Major Sources of Indoor Air Pollution in Developing Countries

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Written By Jamila W.

Indoor air pollution (IAP) is increasingly recognized as a significant cause of morbidity and mortality globally. Deaths attributed to indoor air pollution globally exceed 3.2 million deaths each year. This number includes over 237,000 children aged under five who die from respiratory disease. Many of the health consequences of indoor air pollution impact populations in the developing world, where more than 2.4 billion people use inefficient stoves and open fires for cooking and heating. In this article, we examine the leading sources of indoor air pollution in poorer countries, their effects, and how indoor air pollution can be reduced in the poorest places on Earth. 

8 Major Sources of Indoor Air Pollution in Developing Countries

The leading causes of household air pollution in lesser economically developed nations are distinct from those encountered in high-income countries. This is because developing nations are challenged by poverty, resource scarcity, and a lack of infrastructure and regulation that would promote better air quality in homes, businesses, and public buildings. These eight sources of indoor air pollution reflect this entrenched disparity and the disproportionate global burden of disease from prolonged exposure to indoor pollution. 

1. Biomass burning

Biomass burning

The major source of indoor air pollution in developing countries is the incomplete combustion of biomass fuel. Over 3 billion people rely on biomass as a fuel source for cooking, space heating, and lighting. 

In communities that are affected by extreme poverty, biomass fuels like crop residues are commonly foraged by women and children. They include

  • Green (unseasoned wood)
  • Animal dung
  • Charcoal
  • Crop waste

Such fuels burn inefficiently in simple, poorly ventilated indoor dwellings. People are forced to burn biomass in open fires or stoves that cannot achieve safe or efficient combustion. 

The inadequate combustion of biomass cooking fuels is a source of elevated emissions of noxious gasses and particulates. Research has shown that between 6 and 20% of the biomass burned in domestic settings is converted into toxic emissions that include

  • Carbon monoxide (CO)
  • Sulfur and nitrogen dioxide
  • Formaldehyde 
  • Benzene
  • Creosote
  • PM 2.5 and PM10 particulates (fine particulates that carry the highest respiratory health risk)

Breathing zone exposure to these hazardous pollutants impacts the health of women and children who spend prolonged periods in indoor environments while combustion is underway. 

2. Coal

Coal is another solid fuel that many people across the developing world are reliant on for cooking and heating. In poor, underdeveloped settings, coal often burns inefficiently, releasing high concentrations of particulates, harmful gasses, and chemicals into the indoor environment.

Burning coal on inefficient stoves and fireplaces produces far higher concentrations of toxic by-products than biomass, including:

  • CO
  • Benzene
  • Total volatile organic compounds (TVOC)
  • Methane (CH4),
  • Polycyclic aromatic hydrocarbons (PAHs)

The worst exposures are during the coal combustion period meaning that people who prepare food or sit in proximity to a flaming coal fire are exposed to the highest concentration of pollutants, a risk factor for cancer and other diseases.

3. Kerosene

Though the use of kerosene has been heavily discouraged due to its association with poisonings and severe burns, it remains a commonly accessed household fuel in low- and middle-income countries.

Kerosene is particularly used for lighting. A study of the effects of burning open-wick kerosene lamps in 88 rural households in Uganda found that they contributed to raised levels of PM2.5 particulate pollution in enclosed spaces like living rooms and kitchens. This compromised the ability of the majority of households in the study to meet World Health Organization air quality standards. Similar effects have been observed with the use of kerosene for space heating.

4. Tobacco smoke

In recent decades, legislation and public health messaging have led to a fall in active smoking in developed countries. In developing countries, the opposite is true, causing the additional environmental health challenge of environmental tobacco smoke (ETS) and the increasing prevalence of passive smoking. 

Tobacco smoke

Environmental tobacco smoke pollutes indoor air with harmful volatile gasses and fine PM1, PM2.5, and PM10 particulates that are deposited deep in the airways of passive smokers. More than 40% of all children, 35% of non-smoking women, and 33% of non-smoking men are exposed to this source of life-limiting indoor air pollution.  

5. Building materials

Many developing countries have limited provision of well-constructed, ventilated, and serviced properties. Enforcement of building regulations may also be lax leading to the proliferation of haphazardly constructed slum districts built using inappropriate building materials prone to mold and mildew. 

Building materials

Poorly constructed accommodations may use materials that contain toxic substances like Volatile Organic Compounds (VOCs). Over time, these chemicals are released into the indoor environment, threatening the health of building occupants. The carcinogenic mineral asbestos, which is only banned in 50 countries, continues to be mined and used in construction across the world.

6. Microorganisms (including viruses)

The proliferation of a range of biological agents such as mold, insects, viruses, and bacteria can rapidly deteriorate the quality of room air, inducing health problems in building occupants. 

Airborne pathogens such as the influenza virus, mycobacterium tuberculosis (TB), and COVID-19 can be sustained in humid room air. This increases the potential that someone will become infected, especially if the building is overcrowded. 

The presence of smoke and particulates from tobacco or the incomplete combustion of solid fuels increases the susceptibility of building occupants to respiratory infections, allergies, and long-term lung disease. 

7. Radon gas

Radon is a naturally occurring radioactive gas that is generated by the decay of uranium deposits in rock. As uranium degrades, radon seeps into buildings through cracks and fissures. If ventilation in a property is inadequate, this cancer-causing gas can become concentrated in room air, harming the health of people who are exposed to it.   

In many parts of the developing world, indoor exposure to radon gas is a leading cause of lung cancer. The simple construction of Indian homes in many poorer communities lets radon penetrate buildings easily. Studies in India have found that radon gas is responsible for more than half of the background radiation exposure experienced by the Indian people. 

8. Burning waste 

The safe and sanitary disposal of municipal solid waste (MSW) is a challenge for every country. But in poorer nations that lack the infrastructure for waste management, many people are forced to burn their waste to get rid of it. 

Globally, almost 1 billion metric tons of waste is burned in an ad-hoc manner each year. Open burning of waste is inefficient, releasing noxious particulates, PAHs, nitrogen, and sulfur dioxide. Open waste burning not only causes outdoor air pollutants but the burning in proximity to dwellings leads to these pollutants entering properties and building up in indoor air. 

The Impact of Indoor Air Pollution on Human Health in The Developing World

Indoor air pollution has wide-ranging effects on the health outcomes of people exposed to it. In some parts of the world, the quality of indoor air is more than 100 times worse than internationally accepted safe limits. Recognized health consequences of IAP in the developing world include:

  • Cardiovascular disease
  • Low birth weight
  • Childhood acute respiratory infections
  • Acute lower respiratory infections
  • Chronic obstructive pulmonary disease
  • TB
  • Lung cancer
  • Other cancers
  • Diabetes
  • Allergies
  • Cataracts
  • Strokes and neurological disorders

In resource-poor communities, the acute and chronic health problems caused by IAP prevent income generation by affected people, leading to further impoverishment. High infant mortality due to respiratory diseases, further devastates communities. 

Interventions to Reduce Indoor Air Pollution in The Developing World

Reducing indoor air pollution in lesser economically developed countries is one of the world’s most important environmental health challenges. Achieving this objective would significantly impact not only the health but also the economic potential of people in the world’s poorest regions.

Leading non-governmental and public health organizations including the UN, World Health Organization, and World Bank have identified the following priorities for reducing indoor air pollution in lower and middle-income countries:

  1. Increasing clean fuels energy access with an appropriate change in domestic energy policy.
  2. Reducing the use of fuels that are low on the energy ladder like solid fuels.
  3. Provision of energy-efficient, clean-burning cooking and heating equipment.

Even the provision of a basic fuel-efficient cookstove has been shown to reduce indoor air pollution and solid fuel use.

In Conclusion

In lower-income countries, indoor air pollution is a pernicious problem perpetuated by poverty and a lack of infrastructure. The health burden of indoor air pollution devastates the productivity and potential of communities worldwide.  Policy adoption, investment, and targeted interventions will be necessary to improve indoor air quality and improve the welfare of the world’s poorest communities.