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 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. 

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.

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.

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.


What are the 4 major indoor air pollutants?

The Environmental Protection Agency has noted that excess moisture, volatile organic compounds, carbon monoxide, and radon are four major indoor air pollutants. They result in damp and stuffy houses.

What causes air pollution indoors?

Most indoor air pollution comes from sources that release gases or particles into the air. Things such as building materials and air fresheners give off pollution constantly. Other sources such as tobacco smoke and wood-burning stoves also cause indoor pollution. Some indoor air pollutants have been around for years.

What are 5 indoor pollutants?

According to the Environmental Protection Agency, the top five air quality problems in the U.S. are indoor air problems. Common residential indoor pollutants include excessive moisture, volatile organic compounds (VOCs), combustion products, radon, pesticides, dust particles, viruses, and bacteria.

What are some common indoor air pollutants?

Learn more about indoor air pollutants and sources of:

  • Asbestos.
  • Biological Pollutants.
  • Carbon Monoxide (CO)
  • Formaldehyde/Pressed Wood Products.
  • Lead (Pb)
  • Nitrogen Dioxide (NO2)
  • Pesticides.
  • Radon (Rn)

What is the most common indoor pollutant?

The most common indoor air pollutants include:

  • Lead (Pb)
  • Nitrogen Dioxide (NO2)
  • Pesticides.
  • Radon (Rn)
  • Indoor Particulate Matter.
  • Secondhand Smoke/Environmental Tobacco Smoke.
  • Volatile Organic Compounds (VOCs)
  • Wood Smoke.

What effects indoor air quality?

Some common indoor air pollutants that threaten indoor air quality include lead, dust mites, mold, radon, pests, carbon monoxide, pet dander, mold, and second-hand smoke.

How Does Poor Indoor Air Quality Affect Health?

The “immediate” symptoms of poor indoor air quality can often resemble a cold or allergies. You can feel fatigued or dizziness and may frequently get headaches and experienced eye, nose, or throat irritation.

Is the air in my home toxic?

The shocking fact is that the air inside your home is generally between two and five times more polluted than the air outside, says the Environmental Protection Agency. Some factors can make indoor air up to 100 times more toxic than the outdoor environment.

Why does indoor air quality get worse at night?

This is because, as the temperature drops during the nighttime hours, the atmosphere traps car emissions, CO2, and other pollutants in the house and down near the ground – and the effect is much worse if spaces inside the home are poorly ventilated.

Is indoor air more polluted?

In the last several years, a growing body of scientific evidence has indicated that the air within homes and other buildings can be more seriously polluted than the outdoor air in even the largest and most industrialized cities. Other research indicates that people spend approximately 90 percent of their time indoors.

Why is indoor air quality important?

Indoor Air Quality (IAQ) is strongly connected to health and wellbeing. Humans tend to spend a large amount of time indoors. Breathable air that’s free of health threatening pollutants can lead to a higher quality of life, lower risk of respiratory illnesses, and a reduced risk of various chronic conditions.

What is indoor environmental quality?

Indoor environmental quality (IEQ) refers to the quality of a building’s environment in relation to the health and wellbeing of those who occupy space within it. IEQ is determined by many factors, including lighting, air quality, and damp conditions.

How do you clean the air in your house?

How to Clean Air in the Home

  • Control Humidity. High humidity levels indoors will lead to excess moisture and dampness, both of which can affect your health.
  • Ventilate the Kitchen.
  • Remove Household Dust.
  • Eliminate Dust Mites.
  • Stop Indoor Smoking.
  • Avoid VOC-Containing Products.
  • Keep Air-Cleaning Devices Clean.
  • Avoid Pesticides.

Can a dusty house make you sick?

Some people joke that they’re allergic to house cleaning. But in all seriousness, allowing dust and mold to accumulate in your home can be harmful to your health. Endotoxins shed by household dust and mold spores can cause serious allergic responses, including asthma.

How do you know if your house is toxic?

How to Tell If Mold is Toxic

  • Watch out for a nasty smell: The most common sign that you aren’t dealing with any ordinary mold is a musty odor, sort of like rotting dirt of rotting leaves.
  • Look for visible growth: While toxic mold often hides in your walls, crawlspace, or attic, sometimes it is out in the open, too.

What are the symptoms of poor air quality?

Following symptoms are often linked to poor indoor air quality:

  • Dryness and irritation of the eyes, nose, throat, and skin.
  • Headache.
  • Fatigue.
  • Shortness of breath.
  • Hypersensitivity and allergies.
  • Sinus congestion.
  • Coughing and sneezing.
  • Dizziness.

Can indoor air quality affect sleep?

Sleep quality is quite important for health and daily performance. Indoor air quality (IAQ) is related to sleep quality. Although some people have a relaxed mood, and sleep in the bedrooms with low noise, moderate light, and appropriate temperature, they cannot sleep well because of poor air quality.

How dirty is indoor air compared to outdoor air?

According to the EPA, however, the levels of indoor air pollutants are often 2 to 5 times higher than outdoor levels, and in some cases, these levels can exceed 100 times that of outdoor levels of the same pollutants. In other words, sometimes the air inside can be more harmful than the air outside.

Does indoor air have less oxygen?

Indoor air pollution is 2 to 5 times more than outdoors. There’s also a lack of oxygen which is relatively lowest indoors, especially in air-conditioned environments.

Why is indoor air more polluted than outdoor?

Because there is not enough ventilation, concentrations of indoor air pollutants can build up from inside sources as they are not released into the greater outdoor expanse. The design of modern homes to reduce air leakage (with improved insulation) may also lead to lower air exchange between the indoors and outdoors.

What are the causes of indoor air pollution in which regions is indoor air pollution a problem?

Indoor air pollution is caused by burning solid fuel sources – such as firewood, crop waste, and dung – for cooking and heating. The burning of such fuels, particularly in poor households, results in air pollution that leads to respiratory diseases which can result in premature death.

How can I get fresh air in my room?

Use fans to improve airflow

  • Place a fan as close as possible to an open window blowing outside. This helps get rid of virus particles in your home by blowing air outside.
  • Point fans away from people.
  • Use ceiling fans to help improve air flow in the home whether or not windows are open.

Is dust harmful to lungs?

Dust particles and dust-containing macrophages collect in the lung tissues, causing injury to the lungs. The amount of dust and the kinds of particles involved influence how serious the lung injury will be. For example, after the macrophages swallow silica particles, they die and give off toxic substances.

Does poor air quality make you tired?

The increased presence of pollutants in the air can cause an increase in fatigue as well. Anyone who notices fatigue should take time off from overexerting in areas where air quality is bad. Headache. A very common symptom that many people have during times of poor air quality is headaches.

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