allergen, and the Timothy grass allergen, for a price of $75 per type.

Chemical Pollutants

General Volatile Organic Compounds (VOCs)

According to the EPA, volatile organic compounds (VOCs) are organic compounds that easily become vapors or gases, hence their “volatile” nature. Next, the “organic” part stems from the chemical definition of organic compounds, which requires that they contain the element carbon. Some organic chemicals naturally occur in living things, but many are synthetic and found nowhere in nature.

We have different chemical products in our homes, which can release organic compounds while they are being used, but surprisingly, even when they are stored! The usual suspects that contain VOCs are paints, cleaners and disinfectants, stored fuels, wood preservatives, and dry-cleaned clothing. Other products that can contain VOCs are building materials, furnishings, office equipment, and graphics and craft materials.

Cleaning products in a bucket on a table

The potential for an organic chemical to cause health effects will depend on the toxicity of the VOC–some are very toxic, and others create no known health problems. The NIH says that long-term exposure to VOCs can cause kidney, liver, and central nervous system damage. Short-term exposure to volatile organic compounds can result in eye and respiratory tract irritation, headaches, dizziness, fatigue, loss of coordination, allergic skin reactions, memory impairment, and nausea.

The EPA has several actionable tips to reduce levels of VOCs in the home including suggestions to:

  • Increase ventilation and provide fresh air when you use products that release VOCs.
  • Follow any precautions or directions stated on product labels.
  • Discard unused or minimally-used old chemicals safely and only buy quantities that you expect to use soon.
  • Keep benzene (a known carcinogen) exposure to as little as possible (sources include environmental tobacco smoke, stored fuels, paint supplies, and auto emissions).
  • Keep exposure to perchloroethylene emissions from materials that just have been dry-cleaned to a minimum.

As far as home air testing for VOCs, there are a few home testing kits available, including one from Home Air Check that runs for $130.74. The kit includes a sampling pump and sorbent sample collector, which once completed is sent to the company’s American Industrial Hygiene Association (AIHA) accredited lab. The kit will measure the Total Volatile Organic Compound (TVOC) level within the home.

But before we scramble for the test kits, we should keep in mind that though the lab where the sample will be sent is accredited, ultimately air samples should be collected by a trained technician. Collection by a professional means that the process is within accepted standards and the samples are representative of typical conditions. Home sampling kits may allow for some idea of VOCs concentrations in the home, but without the experience of a trained professional, errors in sampling method may introduce inaccuracies in the data.


Formaldehyde is a well-known VOC, and like all its volatile organic siblings, we are exposed when the chemical is released into the air, and we breathe it in. The EPA says the most common place to find formaldehyde is in the manufacturing of urea-formaldehyde resins, which are used in particleboard products. It is also found in building materials and insulation, household products like glues, permanent press fabrics, paints, and paper products. The chemical is even used as a preservative in some medicines, cosmetics, and other personal care products.

According to the Agency for Toxic Substances & Disease Registry (ATSDR), the health effects of formaldehyde range from eye, nose, and throat irritation to neurological effects and increased risk of asthma and allergy symptoms. The Department of Health and Human Services (HHS) has determined that formaldehyde is a known human carcinogen.

The ATSDR says the easiest way to reduce formaldehyde (or other VOC) levels is by opening windows and using fans to bring in fresh air–basically, increasing ventilation, as mentioned above. Removing formaldehyde-containing products, sealing unfinished manufactured wood surfaces, and washing new permanent-press clothing before wear can also help lower levels of formaldehyde.

The CDC says you probably do not need to test for formaldehyde, except if you still smell strong chemical odors, or you have breathing problems and irritation only when you are at home. If you choose to go with the option of indoor air quality testing for formaldehyde, the CDC says you should hire a professional who has the right training and equipment.

These professional tests can be expensive, however, and cannot tell you which products release the most amount of formaldehyde in the home. As far as the home air quality tests, the results can differ based on where and for how long you do the testing and usually cannot be compared to professional tests. But if you would like an initial snapshot, there are home test kits that provide a measure of the average indoor level of formaldehyde over a period of five to 10 days and cost about $90, according to the California Environmental Protection Agency Air Resources Board. The price of a Home Air Check formaldehyde test kit runs at $94.44.


Lead is one of the few elements known to ancient peoples. The Romans used lead pipes in their water systems as well as in pots and pans, and modern scientists think that many became ill and potentially died because of this usage.

It was only in the late 19th and early 20th centuries that the negative health effects of lead were discovered. Most European countries banned the use of lead in paint for interiors by 1930. In the 1970s, the U.S. passed laws to reduce lead air pollution, and the primary lead product by the end of the 20th century was the lead-acid battery.

In 1978, the U.S. government prohibited the use of lead-containing paint for consumers. If your house was built before 1978, the chances are that it has lead-based paint. This is worrisome, because the U.S. Consumer Product Safety Commission (CPSC) and the EPA say that old lead-based paint is the most significant source of lead exposure in the U.S. But let us not panic just yet–if the paint is not deteriorating (peeling, chipping, chalking, cracking, or damp) or damaged, then the lead paint is usually not a problem, according to the EPA. Dangerous exposure only occurs from lead-based paint that is improperly removed by scraping, sanding, or open-flame burning.

Old paint cracking on a wall

When lead becomes airborne, the chemical can enter the body when a person breathes or swallows lead particles. The CPSC and EPA say that lead can affect all systems of the body–at high levels, it can cause convulsions, coma, and even death, and at lower levels, it can harm the brain, central nervous system, blood cells, and kidneys. For fetuses and young children, whose bodies are still growing, the effects of lead can include delays in physical and mental development, lower IQ, shorter attention span, and behavioral problems. In 1991, the Secretary of the Department of Health and Human Services said that lead was the “number one environmental threat to the health of children in the United States.”

To reduce lead exposure for children, it is essential to:

  • Keep play areas as dust-free and clean as possible
  • Have children wash their hands before meals and sleep
  • Wash toys and stuffed animals often
  • Mop floors and wipe window ledges and any chewable surfaces like cribs with a warm-water solution of powdered automatic dishwasher detergent (because of its high phosphate content that can remove lead in dust)

Here are some more tips to reduce levels of lead:

  • Never remove lead paint yourself (people have been poisoned by the large amounts of lead dust that comes from scraping or sanding lead dust)
  • Use doormats to wipe feet before entering the home
  • Change your clothes before you return home if you work with lead in your job or hobby and wash the clothes separately

The EPA outlines additional tips on how to make your home lead-safe and protect your children in a great online resource.

Testing for Lead

The California Department of Public Health recommends that you consider lead testing if you have children in your home and: 1) your house was built before 1978, or 2) your house is near a freeway or roadway where leaded gasoline and its exhaust could have polluted the soil.

The EPA has established specific criteria for lead test kits; an EPA-recognized lead test kit, when used by a professional with the right training, can reliably determine if lead-based paint is not present in the home.

One of the EPA-recognized lead test kits for home use is 3MLeadCheck, which contains swabs that can detect lead on must surfaces within 30 seconds. This test kit will run between $10 on for two swabs and $22.50 for eight swabs. Another test kit is the D-Lead® Lead Paint Test Kit, which costs $36 for seven tests.


Radon, whose name is derived from radium, was discovered in the year 1900 by the German physicist Friedrich Ernst Dorn. One hundred years later, the world learned that radon is indeed the second leading cause of lung cancer in the United States. However, how are you exposed in your home to this radioactive, colorless gas, which is formed outside in the soil? The EPA says that radon moves up from the ground into homes through cracks and holes in the foundation. It is estimated that one in fifteen homes in the U.S. have elevated radon levels.

The health risks from living with radon stem from breathing radioactive particles that become trapped in the lungs and can result in tissue damage, which can lead to lung cancer over a lifetime. However, not everyone exposed to higher levels of radon will develop lung cancer.

The EPA and the Surgeon General recommend indoor air quality testing for radon in all homes below the third floor. There are many inexpensive, air-quality test kits for radon to be found online or in home improvement stores. There are short-term test kits that stay in your home from two to 90 days, while long-term tests remain for more than 90 days. A long-term test will give you a measurement that better indicates your home’s average year-round radon level. The National Radon Program Services at Kansas State University has discounted radon test kits that you can buy online at $15 per short-term test kit and $25 per long-term test kit.

The EPA recommends taking a short-term test as the first step. If you find that your radon level is 4 picocuries per liter (pCi/L) or greater, the EPA recommends that you follow-up with a second test–a short-term test if your result is high, especially if it is twice the 4 pCi/L level, or a long-term test if you would like a clearer picture of your home’s average year-round radon level. If your second long-term test result is 4 pCi/L or higher, or the average of your short-term test results is 4 pCi/L or higher, fixing your home would be the next step.

There are many proven methods to reduce the radon level in your home, and the primary way is by using a vent pipe system and fan. The cost will depend on your home, but for most, it can be fixed for about the cost of a simple home repair. Lowering radon levels requires technical knowledge and skills, and it is best to work with a contractor who has been trained to fix radon problems.

Combustion Pollutants

Environmental Tobacco Smoke

Environmental tobacco smoke (ETS), or secondhand smoke, is a complex mixture that comes from the end of a burning cigarette, pipe, or cigar, as well as the smoke exhaled by the smoker. You can compare ETS to the flaming cauldron from Shakespeare’s Macbeth, because the smoke is a mixture of over 4,000 compounds, and over 40 of them are known carcinogens, according to the CPSC and the EPA. A 1992 EPA report concluded that exposure to ETS causes about 3,000 lung cancer deaths among nonsmoking adults.

ETS decreases the respiratory health of hundreds of thousands of children–if parents smoke in the presence of infants and young children, the smoke can cause an increased risk of respiratory tract infections like pneumonia and bronchitis. Children may also have more symptoms of respiratory irritation like a cough. Kids with asthma are especially at risk, as ETS can increase the number of episodes and the severity of symptoms.

As you know, the number one way to avoid the health effects of ETS is not to smoke or permit others to smoke inside of your home. It may seem unnecessary to test for ETS in a smoking household. However, according to a study by Rosen et al. (2015), there may be real benefits to the measurement of tobacco smoke air pollution. The analysis may persuade parents to have smoke-free homes to protect children from harmful ETS, though the Rosen et al. (2015) study calls for improvement in the testing process. At the consumer-level, Home Air Check sells air quality test kits for tobacco smoke at $103.24 per kit.

Carbon Monoxide (CO)

Another combustion pollutant is carbon monoxide (CO), a colorless, odorless gas that at high concentrations, can cause unconsciousness and death. The CPSC and the EPA say that pollutant sources include unvented kerosene and gas space heaters, woodstoves, fireplaces, and gas stoves. The primary pollutants that are released into the air are CO, nitrogen dioxide (NO2), and particles.

At high concentrations, CO can be fatal. At lower levels, CO causes symptoms like headaches, dizziness, weakness, nausea, confusion, and fatigue. The symptoms of CO poisoning are sometimes confused with the flu or food poisoning.

The U.S. Consumer Product Safety Commission (CPSC) recommends that every home have a carbon monoxide alarm that meets the most recent Underwriters Laboratories (UL) 2034 standard or International Approval Services 6-96 standard. One example is this carbon monoxide alarm currently listed on for $38.74. Also, the CPSC recommends that consumers have a professional inspection of all fuel-burning appliances like furnaces, stoves, fireplaces, clothes dryers, water heaters, and space heaters, to detect dangerous carbon monoxide leaks. The Commission also recommends a professional inspection every year of chimneys, flues, and vents for leakage and blockage by debris.

Carbon monoxide detector

Source Control Before Testing Your Indoor Air Quality

So now for some final points to consider–the EPA’s advice to improve your air quality, without spending a dime (or at a very low cost):

  • Control the source of pollution–whether it is mold or animal dander or VOC products, usually the best way to improve the quality of your indoor air is to get rid of or reduce the individual sources of pollution.
  • Ventilate your home–filling your home with fresh air, when possible, helps reduce pollutants inside. Ventilation can mean opening windows and doors or having bathroom and kitchen fans exhaust to the outdoors.
  • Change filters often, such as central heater and air conditioner filters.
  • Adjust humidity levels to be between 30 and 50 percent.

You have finally arrived at the end of this enormous home air testing guide, and if you are still reading, truly you deserve a nice, hot cup of tea. We hope that this guide has answered your questions about testing for indoor quality, given you the tools to determine the best way to improve the air in your home and, ultimately, proposed ways to better the health of you and your family.

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