Air Standards: Who's Indoor Air Pollution Guidelines

The World Health Organization (WHO) has developed a set of guidelines for indoor air quality to protect public health from the adverse effects of indoor exposure to air pollution. These guidelines are intended for public health professionals and specialists involved in building design and the use of indoor materials and products. They provide recommendations for reducing exposure to common indoor air pollutants such as benzene, carbon monoxide, formaldehyde, and nitrogen dioxide, which can have detrimental effects on human health. While the guidelines are not legally binding, they serve as a global target for governments to improve air quality and protect the health of their citizens.

WHO guidelines for indoor air quality

The World Health Organization (WHO) has developed a set of Indoor Air Quality (IAQ) guidelines to protect public health from the adverse effects of indoor air pollution. These guidelines are based on scientific evidence and expert reviews, targeting hazardous substances commonly found indoors. The primary aim is to provide a uniform basis for safeguarding public health and minimizing exposure to harmful pollutants.

The WHO IAQ guidelines address specific pollutants known for their detrimental impact on human health. These include benzene, carbon monoxide, formaldehyde, naphthalene, nitrogen dioxide, polycyclic aromatic hydrocarbons (especially benzo[a]pyrene), radon, trichloroethylene, and tetrachloroethylene. These substances are chosen due to their indoor sources and the availability of toxicological and epidemiological data indicating health concerns.

For example, the WHO recommends an indoor nitrogen dioxide guideline of 200 μg/m3 for a one-hour exposure, consistent with its existing air quality guidelines. Studies show that asthmatics may experience pulmonary function decrements at twice this level. Additionally, an annual average indoor nitrogen dioxide guideline of 40 μg/m3 is advised, as an increase of 28 μg/m3 is associated with a 20% higher risk of lower respiratory illness in children.

The WHO's guidelines also consider the carcinogenicity of certain substances, such as trichloroethylene (TCE). The unit risk estimate of 4.3 × 10−7 (μg/m3) −1, based on increased testicular tumours in rats, is proposed as the indoor air quality guideline for TCE. However, for tetrachloroethylene, carcinogenicity is not selected as the endpoint due to equivocal epidemiological evidence and the irrelevance of animal tumour studies to humans.

The WHO's IAQ guidelines are intended to inform the development of national indoor air quality standards and provide guidance for public health professionals, specialists, and authorities involved in building design and the use of indoor materials and products. Poor IAQ has been linked to various health issues, including headaches, fatigue, and respiratory problems, emphasizing the importance of these guidelines in protecting public health.

Health risks of indoor air pollution

The World Health Organization (WHO) has issued guidelines for indoor air quality, specifically targeting public health professionals and specialists involved in building design and the use of indoor materials and products. These guidelines are based on scientific evidence and are designed to protect public health and the environment.

Indoor air pollution is a serious issue that can have significant health impacts. The sources of indoor air pollution are varied and include combustion sources such as tobacco smoke, wood and coal-burning appliances, and fireplaces, which can release harmful byproducts like carbon monoxide directly into the indoor environment. Other sources include cleaning supplies, paints, insecticides, and building materials such as asbestos or pressed wood products that emit chemical off-gassing.

The health risks associated with indoor air pollution are diverse and range from immediate to long-term effects. Some common symptoms include irritation of the eyes, nose, and throat, headaches, dizziness, and fatigue. More severe consequences include respiratory diseases, heart disease, and cancer. Fine particulate matter (PM2.5) found in indoor air pollution can penetrate the lungs and enter the bloodstream, affecting major organs and leading to cardiovascular and respiratory issues, including stroke, lung cancer, and chronic obstructive pulmonary disease (COPD).

Additionally, indoor air pollution has been linked to developmental delays in children, with prenatal exposure associated with psychological and behavioural problems, including symptoms of ADHD, anxiety, and depression. The impact of indoor air quality on vulnerable individuals, such as the very young, older adults, or those with existing cardiovascular or respiratory conditions, can be particularly pronounced.

It is important to note that indoor concentrations of pollutants can be significantly higher than outdoor levels due to inadequate ventilation and the use of synthetic building materials and household products. The lack of access to clean fuels and technologies, such as electricity, further exacerbates the problem, especially in developing countries. Therefore, addressing indoor air pollution through improved ventilation, the use of cleaner fuels, and the implementation of health-based guidelines is crucial to mitigate the adverse health effects on those exposed.

Reducing indoor exposure to pollutants

The World Health Organization (WHO) has developed Air Quality Guidelines (AQG) to help countries improve air quality and protect public health. These guidelines are not legally binding, but they serve as a global target for governments to work towards reducing air pollution and improving the health of their citizens.

Indoor air pollution is a serious issue that can negatively impact human health. It is caused by various sources, including household fuel burning, secondhand tobacco smoke, cooking stoves, and the release of chemicals from consumer products, gas appliances, and building materials. To reduce exposure to indoor pollutants, it is important to take the following measures:

Ventilation

One of the most effective ways to improve indoor air quality is to ensure proper ventilation. Opening windows and doors can help increase air movement and reduce the buildup of pollutants. In addition, mechanical systems such as energy-efficient heat recovery ventilators can be used to bring outdoor air into the home, improving indoor air quality.

Source Control

Eliminating or reducing individual sources of pollution is crucial. This can include sealing or enclosing materials that contain asbestos, adjusting gas stoves to decrease emissions, and avoiding the use of hibachis, charcoal grills, unvented space heaters, or portable generators indoors. It is also important to avoid using high-emitting products, such as paint, glue, and incense, indoors. If possible, use these products outdoors or increase ventilation when using them indoors.

Air Cleaners

While the effectiveness of air cleaners in reducing radon levels is uncertain, using one or more high-efficiency portable air cleaners certified by CARB can help remove airborne particles. However, it is important to ensure that the air cleaner does not emit ozone.

Choosing Safer Products

When purchasing building materials, furnishings, and consumer products, choose safer and environmentally friendly options. Look for labels that indicate compliance with California Phase II or TSCA Title VI for composite wood products. For carpet, cushion, and adhesive products, opt for those with the Carpet and Rug Institute (CRI) Green Label Plus logo. Consider using formaldehyde-free products, such as solid wood, gypsum board, and stainless steel, whenever possible.

Regular Maintenance

Have gas heaters and stoves checked annually by a professional to ensure they are functioning properly and are vented to the outdoors. This will help prevent the buildup of carbon monoxide and other air pollutants.

By following these measures, individuals can significantly reduce their exposure to indoor pollutants and improve their overall health and well-being.

Improving indoor air quality

The World Health Organization's Air Quality Guidelines (AQG) are a set of evidence-based recommendations for limit values of specific air pollutants. The guidelines are designed to help countries improve air quality and protect public health. According to the WHO, air pollution is the greatest environmental threat to health and is a leading cause of non-communicable diseases such as heart attacks, stroke, lung cancer, and chronic obstructive pulmonary disease (COPD).

To improve indoor air quality, it is important to address the sources of pollution and reduce their emissions. This can be done by sealing or enclosing certain sources, such as those containing asbestos, or adjusting others, like gas stoves, to decrease emissions. Increasing ventilation and natural shading can also help control indoor temperatures and reduce pollutants. Mechanical means, such as outdoor air intakes associated with HVAC systems, can also be used to bring in outdoor air. However, it is important to carefully evaluate the use of ventilation when there are outdoor sources of pollution, such as smoke, nearby.

Air cleaners and filtration devices can be effective in improving indoor air quality, but their effectiveness depends on their ability to collect pollutants and the amount of air they draw through. Regular maintenance and following the manufacturer's directions are crucial for the long-term performance of these devices. Table-top air cleaners may not be sufficient for strong nearby sources of pollution.

To reduce the impact of indoor air pollution on asthma and allergies, it is recommended to avoid strong scents, such as perfumes and essential oils, and use only approved, unscented, and low-VOC cleaning products. Keeping humidity between 30% and 50% can help prevent dust mites and mould growth. Additionally, it is important to fix leaks immediately to prevent mould and avoid the use of air cleaners that release harmful levels of ozone.

Overall, improving indoor air quality requires a combination of source control, ventilation, the use of air cleaners, and the adoption of practices that reduce emissions and pollutants.

The impact of indoor air pollution on vulnerable groups

Indoor air pollution is a serious issue that disproportionately affects vulnerable groups, including women, children, and individuals in low- and middle-income countries. The World Health Organization (WHO) recognizes the urgency of addressing the health impacts of air pollution and has developed guidelines for indoor air quality to protect public health.

One of the primary sources of indoor air pollution is the use of inefficient and polluting fuels and technologies in households. This includes the burning of household fuel, such as kerosene and unprocessed coal, for cooking, space heating, and lighting. In poorly ventilated dwellings, the levels of fine particles from indoor smoke can reach concentrations 100 times higher than acceptable levels. Women and children, who typically spend the most time near the domestic hearth, are at particularly high risk of exposure to these harmful pollutants.

The health consequences of indoor air pollution are significant. Fine particulate matter (PM2.5) can penetrate the lungs and enter the bloodstream, affecting major organs. Exposure to PM2.5 has been linked to cardiovascular and respiratory diseases, including stroke, lung cancer, and chronic obstructive pulmonary disease (COPD). Additionally, research has found an association between prenatal exposure to high levels of indoor air pollution and developmental delays, as well as psychological and behavioural issues later in life, such as symptoms of ADHD, anxiety, and depression.

The impact of indoor air pollution extends beyond physical health. In households relying on polluting fuels and technologies, women bear a disproportionate burden due to the additional time spent on cooking, gathering fuel, and preparing fuel for inefficient stoves. This unequal distribution of labour can contribute to time poverty and further exacerbate gender inequalities.

Furthermore, indoor air pollution disproportionately affects individuals in low- and middle-income countries. According to WHO, 89% of premature deaths attributed to combined ambient and household air pollution occur in these regions. Socio-economic factors, such as building characteristics (build quality, volume, and ventilation) and occupant behaviour, play a significant role in determining indoor air quality. Disparities in indoor air pollution exposure across socio-economic groups can lead to health inequalities, underscoring the need for targeted interventions and policies.

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