Understanding Indoor Air Pollution: Who's Definition

The World Health Organization (WHO) defines indoor air pollution as the contamination of indoor spaces by chemical, physical, or biological agents that modify the natural characteristics of the atmosphere. This includes the release of harmful pollutants such as fine particulate matter, carbon monoxide, and various other toxins. Indoor air pollution is a major health hazard, particularly in developing countries, where the indoor burning of solid fuels like wood, coal, and dung releases pollutants, impacting air quality and human health. WHO estimates that indoor air pollution causes approximately 3.8 million deaths annually and contributes to non-communicable diseases such as stroke, ischaemic heart disease, chronic obstructive pulmonary disease, and lung cancer.

Health risks and effects

Indoor air pollution is a serious issue that can have significant negative impacts on human health. The World Health Organization (WHO) defines indoor air pollution as the contamination of indoor spaces by any chemical, physical, or biological agent that modifies the natural characteristics of the atmosphere. This can include pollutants such as particulate matter, carbon monoxide, ozone, nitrogen dioxide, and sulfur dioxide.

One of the main health risks associated with indoor air pollution is the increased likelihood of respiratory problems. Poor indoor air quality can irritate the eyes, nose, and throat, and prolonged exposure can lead to respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD). Young children are especially vulnerable to the effects of indoor air pollution, as their lungs are still developing. In the UK, there is a growing trend of children spending more time indoors, which makes the health impact of indoor air quality all the more concerning.

Another concern is the link between indoor air pollution and cardiovascular issues. Fine particles from indoor smoke can penetrate deep into the lungs and enter the bloodstream, increasing the risk of heart disease. Additionally, certain pollutants such as radon and carbon monoxide are known human carcinogens, with radon being the second-leading cause of lung cancer. The use of polluting fuels and stoves for cooking and heating, such as kerosene and unprocessed coal, further exacerbates the problem.

The health effects of indoor air pollution can vary depending on individual sensitivity, age, and pre-existing medical conditions. Some people may experience immediate reactions such as headaches, dizziness, and fatigue, while others may not exhibit symptoms until years after exposure. Prolonged exposure to indoor air pollutants can also lead to serious and potentially fatal health issues. Certain building materials, furnishings, and household products can continuously release pollutants, contributing to the degradation of indoor air quality over time.

The impact of indoor air pollution is particularly pronounced among women and children in low- and middle-income countries. They are often responsible for household chores, including cooking and collecting firewood, which exposes them to harmful smoke from polluting stoves and fuels. Additionally, the ingestion of kerosene is the leading cause of childhood poisonings, and the use of inefficient devices for cooking, heating, and lighting increases the risk of severe burns and injuries.

Sources of indoor air pollution

According to the World Health Organization (WHO), around 2.1 billion people worldwide cook using open fires or inefficient stoves fuelled by kerosene, biomass (wood, animal dung and crop waste) and coal, which generates harmful household air pollution. Household air pollution was responsible for an estimated 3.2 million deaths per year in 2020, including over 237,000 children under the age of five.

• Outdoor air pollution, such as motor vehicles, industrial facilities, and forest fires.
• Inadequate ventilation, which can increase indoor pollutant levels by not bringing in enough outdoor air to dilute emissions from indoor sources.
• High temperature and humidity levels, which can increase the concentration of some pollutants.
• Building materials, furnishings, and products like air fresheners, which can release pollutants continuously.
• Activities like smoking, cleaning, redecorating, or hobbies, which release pollutants intermittently.
• Unvented or malfunctioning appliances or improperly used products, which can release dangerous levels of pollutants.
• Biological pollutants, including plants, people, animals, and mould or mildew.
• Radon gas, which can enter homes built on uranium-rich soil or rock.
• Asbestos, which can be released into the air during improper removal.

It is important to note that the relative importance of any single source of indoor air pollution depends on the amount and hazard level of the emitted pollutants.

Clean air initiatives

Indoor air pollution is caused by the use of inefficient and polluting fuels and technologies in and around the home. Pollutants include small particles that penetrate deep into the lungs and enter the bloodstream, and exposure is particularly high among women and children. WHO defines clean fuels and technologies as solar, electricity, biogas, liquefied petroleum gas (LPG), natural gas, alcohol fuels, and biomass stoves that meet emission targets.

WHO has issued the following guidelines to address indoor air pollution:

• The Guidelines for Indoor Air Quality: Household Fuel Combustion, which offer practical evidence-based guidance on clean fuels and technologies, including recommendations discouraging the use of kerosene and unprocessed coal.
• WHO also provides technical support and capacity building to countries and regions to evaluate and scale up health-promoting household fuels and technologies.
• WHO promotes interventions and initiatives for healthy sectoral policies, addressing key risks to health from indoor and outdoor air pollution and contributing to achieving health co-benefits from climate change mitigation policies.
• WHO monitors and reports on global trends and changes in health outcomes associated with actions taken to address air pollution at the national, regional, and global levels.
• WHO has developed and implemented a strategy to raise awareness of the risks of air pollution and the solutions available to mitigate these risks.

Other clean air initiatives include:

• The Clean Air Act, which has prompted the deployment of clean technologies and innovations that reduce emissions and control costs.
• The Clean Air Interstate Rule (CAIR), which has achieved large reductions in power plant annual SO2 and NOx emissions that contribute to fine particle pollution.
• The Clean Power Plan, which aims to reduce carbon pollution from power plants.
• The American Lung Association, which works to ensure that the air we breathe indoors and outdoors is clean and safe from harmful pollution.
• The Clean Air Fund, which works with governments, funders, businesses, and campaigners to deliver clean air for all as fast as possible.

Energy-efficient homes

The World Health Organization (WHO) defines indoor air pollution as contamination of the indoor environment by any chemical, physical, or biological agent that modifies the natural characteristics of the atmosphere. The use of polluting fuels and technologies in and around the home, such as kerosene lamps, biomass stoves, and coal, releases a range of health-damaging pollutants, including small particles that penetrate deep into the lungs and enter the bloodstream. This type of household air pollution is responsible for millions of deaths per year, with women and children bearing the greatest health burden.

To address this issue, WHO has developed guidelines for indoor air quality, offering practical evidence-based guidance on the use of clean fuels and technologies. These guidelines include recommendations such as discouraging the use of kerosene and unprocessed coal, specifying emission rate targets for fuels and technologies, and emphasizing the importance of addressing all household energy uses, particularly cooking, space heating, and lighting.

One way to improve indoor air quality and reduce energy consumption is to make energy-efficient upgrades to your home. Here are some ways to create an energy-efficient home with improved air quality:

• Improve Insulation: Increase insulation and reduce drafts to enhance temperature control. Proper insulation will help keep your home warmer in winter and cooler in summer, reducing the need for excessive heating or cooling systems.
• Moisture Control: Maintain adequate moisture control to prevent the growth of mould and mildew, commonly found in bathrooms and kitchens. You can achieve this by opening windows to promote ventilation or using a dehumidifier.
• Energy-Efficient Appliances: Invest in energy-efficient appliances, such as air-conditioning systems, heat recovery ventilators, and whole-house ventilation systems. These appliances can help mitigate the cost of heating and cooling your home while improving indoor air quality.
• Ventilation: Ensure proper ventilation in your home to reduce indoor air pollutants. Open windows, particularly at night when the outdoor air is cooler, to allow fresh air to flow through your home. If you live in an area with high outdoor pollution, carefully evaluate the use of ventilation and consider additional measures, such as air filtration systems.
• Air Filter Maintenance: Regularly clean or replace air filters in your AC systems, vacuum cleaners, clothes dryers, and kitchen vents. This will not only improve indoor air quality but also prolong the lifespan of your appliances.
• Natural Ventilation: Take advantage of natural ventilation by opening windows and doors to allow outdoor air to circulate indoors. This can help dilute indoor pollutants and improve air quality.
• Green Spaces: Support the development and preservation of green spaces, tree planting, and other cooling measures in your community. Urban areas with more vegetation tend to have lower temperatures due to the reduction of the Urban Heat Island effect.

By implementing these measures, you can create an energy-efficient home that improves indoor air quality and contributes to the reduction of climate change and its health impacts. Remember, even small changes can make a significant difference in creating a healthier and more sustainable living environment.

Health-based recommendations

Indoor air pollution is a serious issue, particularly in developing countries, where the burning of solid fuels like wood, coal, and dung releases harmful pollutants, including fine particulate matter and carbon monoxide. The World Health Organization (WHO) estimates that indoor air pollution causes approximately 3.8 million deaths annually, with women and children bearing the brunt of the health consequences.

• Ventilation: Proper ventilation is crucial for maintaining good indoor air quality. Ensure your home or workplace has adequate natural or mechanical ventilation systems in place. Natural ventilation can be achieved through opened windows and doors, while mechanical ventilation utilizes fans or air handling systems. Ventilation helps dilute indoor pollutants and carries them out of the indoor environment.
• Clean Fuels and Technologies: WHO recommends transitioning to cleaner fuels and technologies, such as solar, electricity, biogas, liquefied petroleum gas (LPG), natural gas, and alcohol fuels. These alternatives produce fewer emissions and are less harmful to health.
• Avoid Polluting Devices: Devices like kerosene lamps for lighting contribute to indoor air pollution and expose individuals to high levels of fine particulate matter. Access to electricity is essential to reducing the reliance on such polluting devices.
• Stove and Heating Alternatives: The use of open fires or inefficient stoves fueled by kerosene, biomass, or coal generates harmful household air pollution. Explore alternative cooking and heating methods that produce less pollution, such as electric stoves or solar-powered alternatives.
• Address Indoor Activities: Certain indoor activities, such as smoking, cleaning, painting, and cooking, can introduce pollutants into the air. Be mindful of these activities and try to minimize their impact. For example, opt for natural cleaning products or ensure proper ventilation during cooking.
• Building Materials and Furnishings: Building materials and furnishings can release pollutants. Choose materials that are less prone to off-gassing and opt for natural, non-toxic furnishings whenever possible.
• Air Quality Monitoring: Regularly monitor indoor air quality through air sampling, human exposure assessments, and computer modeling of airflow inside buildings. This monitoring can help identify potential sources of pollution and guide necessary interventions.
• Health Education and Awareness: Educate yourself and your community about the health risks associated with indoor air pollution. Understanding the signs and symptoms of exposure to indoor air pollutants can help prompt timely interventions and prevent long-term health consequences.
• Policy Interventions: Advocate for policies that promote clean energy, transport, housing, and urban development practices. Support initiatives that prioritize electrification, especially in developing countries, to reduce the reliance on polluting fuels and devices.
• Global and Regional Collaboration: WHO plays a crucial role in providing technical support and capacity building to countries and regions. Collaborate with organizations and governments to implement health-promoting household fuel and technology solutions, as well as raise awareness about the risks of indoor air pollution.

By following these health-based recommendations, we can significantly reduce the harmful impacts of indoor air pollution on human health and improve overall air quality, especially in vulnerable communities.

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