Air Quality Guidelines: Who's Take On Healthy Air

Air pollution is a serious issue that affects people worldwide. It is caused by a complex mixture of solid particles, liquid droplets, and gases, which can come from various sources, such as household fuel burning, industrial chimneys, traffic exhausts, and agricultural practices. The World Health Organization (WHO) has developed Air Quality Guidelines (AQGs) to help countries achieve better air quality and protect public health. These guidelines are based on scientific evidence and expert evaluations and provide recommended limit values for specific air pollutants. While they are not legally binding, they offer essential guidance for reducing the health impacts of air pollution, which has been linked to cardiovascular and respiratory diseases, premature deaths, and other adverse effects on health and quality of life.

Air pollution sources

Air pollution is a complex mixture of solid particles, liquid droplets, and gases. It can come from many sources, including household fuel burning, industrial chimneys, traffic exhausts, power generation, open burning of waste, agricultural practices, desert dust, and many other sources.

Different sources can lead to different mixtures of air pollution. For example, an urban city near the sea can have particulate matter consisting of sea salt, road dust, and smoke from diesel engines. In contrast, a rural area near a forest may have particulate matter consisting of soil, smoke from cookstoves, and forest fires.

Particulate matter (PM) is primarily generated by fuel combustion in different sectors, including transport, energy, households, industry, and agriculture. In 2013, outdoor air pollution and particulate matter were classified as carcinogenic by the WHO's International Agency for Research on Cancer (IARC). Exposure to air pollution, second-hand smoke, radon, ultraviolet radiation, asbestos, certain chemicals, and other pollutants cause over 10% of all cancer cases in Europe, according to a European Environment Agency (EEA) report.

The sources of outdoor air pollution can be reduced by policies and investments supporting cleaner transport, energy-efficient homes, power generation, industry, and better municipal waste management. Access to clean household energy would also greatly reduce ambient air pollution in some regions.

Air pollution and health

Air pollution is a serious threat to health and climate. It is caused by a complex mixture of gases, solid particles, and liquid droplets in the air. Common sources of air pollution include household combustion devices, motor vehicles, industrial facilities, forest fires, residential energy for cooking and heating, power generation, agriculture, and waste incineration.

The World Health Organization (WHO) has developed global air quality guidelines (AQG) to provide guidance on thresholds and limits for key air pollutants that pose health risks. These guidelines are based on systematic literature reviews, rigorous evaluation methods, and consultations with experts and end-users from all regions of the world. The AQG offers qualitative statements on good practices for managing certain types of particulate matter and provides interim targets to promote a gradual shift towards lower concentrations of pollutants, thereby reducing health risks.

The health effects of air pollution can be seen in both children and adults and can occur due to short-term and long-term exposure to air pollutants. The main pathway of exposure is through the respiratory tract, which can lead to inflammation, oxidative stress, immunosuppression, and mutagenicity in cells throughout the body. Fine particulate matter poses a significant health risk as these very small particles can penetrate deep into the lungs, enter the bloodstream, and cause systemic damage to tissues and cells. Exposure to high levels of particulate matter can lead to reduced lung function, respiratory infections, and aggravated asthma from short-term exposure. Long-term or chronic exposure to fine particulate matter increases the risk of non-communicable diseases such as stroke, heart disease, chronic obstructive pulmonary disease, and cancer.

Maternal exposure to air pollution is associated with adverse birth outcomes, such as low birth weight, pre-term birth, and small gestational age births. There is also suggestive evidence linking air pollution exposure with an increased risk of other cancers, diabetes, cognitive impairment, and neurological diseases. Overall, air pollution is estimated to cause millions of premature deaths worldwide each year, with the burden disproportionately affecting people in low- and middle-income countries.

To address the health impacts of air pollution, the WHO provides technical support to its member states, helping them develop normative guidance, tools, and authoritative advice on health issues related to air pollution. The organization also promotes interventions and initiatives for healthy sectoral policies, including energy, transport, housing, and urban development. Additionally, the WHO has implemented strategies to raise awareness about the risks of air pollution and the available solutions to mitigate exposure.

Air quality management policies

Air pollution is a complex mixture of solid particles, liquid droplets, and gases, arising from sources such as household fuel burning, industrial chimneys, traffic exhausts, power generation, open burning of waste, agricultural practices, and many other sources. The World Health Organization (WHO) has developed Air Quality Guidelines, a set of evidence-based recommendations of limit values for specific air pollutants, to help countries achieve air quality that protects public health. These guidelines are based on systematic literature reviews, rigorous evaluation methods, and extensive consultation with experts and end-users from all regions of the world. They are updated regularly to account for new health studies and the evolving nature of air pollution.

The WHO Air Quality Guidelines are neither standards nor legally binding criteria. Instead, they offer guidance to countries on reducing the health impacts of air pollution. The guidelines incorporate scientific evidence from multiple countries, making them adaptable to diverse conditions and supporting a broad range of policy options for air quality management. They recommend levels and interim targets for common air pollutants, including particulate matter (PM2.5 and PM10), ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide.

The guidelines are designed to be flexible, allowing governments to adapt them based on their technical capabilities, economic capacity, existing air quality management policies, and other political and social factors. For example, the UK's Local Air Quality Management (LAQM) regime is designed to protect people's health from the adverse effects of air pollution. However, it has been criticized for its limited integration of public health aspects, ineffective communication, and disconnected policies. Greater integration of public health in LAQM future design and delivery can help improve risk assessments, raise awareness, target actions in high-need areas, and coordinate interventions.

Additionally, the Comprehensive and Systematic Analysis (CECA) framework offers a comprehensive analysis of a city's capacity to formulate and implement air quality management strategies. It comprises 31 indicators across nine dimensions and three main components: technical capabilities, data capabilities, and exploiting capabilities. The application of CECA in Latin American cities, notably Mexico City and Santiago, has led to strengthened institutions and policies, demonstrating the effectiveness of integrating technical knowledge into long-term AQM plans.

Reducing air pollution exposure

Air pollution is a serious global public health problem that demands action from both governments and individuals. According to the World Health Organization (WHO), air pollution is a complex mixture of solid particles, liquid droplets, and gases that can come from various sources, including household fuel burning, industrial chimneys, traffic exhausts, power generation, open burning of waste, agricultural practices, and many other sources.

The WHO has developed Air Quality Guidelines, which are evidence-based recommendations of limit values for specific air pollutants. These guidelines are designed to help countries achieve air quality that protects public health and reduce the health impacts of air pollution. While the guidelines are not legally binding, they are based on rigorous evaluations and consultations with experts from all regions of the world. The guidelines recommend levels and interim targets for common air pollutants such as particulate matter (PM), ozone (O3), nitrogen dioxide (NO2), and sulfur dioxide (SO2).

To reduce air pollution exposure, collective action is required to control emissions of primary air pollutants and precursors that form secondary air pollutants. This includes implementing policies and investments that support cleaner transport, energy-efficient homes, clean power generation, improved industrial and municipal waste management, and better agricultural practices. For example, providing access to clean household energy solutions for cooking, heating, and lighting can significantly reduce ambient air pollution in some regions. Additionally, promoting active transport, such as walking and cycling networks in cities, and the use of low-emission vehicles and fuels can also help reduce air pollution.

At the individual level, there are also actions that can be taken to reduce exposure to air pollution. On days with high air pollution levels, staying indoors, reducing outdoor air infiltration into homes, using air filters to clean indoor air, and limiting physical exertion, especially outdoors and near pollution sources, can help minimize exposure. It is important for individuals with chronic cardiovascular or pulmonary disease, children, and the elderly to be particularly aware of air pollution levels and take precautions to avoid exposure. While individual actions can provide some protection, they are not as effective as societal actions to reduce emissions at their sources.

Air quality targets

Air pollution is a complex mixture of solid particles, liquid droplets, and gases, which can come from many sources, including household fuel burning, industrial chimneys, traffic exhausts, power generation, open burning of waste, agricultural practices, and desert dust. The World Health Organization (WHO) has identified air pollution as the largest environmental health risk in Europe, causing cardiovascular and respiratory diseases that impact health, reduce quality of life, and cause preventable deaths.

WHO's Air Quality Guidelines (AQGs) are a set of evidence-based recommendations of limit values for specific air pollutants. The guidelines are designed to help countries achieve air quality that protects public health. They are based on systematic literature reviews, rigorous evaluation methods, and extensive consultation with experts and end-users of the guidelines from all regions of the world. While the guidelines are not legally binding, they are intended to influence air quality policies and support a broad range of policy options for air quality management.

The AQGs recommend levels and interim targets for common air pollutants, including particulate matter (PM2.5 and PM10), ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO). For example, the 2021 guidelines recommend annual mean concentrations of PM2.5 not exceeding 5 µg/m3 and NO2 not exceeding 10 µg/m3, which is a significant reduction from the 2005 guideline values of 10 µg/m3 for PM2.5 and 40 µg/m3 for NO2.

WHO updates the AQGs regularly to ensure their continued relevance and to address the real and continued threat of air pollution to public health. The guidelines are designed to be used in diverse conditions in all WHO regions and to support a wide range of policy options for air quality management. Governments across the world can use the guidelines to develop and implement bold air quality actions at the international, national, and local levels and across various sectors, including transport, energy, industry, agriculture, and residential.

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