Indoor Air Pollution: Causes, Sources, Effects & Solutions

There’s two main types of air pollution – indoor air pollution, and outdoor air pollution.

This guide focuses specifically on indoor air pollution.

We look at the main causes and sources, the effects, the parts of the world where it causes the most harm and is most prevalent (which is mostly lower income countries and regions), and potential ways to reduce it.


Summary – Indoor Air Pollution

Indoor Air Pollution vs Outdoor Air Pollution – The Difference

Outdoor air pollution happens in the atmosphere outside

Indoor air pollution happens inside dwellings and buildings


Indoor Air Pollution In Developing vs Developed Regions

Indoor air pollution can differ in prevalence, potential impact on human health, and common types of air pollutants between developed and developing regions


Types Of Indoor Air Pollutants

Small particulates like PM10 can be some of the most damaging/harmful air pollutants

Carbon monoxide and VOC’s can also be problematic

Smoke in particular can release pollutants into the air

Different air pollutants might be prevalent in developed vs developing regions where different energy systems are used for cooking etc.


Causes & Sources Of Indoor Air Pollution

In developing countries, cooking in the open, with solid fuels and fuels like kerosene, instead of using clean, safe and modern energy systems inside the house might be one of the main causes/sources of indoor air pollution

In developed countries, smoking, use of certain products and substances that release air contaminants, and lack of ventilation can be some of the causes and sources


Potential Effects Of Indoor Air Pollution

Indoor air pollution may contribute to a range of health related diseases and illnesses, and sometimes death

Young children and women are some of those most affected in developing regions and low income areas

Those who spend the most time inside may be most at risk in general

The effects in developing regions can be far more significant

In developed regions, the effects may happen over the long term on a cumulative scale rather than in the short term

When indoor air pollutants and contaminants escape into the atmosphere outside, they may indirectly contribute to outdoor air pollution


Countries & Regions Where Indoor Air Pollution Happens The Most & The Least

Indoor air pollution may happen more frequently and be far more detrimental in developing countries where people don’t have access to cleaner, more modern, and safer electricity and energy production 

People in developing regions might use solid fuels (like wood and organic matter) more frequently, as well as kerosene for cooking, cleaning, heating etc.

Africa and South East Asia are the regions that might have the most indoor air pollution related deaths per year (along with the Middle East)

The Americas, Europe and Australia have the least indoor air pollution related deaths per year

India followed by China might have some of the highest mortality rates from indoor air pollution


Indoor Air Pollution Trends Over Time

Encouragingly, total worldwide deaths related to indoor air pollution are mostly on a steady decline over time

China is one example of a country that has seen a decline in the last decade, as well as India

Although, some countries like the DRC (Congo) might not be experiencing a decline yet


Potential Ways To Reduce Indoor Air Pollution

Some potential solutions for developing and low income regions may include but aren’t limited to:

– Using modern systems, appliances, technology and electricity for heating, cooking and lighting inside households in developing and low income regions, rather than what is currently used which is open fires & cookstoves burning coal and wood, that emit smoke with harmful air contaminants 

– Providing economic investment and financial assistance to low income or economically unstable countries 


Other potential solutions for developed regions may include but aren’t limited to:

– Increasing indoor ventilation

– Reducing the use of indoor and outdoor contaminants in products we use (or reducing the use of these products altogether). Paints, and other substances that emit VOCs for example might be substituted with other products that don’t 

– Reducing second hand sources of air contaminants like smoking


Being aware of the concept of air quality may also help i.e. the condition of the air, and what precautions people should be aware of with different air conditions.


What Is Indoor Air Pollution?

Indoor air pollution is a change in the indoor air quality

It usually involves the introduction of an air contaminant, which may or may not contribute to health issues for people inside buildings and structures that breathe in the air


Indoor Air Pollution In Developed vs Developing Countries

Indoor air pollution differs in prevalence and impact between developed and developing countries

It is more prevalent and can have more a more significant health impact in developing countries or regions 


Types Of Indoor Air Pollution

The main air pollutants may differ in prevalence between developing and developed regions:


Developing Countries

Small particulate matter in smoke is one of the main indoor air pollutants [Small particles of less than 10 microns in diameter (PM10), are among the most dangerous] (


Developed Countries

… Particulate matter, carbon monoxide and VOC’s (


Examples Of Causes & Sources Of Indoor Air Pollution

Some examples of causes and sources of indoor air pollution in developing and developed countries include:


Developing Countries – Sources

Comes mainly from lacking access to modern cooking and heating systems

Instead, solid fuels and kerosene are burnt in the open, and open stoves and inefficient cooking practices are used


Developed Countries – Sources

Comes mainly from household and outdoor products, and second hand sources like smoking

In both cases, a lack of ventilation can compound the issue.


Developing Countries – Causes

[It’s] usually caused by the inefficient use of solid fuels for cooking and cleaning [and heating]

… smoke and other contaminants [are] released from burning non modern energy sources inside the house like wood, crop residues, dung, charcoal, coal and kerosene.

– OurWorldInData


In 2018, around 3 billion people still cook using polluting open fires or simple stoves fuelled by these types of fuels (


Developed Countries – Causes

[It] is caused by things like mold, household sprays (aerosols for example), cleaning chemicals, garden sprays (insecticides for example) and so on.

[It also comes] from things like second hand tobacco smoke, the use of space heaters and paints/coatings.

– Wikipedia


Effects Of Indoor Air Pollution

Indoor air pollution may contribute to health issues and diseases, as well as death.

Young children, women, as well as those who spend the most time indoors might be some of the 

In poorer regions of the world, it’s usually more severe.

Indoor air pollution in developed countries is usually less severe.

Indoor air pollution may also contribute to outdoor air pollution.


Diseases & Health Conditions 

[Indoor air pollution can lead to] … acute lower respiratory disease, chronic obstructive pulmonary disease, cancers, and other illnesses (



In 2016, household air pollution was responsible for 3.8 million deaths, and 7.7% of the global mortality (


In total, 2.6 million people died prematurely in 2016 from illness attributable to household air pollution (OurWorldInData/Institute for Health Metrics and Evaluation (IHME)


… close to 4 million people die prematurely from illness attributable to household air pollution …

[Deaths are attributable to the following diseases in the following %’s:]

27% are due to pneumonia, 18% from stroke, 27% from ischaemic heart disease, 20% from chronic obstructive pulmonary disease (COPD), 8% from lung cancer.

– World Health Organization (WHO)


Close to half of deaths due to pneumonia among children under 5 years of age are caused by particulate matter (soot) inhaled from household air pollution (


It is predominantly women and young children who are killed by indoor air pollution (OurWorldInData)


Developed vs Developing Countries

[Indoor air pollution in developed countries tends not to be anywhere near as severe, and the cumulative effect of indoor air pollution can be more of an issue than short term exposure]

People most at risk might be people who may be exposed to indoor air pollutants for the longest periods of time such as the young, the elderly and the chronically ill, especially those suffering from respiratory or cardiovascular disease [and conditions like asthma]



Impact On Outdoor Air Pollution

When indoor air pollutants escape into the atmosphere, they may indirectly contribute to outdoor air pollution.


Countries & Regions Where Indoor Air Pollution Can Be An Issue

Indoor air pollution mortality rates impact certain regions and countries more than others.

Asia and Africa on a regional level, and on a country level, China and India have some of the highest %’s and totals.

Indoor air pollution and the associated health effects occurs largely as a result of household exposure to smoke from dirty cookstoves and fuels.

In order, these are the regions of the world that have the most indoor air pollution related deaths per year:


South East Asia

Western Pacific

Eastern Mediterranean 

… The Americas, Europe and Australia have the least.


Deaths from air pollution are ‘largely concentrated in Asia and Africa’

Approximately three-quarters of all deaths in 2016 were in Asia, with 22-23 percent in Africa & the Middle East …

At the country level – ‘India followed by China had the highest mortality figures in 2016 with 783,000 and 605,000 respectively.

– OurWorldInData


You can read more about indoor air pollution related death rates, overall trends, and how different countries are affected in the resource


Indoor Air Pollution Trends

The trends worldwide are that deaths are decreasing in total over the last few decades.

India and China have also show decreases, but the DRC has yet to show a decline.


The trends with indoor air pollution are:


Worldwide Total Deaths

Overall, ‘we see a decline in the number of pollution-related deaths since 1990, falling from 3.7 million to 2.6 million in 2016.’ (OurWorldInData)


Individual Countries

[India and China are two of the countries with the most death attributable to indoor air pollution and have] shown a significant decline in recent years.

In the last decade alone the number of deaths from household air pollution in China has approximately halved.

… This is however not true everywhere: the Democratic Republic of Congo appears to still be on the upward slope of this pattern.

– OurWorldInData


Potential Solutions For Indoor Air Pollution/How To Prevent It

Three of the biggest solutions might be:

– In developed countries …

Be mindful of the contaminants being used in the house and outside, such as products or substances that emit VOCs and other air contaminants

Be mindful of second hand sources like indoor smoking

Be mindful of the elderly and those who spend the most time inside


– In developing countries (and low income countries) …

Introduce cleaner and more modern heating and cooking systems for households.

Be mindful of women and children, and those in rural and low income areas


– Better ventilation can also help in most instances


What some other sources say about reducing indoor air pollution …


In developing countries and poorer countries … switch to modern energy sources which don’t release smoke and other harmful indoor air contaminants.

This involves switching to non solid fuels for heating and cooking such as natural gas, ethanol or electric technologies.

– OurWorldInData


An example of where and how this might be occurring is with the AKON Lighting Africa Project, which is replacing solid fuels with clean and affordable electricity in the form of solar panels/solar energy.

Improved design of stoves and ventilation systems can also reduce indoor air pollution in many poor communities, as well as raising more awareness about the issue to those most at risk






2. Max Roser and Hannah Ritchie (2018) – “Indoor Air Pollution”. Published online at Retrieved from: ‘’ [Online Resource]









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