What is Indoor Air Pollution? What Causes it?

The term “indoor air pollution” may seem a little

vague at first, but once you understand what it

actually includes you may be very surprised.

In this article, we’ll answer these three questions:

  • What is indoor air pollution?

  • What Causes indoor air pollution?

  • How Can You Reduce it?

Our goal is to reveal to you all of the key factors regarding indoor air pollutants and help you determine if this is something you should be concerned with or not.


Indoor Air Pollution Definition


The definition for what is indoor air pollution includes any toxic contaminants that are encountered within the spaces we dwell that are inside, such as our homes, schools, department stores and workplaces.

According to the California Air Resources Board, pollution builds up much more rapidly indoors than it did in the past, which results in higher levels of pollutants than outside. In fact, studies have shown that the levels can be anywhere between 25-60% greater than the outdoors.

The cause of this is mainly due to the fact that newer buildings and homes are created with tighter construction and toxic particles are not able to freely escape.

Sources of Indoor Pollutants

Now, you’re probably wondering “What causes indoor air pollution?”

Indoor pollutants come in types and forms, but the major ones you want to look out for include:

  • Tobacco smoke

  • Carbon monoxide

  • Nitrogen oxide from unvented or faulty gas appliances

  • Smoke from wood burning stoves and fireplaces

  • Volatile Organic Compounds (VOCs) including, paint, aerosol sprays, solvents, glues, adhesives, air fresheners, cleaning chemicals, etc.

  • Pet dander

  • Dust

  • Pollen

  • Mold

  • Asbestos

  • Radon

  • Lead

Volatile Organic Compounds (VOCs), smoke, pet dander, dust and mold are some of the most common indoor pollutants that are found in almost every home. Asbestos, radon and lead are not as common but pose extreme health risks.

VOC pollution exists in high concentrations indoors because it comes from so many different types of products. VOCs are released by aerosol sprays, cleaning products, paint, air fresheners, new carpets, and even building materials.

It’s always advisable to use an alternative to aerosol sprays and chemical cleaners whenever possible, and to buy paint that has zero to low VOCs (like Olympic Paints.)


In regards to pet dander, dust pollen and mold, the best option here is to keep a tidy house and/or use an air purifier to help out. There are two common types of these devices to keep the air within your home clean, HEPA filter air purifier and ionic air purifier. More information on air cleaners are below.

Associated Health Risks


The Environmental Protection Agency (EPA) estimates that we spend as much as 90% of our time indoors. And, for infants and the elderly this number is even greater.


Being exposed to indoor air pollution is a serious concern and can dramatically affect your health if you don’t take care of it.

A 1987 study by the EPA showed that indoor air pollution was the fourth highest cause for cancer out of 13 environmental problems.

in addition to cancer, indoor pollutants can cause other types of problems, including bronchitis, pneumonia and emphysema, heart disease, impaired mental function, allergic reactions, asthma attacks, liver damage and more.

Ventilation Is an Important Factor

When a home doesn’t have proper ventilation, its pollutants may build up to dangerous levels. Some homes have design features built-in which boost ventilation, while others don’t and this can be one of the contributing causes of indoor air pollution.


Homes which are made to keep indoor air in and minimize the levels of exterior air which can get inside are at higher risk for interior air pollution.


However, every home may be subject to this problem regardless of how it’s built. Therefore one of the best things you can do to reduce the level of harmful airborne toxins is to install a portable air purifier or whole home air purifying unit.

An air purifier works to remove the bad particles in the air and recirculate clean, fresh air that’s healthy to breathe.

Exterior Air Gets Inside in Many Ways


Exterior air comes in and exits through a range of processes. For example, air may enter or leave via natural ventilation. Mechanical ventilation is also a way that exterior air gets inside. There are actually many ways for air to get in and out, including joints, wall cracks and ceiling cracks, as well as cracks in walls. Any kinds of openings will let air escape or infiltrate and you’ll often find small openings surrounding windows and around doors.


When natural ventilation, such as open windows and opened doors, lets air in and out, it will affect interior air pollution levels, as well as indoor temperature. As well, mechanical devices, such as fans, are able to move air around when they are being used. How fast air enters and leaves in known by the term, air exchange level. A low air exchange level, or rate, is a trigger for interior pollution.


Whether you live in an apartment or a home, you’ll find that these types of problems may crop up. Commercial spaces are also subject to interior air issues. If you want to fix common causes of indoor pollution, it’s all about negating or minimizing the sources.


Knowing which factors influence indoor air quality will help a lot. Ventilation experts will be able to help you fix things if you don’t want to do it yourself.


How You Can Reduce It

If you suspect that your home has an asbestos, lead or carbon monoxide problem, it’s best to call a professional. Professionals can test your home for these toxins and make a recommendation for how to eradicate it.

If on the other hand, you’re experiencing issues with dust, pet dander, pollen or mold, you can easily remove these pollutants through the use of HEPA air purifier. Here’s a guide on how to find the best allergy air purifier for your needs.

An air purifier is a specialized machine that strips the air of harmful indoor pollution. Depending on the type of device you get, will determine what types of particles the product can remove. Some air purifiers are excellent at removing all types of toxins, while others, like ionic air purifiers, focus on a select few.

You can find out more about how each type of air purifier works by browsing that section of our website. We have a host of articles dedicated to educating you on this topic.

If you’d like to hire a professional indoor air quality specialist, take a look at the Indoor Air Quality Association for a recommendation.



  • Mechanical system components and associated air duct systems have the potential to collect particulate, contaminants, smoke, moisture, and gaseous emissions. Collections of these contaminants may create unsafe environmental conditions potentially affecting the performance and/or hygiene of the mechanical systems’ internal surfaces from fire and smoke residue. For these reasons, hygienic restoration of mechanical systems should be considered as part of the overall building restoration plan.

Return to IAQ FACTS​


Deseret News

Air pollution linked to memory declines among older women

New nationwide study documents Alzheimer’s like brain atrophy

By Amy Joi O'Donoghue@Amyjoi16 Nov 28, 2019, 2:20pm MST

SALT LAKE CITY — For the first time, a nationwide study reveals exposure to higher levels of air pollution is linked to greater declines in memory among older women, creating more Alzheimer’s-like brain atrophy than women who breathed cleaner air.

The findings by the University of Southern California were published Wednesday in Brain and involved data from 998 women ages 73 to 87.

“This is the first study to really show, in a statistical model, that air pollution is associated with changes in people’s brains and that those changes were then connected with declines in memory performance,” said Andrew Petkus, assistant professor of clinical neurology at the university’s Keck School of Medicine.

“Our hope is that by better understanding the underlying brain changes caused by air pollution, researchers will be able to develop interventions to help people with or at risk for cognitive decline.”

Alzheimer’s is the sixth-leading cause of death in the United States and the fourth-leading cause of death in Utah. There is no cure or treatment.

These findings not only emphasize renewed interest in the prevention of Alzheimer’s but also have relevance for Utah’s aging baby boomer population living in vulnerable areas along the Wasatch Front where air pollution spikes in winter and summer months.

Fine particulate pollution, or PM2.5, is about 1/30th the size of a human hair and is problematic in northern Utah. The pollution builds as a result of vehicle exhaust, wood burning, industrial sources, and from businesses and homes. At times, the pollution can get so bad the metropolitan areas in Utah end up on a national list for having some of the filthiest air in the country.

Nels Holmgren, director of the state’s Division of Aging and Adult Services, has not seen the study but said any new information that sheds light on Alzheimer’s will be important for Utah’s older residents.

“I think anything that informs us on how to better help people as they age, we are obviously looking forward to that,” he said. “We are always interested in new information that would be helpful and useful to our seniors in the state.”

In this new study, researchers used data from women who had up to two brain scans five years apart as part of the Women’s Health Initiative that was launched in 1993. The initiative by the National Institutes of Health enrolled more than 160,000 women to address questions about heart disease, cancer and osteoporosis.

The scans were scored based on their similarity to Alzheimer’s disease patterns. Researchers also gathered data on where the women lived and environmental information documenting fine particle pollution levels.

When all that information was combined, a picture emerged that showed the link between higher pollution exposure with brain changes and memory problems.

“This study provides another piece of the Alzheimer’s disease puzzle by identifying some of the brain changes linking air pollution and memory declines,” Petkus said. “Each research study gets us one step closer to solving the Alzheimer’s disease epidemic.”

Return to IAQ FACTS​


  Your family may

Breathe Different

feel Better, be Happier, live Longer