What is Indoor Air Pollution? Causes, And Effects

You probably know it can be harmful to breathe in polluted air when you’re outside. The same is true for when you’re indoors. We spend about 90% of our time indoors – at home, work, school, or when we go to shops or restaurants.

What is Indoor Air Pollution?

Indoor Air Quality (IAQ) refers to the air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants. Understanding and controlling common pollutants indoors can help reduce your risk of indoor health concerns.

Indoor air pollution is dust, dirt, or gases in the air inside buildings such as your home or workplace that could be harmful to breathe in. Poor indoor air quality has been linked to lung diseases like asthma, COPD, and lung cancer. It has also been linked to an increased risk of heart disease and stroke. 

Types of air pollution include:

  • Particulate matter (pm) – tiny particles of dust and dirt in the air, such as soot and dust mites
  • Gases – for example carbon monoxide, nitrogen oxide, and sulphur dioxide

Indoor air pollution can be caused by anything from gas stoves and wood burners, to dampness and mold.

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Indoor Air Pollution
Indoor Air Pollution

Who can be affected by poor indoor air quality?

Anyone can be affected by indoor air pollution. If you live with a lung condition, such as COPD, asthma, or bronchiectasis, you’re more likely to be affected by poor air quality as your lungs are more sensitive – although not everyone has the same reactions to the dust, dirt, and gases in our homes.

If you have a severe lung condition you might find it harder to move around, so may spend more time indoors. This means you may have more contact with things that affect the air you breathe indoors. These could include cigarette smoke, cleaning products, or mold.

Children are particularly vulnerable to poor indoor air quality as their lungs are still developing. Children’s airways are smaller, so inflammation caused by indoor and outdoor air pollution can cause them to narrow more easily than in older people.

Sources of Indoor Air Pollution

There are many sources that can be responsible for indoor air pollution, some of which are recognizable due to their odor, but there are many that fly under the radar.

Sources of indoor Air Polution


A mold is a form of fungus which grows from spores that latch onto damp areas in buildings. It digests the materials it lands on and can grow on many types of surfaces. It is prevalent in moist environments and is most common during the winter months and in more humid climates.

As there are many types of fungus that cause mold, it can take on a wide variety of features. Mold may be white, black, green or yellow, and can appear to be slick, fuzzy, or rough in texture.

Worryingly, mold can release a range of hazardous toxins into the air and can cause many different symptoms, and is a particular concern to babies, children, older adults, and those with existing skin problems, respiratory problems, or weakened immune systems.

Tobacco Smoke

A major cause of indoor air pollution, environmental tobacco smoke, or secondhand smoke, causes over 40,000 deaths in the U.S. each year. The inhalation of cigarette smoke is particularly harmful to children, increasing the risk of sudden infant death syndrome (SIDS), severe asthma, ear problems, and acute respiratory infections.

Moreover, cigarette smoke contains at least 70 carcinogens, chemicals that have been proven to cause cancers, as well as around 7,000 other chemicals that your body could do without. When inhaled, these chemicals can cause illnesses such as chronic obstructive pulmonary disease (COPD) and other cardiovascular diseases which lead to heart attacks, as well as other serious complications.


Carpets act like traps for indoor pollutants, easily absorbing mold spores, particulates from smoke, allergens, and other harmful substances. Research has found that even some toxic gases can settle into carpets. While some may argue that this trap keeps occupants safe, pollutants caught in carpets can be easily disturbed simply by walking on them.

Household Products

Many day-to-day products present in almost every home can cause indoor air pollution. These include:

  • Cleaning agents and disinfectants
  • Paints
  • Glues and solvents
  • Personal care products
  • Air fresheners


These products may emit volatile organic compounds (VOCs), which can cause issues such as eye, nose, or throat irritation, headaches, nausea, organ damage, and even cancer in some extreme cases.


Many homes and offices contain space heaters, ovens, furnaces, fireplaces, and water heaters that burn fuels such as gas, kerosene, oil, coal, or wood for energy. As combustion can be extremely dangerous, most appliances are rigorously tested to ensure they are safe for use.

However, if the appliance is faulty, it can produce toxic gases such as carbon monoxide, sulfur dioxide, and other compounds including hazardous aldehydes.


A completely odorless and inert gas, radon can seep up through the ground and diffuse into the air in your building. When it undergoes decay, radon emits radiation which can attach to dust particles and pass into the lungs causing damage. Although it may seem strange, surveys have shown that radon concentration indoors is an order of magnitude higher than those typically found outdoors.

Pet Dander

You might not think of pet dander when you think of indoor pollutants, but for many allergy sufferers, it’s an acute irritant that can make some indoor environments vexing. Pet dander is comprised of microscopic flakes of skin shed by household pets, meaning that hairless breeds can cause symptoms like coughing, sneezing, watery eyes, and chest tightness.

It is important to note that air temperature, humidity, and circulation can produce symptoms similar to those of indoor air pollution, and simply turning down the thermostat may help.

Effects of Indoor Air Pollution

Health effects from indoor air pollutants may be experienced soon after exposure or, possibly, years later.

Health effects associated with indoor air pollutants include:

  • Irritation of the eyes, nose, and throat.
  • Headaches, dizziness, and fatigue.
  • Respiratory diseases, heart disease, and cancer.

Immediate Effects

Some health effects may show up shortly after a single exposure or repeated exposure to a pollutant. These include irritation of the eyes, nose, and throat, headaches, dizziness, and fatigue. Such immediate effects are usually short-term and treatable.

Sometimes the treatment is simply eliminating the person’s exposure to the source of the pollution if it can be identified. Soon after exposure to some indoor air pollutants, symptoms of some diseases such as asthma may show up, be aggravated, or worsened.

The likelihood of immediate reactions to indoor air pollutants depends on several factors including age and preexisting medical conditions. In some cases, whether a person reacts to a pollutant depends on individual sensitivity, which varies tremendously from person to person. Some people can become sensitized to biological or chemical pollutants after repeated or high-level exposures.

Certain immediate effects are similar to those from colds or other viral diseases, so it is often difficult to determine if the symptoms are a result of exposure to indoor air pollution. For this reason, it is important to pay attention to the time and place symptoms occur.

If the symptoms fade or go away when a person is away from the area, for example, an effort should be made to identify indoor air sources that may be possible causes. Some effects may be made worse by an inadequate supply of outdoor air coming indoors or from the heating, cooling or humidity conditions prevalent indoors.

Long-Term Effects

Other health effects may show up either year after exposure has occurred or only after long or repeated periods of exposure. These effects, which include some respiratory diseases, heart disease, and cancer, can be severely debilitating or fatal. It is prudent to try to improve the indoor air quality in your home even if symptoms are not noticeable.

While pollutants commonly found in indoor air can cause many harmful effects, there is considerable uncertainty about what concentrations or periods of exposure are necessary to produce specific health problems.

People also react very differently to exposure to indoor air pollutants. Further research is needed to better understand which health effects occur after exposure to the average pollutant concentrations found in homes and which occur from the higher concentrations that occur for short periods of time.

Prevention of Indoor Air Pollution

There are simple steps we can do to reduce pollution indoor. However, the air in their home, which they likely spend hours breathing every single day, they do have more control over. Preventing and reducing indoor air pollution can have numerous health benefits and is well worth the work to accomplish.

Preventing indoor air pollution can be done in a variety of ways. These include:

  • Proper ventilation. The air inside may contain chemicals from a variety of sources: cleaners, hair sprays, cooking, or nail polishes. In low concentrations, these may be harmless, but if they cannot dissipate to the outside, they will build up in the air inside a home and cause health problems.
  • Don’t smoke in or near the home. Cigarette smoke, even secondhand, is one of the leading causes of lung cancer, and the smoke sticks around. Ban smoking from a home and its premises to prevent this pollution.
  • Eliminate odors instead of covering them. When something is putting off a bad smell, it can be tempting to use air freshener to cover it up. However, this creates a cloud of chemicals in your home. Find the source of the odor and get rid of it, or use baking soda to eliminate the odor in a healthier fashion.
  • Prevent pests. Insects and rodents carry all kinds of airborne contaminants into a home. Seal your home properly and store food in safe containers to reduce the likelihood of attracting such pests.
  • Control pets. While pets are a beloved part of many families, they are also sources of pet dander and dust mites. Banning them from sleeping on people’s beds or laying on furniture is a reasonable compromise to keep their effect on indoor air pollution to a minimum.
  • Dust often and well. Dust is the major source of aptly named dust mites and many other allergens. Not allowing dust to build up anywhere in a home is an important step to preventing indoor air pollution.
  • Clean floors regularly. This may seem odd, but a home’s floors affect air quality. All dust eventually settles on the floor, only to be stirred up again when someone walks on it. Vacuuming carpets and sweeping and mopping bare floors helps ensure healthy indoor air quality.
  • Keep floor mats at every door. Putting large floor mats at every entry point to a home help prevent large quantities of dirt, dander, plant particulates, and other pollutants from spreading throughout a house.
  • Use natural cleaners. Natural cleaners and elbow grease accomplish the same cleanliness as chemical-laden cleaners, without polluting the air.
  • Do crafting projects in well-ventilated spaces. Some crafting materials, such as glues, can produce noxious fumes. These materials are best used in rooms with open windows.

Preventing indoor air pollution is not a complicated process, but it does require effort. The work pays off in increased health for the family living in a home with healthy air quality.

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