Air Pollution Limits: Impossible Standards, Unachievable Goals

The World Health Organization (WHO) has slashed its recommended limits for air pollution, urging nations to tackle dirty air and save millions of lives. The guideline limit for the most damaging pollution—tiny particles from burning fossil fuels—has been halved. The new limit for nitrogen dioxide (NO2), mainly produced by diesel engines, is now 75% lower. Almost 80% of the millions of deaths related to PM2.5 could be avoided if today’s pollution levels were reduced to those in the new guidelines, according to the WHO. However, scientists have stressed that even the new limits should not be considered safe, as there appears to be no level at which pollutants stop causing damage.

WHO air quality guidelines are evidence-based recommendations for limit values of specific air pollutants

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, and desert dust. 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 achieve air quality that protects public health. The first release of the guidelines was in 1987, and the latest global version was published in 2005. WHO updates the Air Quality Guidelines regularly to assure their continued relevance and to support a broad range of policy options for air quality management in various parts of the world. The guidelines are based on systematic literature reviews and subsequent rigorous evaluation methods, as well as extensive consultation with experts and end-users of the guidelines from all regions of the world.

The WHO Global Air Quality Guidelines (AQGs) provide recommendations on air quality guideline levels and interim targets for key air pollutants. They also offer qualitative statements on good practices for the management of certain types of particulate matter (PM), for example, black carbon/elemental carbon, ultrafine particles, and particles originating from sand and dust storms. The guidelines identify the levels of air quality necessary to protect public health worldwide and serve as a reference for assessing if and by how much the exposure of a population exceeds levels at which it might cause health concerns. The development of WHO guidelines adheres to a rigorous process of reviewing and evaluating evidence, and it involves several groups of experts with well-defined roles. A guideline development group defines the scope and key questions of the guidelines and develops the recommendations based on the distilled evidence provided by the systematic review team. An external review group provides valuable comments, while the WHO steering group, composed of WHO staff from all regions, oversees the implementation of the project.

The WHO Air Quality Guidelines recommend levels and interim targets for common air pollutants, including particulate matter (PM), ozone (O3), nitrogen dioxide (NO2), and sulfur dioxide (SO2). These guidelines are neither standards nor legally binding criteria, but they are designed to offer guidance in reducing the health impacts of air pollution based on expert evaluation of current scientific evidence. Guideline levels for specified pollutants can be used as an evidence-informed reference to help decision-makers in setting legally binding standards and goals for air quality management at international, national, and local levels. They are also a practical instrument for designing effective measures to achieve pollutant emission and concentration reductions and, therefore, to protect human health. The WHO periodically issues these health-based AQGs to assist governments and civil society in reducing human exposure to air pollution and its adverse effects.

The combined effects of ambient air pollution and household air pollution are associated with approximately 6.7 million premature deaths annually. Ambient outdoor air pollution is estimated to have caused 4.2 million premature deaths worldwide in 2019, with 89% of those premature deaths occurring in low- and middle-income countries. The greatest burden is found in the WHO South-East Asia and Western Pacific Regions. Air pollution is the greatest environmental threat to health and a leading cause of non-communicable diseases (NCDs) such as heart attacks or strokes. New research has also shown an association between prenatal exposure to high levels of air pollution and developmental delays at age three, as well as psychological and behavioural problems later on, including symptoms of attention deficit hyperactivity disorder (ADHD), anxiety, and depression.

The guidelines are developed through a transparent, evidence-based decision-making process

The World Health Organization's (WHO) Air Quality Guidelines (AQG) are developed through a transparent, evidence-based decision-making process. The guidelines are designed to help countries achieve air quality that protects public health, with regular updates to ensure their continued relevance and to support a broad range of policy options for air-quality management worldwide.

WHO rules and procedures for guidelines development involve the establishment of several expert groups, each with specific functions. One group selects the pollutants to be updated, such as particulate matter, ozone, nitrogen dioxide, and sulfur dioxide. Another group of experts drafts the background material, including literature reviews and assessments, which are then reviewed by the main group of experts. Based on this background material and associated comments, another Expert Group decides on the format and content of the updated guidelines and recommends changes to the supporting text.

The AQG provides global guidance on thresholds and limits for key air pollutants that pose health risks. These guidelines are of high methodological quality and are regularly updated to incorporate new health studies. The guidelines also offer interim targets to promote a gradual shift towards lower pollutant concentrations, which are associated with significant health benefits. For example, achieving interim target one (35 µg/m3) could save an estimated 300,000 lives worldwide each year.

WHO's AQG serves as a global target for national, regional, and city governments to improve the health of their citizens by reducing air pollution. Clean air is recognised as a basic human right, and air pollution is the greatest environmental threat to health, causing non-communicable diseases such as heart attacks and strokes. According to WHO data, 99% of the global population breathes air that exceeds guideline limits, with low- and middle-income countries suffering the highest exposures.

WHO promotes interventions and initiatives for healthy sectoral policies, addressing key risks from indoor and outdoor air pollution. It provides technical support to member states, offering authoritative advice on health issues related to air pollution and its sources. WHO also monitors and reports on global trends and changes in health outcomes associated with actions taken to address air pollution at various levels.

Air pollution is a complex mixture of solid particles, liquid droplets, and gases

The sources of air pollution are diverse and numerous, including household fuel burning, industrial chimneys, traffic exhausts, power generation, open burning of waste, agricultural practices, and desert dust. Different locations have varying compositions of particulate matter; for instance, an urban city by the sea may have particulate matter consisting of sea salt, road dust, and smoke from diesel engines, while a rural area near a forest may contain smoke from cookstoves and forest fires.

Particulate matter, often referred to as particle pollution, is a mix of tiny solid and liquid particles suspended in the air. These particles vary in size, shape, and chemical composition, and they can be harmful to human health. Some particles are large enough to be seen, such as dust, dirt, soot, or smoke, while others are so minuscule that they require an electron microscope for detection. The EPA defines particulate matter as "a mixture of mixtures," formed through mechanical and chemical processes.

Mechanical processes involve breaking down larger particles into smaller fragments, while chemical processes in the atmosphere create most of the fine and ultrafine particles. These particles can be emitted directly from sources such as construction sites, unpaved roads, fields, smokestacks, or fires. Additionally, they can form in the atmosphere through chemical reactions of gases, such as sulfur dioxide, nitrogen oxides, and certain organic compounds.

The WHO has established Air Quality Guidelines (AQG) to address air pollution and protect public health. These guidelines provide recommended limit values for specific air pollutants, including particulate matter, ozone, nitrogen dioxide, and sulfur dioxide. The AQG also offers interim targets to facilitate a gradual reduction in pollutant concentrations, aiming to improve health outcomes. Despite these guidelines, in 2019, 99% of the world's population lived in areas that did not meet the WHO air quality standards.

To reduce air pollution, various successful policies and interventions have been implemented. These include adopting clean technologies in industries, improving waste management practices, promoting access to clean household energy solutions, transitioning to cleaner modes of power generation and transportation, and incorporating renewable energy sources. By implementing these measures, we can strive towards cleaner air and improved health outcomes for people worldwide.

WHO promotes interventions and initiatives for healthy sectoral policies to address key health risks

Air pollution is a complex mixture of solid particles, liquid droplets, and gases. It is the greatest environmental threat to health and a leading cause of non-communicable diseases (NCDs) such as heart attacks, stroke, respiratory infections, and lung cancer. According to the World Health Organization (WHO), there are 7 million premature deaths every year due to the combined effects of outdoor and household air pollution. In 2019, 99% of the world’s population lived in places where the WHO air quality guidelines levels were not met.

WHO also provides recommendations for specific sectors to reduce air pollution. For industry, this includes implementing clean technologies to reduce smokestack emissions and improving waste management practices. In the energy sector, ensuring access to affordable clean household energy solutions for cooking, heating, and lighting is crucial. For transport, the focus is on shifting to clean modes of power generation, prioritizing sustainable urban mobility options, and adopting cleaner vehicles and fuels. Urban planning should aim for more energy-efficient buildings and greener, more compact cities. Power generation can be made cleaner by increasing the use of low-emissions fuels and renewable, combustion-free power sources.

Additionally, WHO promotes initiatives to address other key health risks. For example, immunization is one of the world's most successful and cost-effective health interventions. Universal health coverage (UHC) initiatives aim to ensure that everyone can access quality health services without financial hardship. WHO also supports the United Nations Sustainable Development Goals, which include commitments to end epidemics of AIDS, tuberculosis, malaria, and other communicable diseases by 2030, as well as achieving universal health coverage and access to safe and affordable medicines and vaccines.

Air pollution is the greatest environmental threat to health and a leading cause of non-communicable diseases

Air pollution is a complex mixture of solid particles, liquid droplets, and gases. It is caused by a variety of sources, including household fuel burning, industrial chimneys, traffic exhausts, power generation, open burning of waste, agricultural practices, and desert dust. According to the World Health Organization (WHO), air pollution is the greatest environmental threat to health. In 2019, 99% of the world's population lived in areas where WHO air quality guidelines were not met. The combined effects of ambient and household air pollution are associated with an estimated 6.7 million premature deaths annually. Outdoor air pollution alone caused 4.2 million premature deaths worldwide in 2019, with 89% of those deaths occurring in low- and middle-income countries.

The main pathway of exposure to air pollution is through the respiratory tract. Pollutants such as fine particulate matter, carbon monoxide, ozone, nitrogen dioxide, and sulfur dioxide can penetrate deep into the lungs, enter the bloodstream, and cause systemic damage to tissues and cells throughout the body. Short-term exposure to high levels of particulate matter can lead to reduced lung function, respiratory infections, and aggravated asthma. Long-term exposure increases the risk of non-communicable diseases such as stroke, heart disease, chronic obstructive pulmonary disease, and cancer. In addition, air pollution has been linked to adverse pregnancy outcomes, cognitive impairment, neurological diseases, and psychological and behavioural problems in children.

The 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 offer interim targets to promote a gradual shift towards lower pollutant concentrations, which can have significant health benefits. For example, achieving interim target one (35 µg/m3) could save 300,000 lives worldwide each year. The guidelines also provide recommendations for managing specific types of particulate matter, such as black carbon and ultrafine particles.

Addressing air pollution requires a combination of policy interventions and technological solutions. Successful policies include implementing clean technologies in industries, improving waste management practices, promoting access to clean household energy solutions, transitioning to cleaner modes of power generation and transportation, and improving the energy efficiency of buildings. Technological advancements, such as capturing methane gas emitted from waste sites and utilizing renewable combustion-free power sources, can also play a crucial role in reducing air pollution.

By implementing these measures and working towards the targets set by the WHO Air quality guidelines, governments and policymakers can improve air quality, reduce the health risks associated with air pollution, and protect the health and well-being of their citizens.

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