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Indoor Air Quality and Indoor Air Pollution

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Every breath we take contains millions of particles of dust, allergens, chemicals, irritants, and other tiny molecules. And while pollen and outdoor air pollution get most of the attention, studies show air quality inside homes and buildings is often worse than outside!

When you have asthma and allergies, that puts clean indoor air at the top of your must-have list.

Breathing in polluted air can lead to serious health problems, including breathing issues. Seek medical care to treat any health issues related to indoor air quality. It’s also important to work with a cleaning professional to evaluate indoor air quality.

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Why is indoor air quality important?

The air quality in public and private buildings is an important factor to your health. You can improve your health by ensuring good air quality in the indoor spaces where you live, work, learn and play. It can also improve your quality of life.

Most people spend the bulk of their time indoors, so it is important to have healthy indoor air quality. This is especially true in places where weather conditions may prevent people from going outside during certain times of the year.

Young girl coughing from indoor pollution

How does indoor air quality affect our health?

Poor indoor air quality creates health risks. It is often linked to health problems ranging from mild breathing issues to more severe symptoms.

Poor air quality can cause or worsen:

  • asthma, chronic obstructive pulmonary disease (COPD) and other respiratory diseases

  • heart disease (cardiovascular disease)

  • lung cancer

  • eye, nose and sinus irritation

  • headaches

  • fatigue

  • dizziness

Poor indoor air quality includes respiratory viruses that can be spread through the air. Viruses can further irritate existing health conditions and worsen symptoms.

HVAC professional cleaning and replacing air ducts.

What is indoor air pollution?

When many people think of pollution, they think of the air outside. But indoor air can also be polluted. Indoor air pollution could be caused by high levels of toxins or chemicals. It could be from poor air flow or ventilation, high humidity levels, or indoor temperature.

Conditions inside and outside of the building affect the indoor air. Construction quality, heating, ventilation and air conditioning (HVAC) systems, and spatial layout can factor into air quality.

What causes indoor air pollution?

There are many potential sources of indoor air pollution. High levels of indoor air pollutants can impact your health. Some sources such as building materials and furnishings may release pollutants continuously. Other sources such as smoking or dust from construction release pollutants when they occur.

Poor ventilation can lead to increases in indoor air pollution. Ventilation allows air to circulate, bringing in fresh air and diluting pollutants. Poor ventilation may be a result of poor quality HVAC systems.

Identifying and controlling common pollutants indoors can help minimize the effects of indoor air pollution.

What are the most common indoor air pollutants?

Sources of indoor air pollution can involve items common in many homes, including allergens and irritants:

  • mold
  • tobacco smoke (including secondhand smoke)
  • household cleaning products and indoor air fresheners
  • dust, dirt or soot (fine particulate matter)
  • animal dander
  • dust mites
  • cockroaches and mice
  • personal hobbies such as woodworking, metalworking, 3D printing
  • activities that include glues and adhesives

Fumes (often from cooking on stoves) also contribute to indoor air pollution:

  • gas
  • coal
  • oil
  • wood-burning
  • paint
  • lead

Gases can contribute to poor indoor air quality:

  • carbon monoxide
  • carbon dioxide
  • nitrogen dioxide
  • ammonia

Deteriorating materials can contribute to indoor air pollution:

  • insulation
  • asbestos
  • chemical coatings on furniture
  • carpets and rugs

Without proper HVAC systems, indoor spaces may let in outdoor air pollution:

  • pesticides
  • radon
  • pollen from grasses, trees and weeds
  • vehicle exhaust from nearby traffic or idling cars
  • wildfire smoke

Typically, the higher the concentration of the pollutant and the older the product, the more hazardous it is to indoor air quality.

Hand writing of a check list of the most common dangerous domestic pollutants we can find in our homes

Why is indoor air pollution worse than outdoor air pollution?

If there is little ventilation in an indoor space, pollutants can build up. This can be hazardous and lead to health problems. If there is no outdoor air to dilute the pollutants, it is easier for them to build up to unhealthy levels.

Also, many of us spend the bulk of our time inside, which can increase household air pollution exposure.

How can air quality be tested?

Your doctor or local health department may have recommendations for testing indoor air quality in your home, school or office building. They may be able to provide you with a professional service that can test for poor indoor air quality.

Several kinds of air quality testing kits are available. Digital air monitors can search for toxins such as radon, volatile organic compounds (VOCs) and carbon monoxide. Mold tests to detect mold in the air are available but they must be sent to a lab for results.

How can indoor air quality be improved?

One way to reduce household air pollution is to improve indoor air quality. Use high efficiency particulate air (HEPA) filters on your HVAC systems. The filter that comes with your HVAC system isn’t designed to help you breathe better. It just keeps dust and debris from clogging up the working parts of your system. HEPA filters can trap and block harmful particles from entering your indoor space.

Filters should be changed at least every three months. Your furnace and air conditioner unit should be serviced at least once a year. Additionally, an air purifier or air cleaner can help clear less serious pollutants.

HVAC worker is removing a dirty air filter.

How can air quality be improved naturally?

When outdoor air is good and the pollen count is low, open doors and windows for natural ventilation to clear out indoor pollution. Don’t use cleaning products with harmful chemicals – use nontoxic, fragrance-free products instead. Remove any air freshener devices.

Clean your indoor space often by vacuuming or mopping to remove less hazardous pollutants. Be sure to use a HEPA filter on your vacuum.

How do pets contribute to indoor air pollution?

Cats, dogs and other furry animals release dander from the skin, urine and feces. The proteins of these allergens can hang suspended in the air for a long time and circulate throughout your home. They can settle on furniture, carpeting and house dust. These allergens can cause allergic reactions when they are inhaled or come into contact with skin.

Do plants help indoor air quality?

There is some debate about whether houseplants can remove pollutants from an indoor air. Studies have shown houseplants can improve the air quality somewhat, especially in the immediate proximity to the plant. But there is no evidence to show they can remove harmful chemicals. In fact, opening a window may have more benefits for indoor air quality.

Additionally, be careful when choosing what houseplants to keep. Some may contain volatile organic compounds, such as bacteria, pesticides or contaminants. Also, avoid over-watering them as it may lead to the growth of microorganisms, such as mold, that may affect allergies.

See Related Pages

Reviewed by:
William E. Berger, MD, FACAAI, is a board-certified allergist and immunologist who serves as a media spokesperson and Chair of the Medical Advisory Council for Allergy & Asthma Network. He is a Distinguished Fellow and Past President (2002-03) of the American College of Allergy, Asthma & Immunology (ACAAI).