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Frequently Asked Questions on Air Pollution

Photo by Ryoji Iwata on Unsplash

The theme of this year’s International Day of Clean Air for blue skies is Racing for Air, reflecting that air pollution does not recognize borders and slows everyone down. It is a global crisis that requires collective action from governments, businesses, and individuals.

Here, we have 24 Frequently Asked Questions about air pollution and how to improve air quality from different perspectives, answered by scientists from all over the world.

1. CAN ADDRESSING AIR POLLUTION ACCELERATE SUSTAINABLE DEVELOPMENT?

Addressing air pollution can be a powerful accelerator of sustainable development because it delivers simultaneous benefits across health, climate, and equity. Reducing air pollution improves public health by lowering the incidence of respiratory and cardiovascular diseases, which in turn reduces healthcare costs and increases productivity. Many of the solutions to air pollution—such as the promotion of clean energy or clean cooking—also contribute to good health and food security. Cleaner air also contributes to climate action, as some air pollutants—such as black carbon and ozone—are also short-lived climate pollutants. The actions to reduce air pollutant emissions from transport, energy, agriculture, and industry often promote cleaner technologies, sustainable urban planning, and green jobs.

These co-benefits support multiple Sustainable Development Goals (SDGs). More concretely, SDG 3 on health, SDG 11 on cities, and SDG 12 on sustainable consumption and production, which includes waste management, include targets referring to air pollution. There are also three indicators related to air pollution under the above three targets (See Question 25 for more details). Other SDGs address solutions to air pollution, such as energy efficiency and renewable energy in SDG 7 and sustainable transport in SDG 11. Similarly, some SDGs will benefit from less air pollution, such as SDG 2 on food security and SDG 3 on health; and pursuing some other SDGs (such as SDG 15 on combating desertification) is also a way to reduce air pollution. While air pollution is covered in some SDG targets and indicators, there is no standalone headline goal on air pollution. This may have resulted in less attention to air pollution in global policy discussions and less development financing, since development assistance is often aligned with the SDGs. Air pollution is also rarely mentioned in countries’ Voluntary National Reviews (VNRs) reporting their progress on the SDGs. Recognizing the urgent need for bold action, in 2024, world leaders united under the Pact of the Future, pledging to urgently accelerate progress towards the Sustainable Development Goals, including efforts to address the pollution of air.

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2. GLOBAL AND REGIONAL ACTIONS ON AIR QUALITY

Why is international cooperation important for addressing air pollution, and what steps has the UN taken to support it?

Since air pollutants can travel long distances and across borders, regional and international cooperation is essential to effectively address air pollution. Cross-border collaboration enables countries to share knowledge, align strategies, and mobilize the resources needed to tackle air pollution at scale.

Recognizing this, countries at the sixth session of the UN Environment Assembly (UNEA-6) adopted a resolution on March 1, 2024, titled Promoting regional cooperation on air pollution to improve air quality globally. The resolution calls for stronger collaboration across governments, health and environmental organizations, and the private sector to address air pollution’s wide-ranging impacts, in line with the Sustainable Development Goals.

It highlights the multiple benefits of addressing air pollution, including improving human health, the economy, ecosystems, and the climate, and encourages Member States to accelerate the development of national air quality programmes and standards aligned with WHO guidelines.

To support this effort, the resolution requested the UN Environment Programme (UNEP), subject to the availability of resources, to form and facilitate a cooperation network on air quality. The new Global Air Quality Cooperation Network will empower governments at different levels and other key stakeholders to reduce air pollution through enhancing air quality management capacities, increasing the uptake of solutions to reduce air pollution from high-impact sectors, and improving access to finance, funding, and other forms of support. UNEP convened the first meeting of the Network on 24th March 2025, on the margins of the WHO’s Second Global Conference on Air Pollution and Health, held in Cartagena, Colombia.

As part of the UN agencies, the World Health Organization has taken concrete steps to foster international cooperation for air quality and better health. In March 2025, WHO and the Government of Colombia co-hosted the Second Global Conference on Air Pollution and Health in Cartagena. The event gathered over 700 participants from 100 countries, governments, UN agencies, civil society, scientists, and health professionals, to accelerate action. Over 50 new clean air commitments from governments, cities, and organizations, were launched at the conference alongside a powerful call to action supported by nearly 50 million health workers, patients, and civil society group representatives. A major outcome was the agreement on a global voluntary target to halve the health impacts of air pollution by 2040. This shared goal has been officially endorsed by Member States at the 78th World Health Assembly through the adoption of an updated WHO roadmap on air quality. 

The UNEA resolution also requested UNEP, subject to the availability of resources, to support the development of an Africa Clean Air Programme (further discussed below) and to provide an updated global online platform for information sharing and communication.

In response, a dedicated online knowledge platform was launched by the UNEP-convened Climate and Clean Air Coalition in 2024. The Air Quality Management Exchange Platform (AQMx.org) is conceived as a ‘one stop shop’ for technical tools and models, data, and knowledge to build capacity among air quality managers worldwide. The platform provides curated guidance across eight core areas of air quality management and hosts a resource exchange library featuring over 900 vetted resources and knowledge products, periodically updated as new resources are published.

For more information see here:

 

What international and regional agreements exist to reduce air pollution, and how do they support cooperation?

Every world region is part of at least one multinational agreement to reduce air pollution. The earliest and most established of these is the Convention on Long-range Transboundary Air Pollution (CLRTAP), established in 1979 by 32 UNECE countries. CLRTAP entered into force in 1983 and was the first coordinated international effort to jointly address shared air pollution. Today it includes 51 Parties, 8 active protocols, and serves as a global model for science-policy cooperation on air quality.

CLRTAP is unique as a legally binding agreement which sets emission reduction targets for several pollutants. It provides a platform for countries to discuss policies and to exchange best practices. The Convention counts on a solid science-policy interface, a compliance mechanism, and a capacity-building support programme. To share lessons more broadly, the Convention recently launched the Forum for International Cooperation on Air Pollution (FICAP), which promotes global collaboration and learning.

Other regions have also developed mechanisms to address transboundary air pollution:

3. WHY IS IT SO IMPORTANT TO REDUCE AIR POLLUTION?

Air pollution is all around us. Most people in the world live in areas with high levels of air pollution. It harms human health and wellbeing, reduces quality of life, and can negatively impact the economy and ecosystems. These impacts also disproportionately affect the most vulnerable people and communities.

Air pollution is the largest environmental risk to public health globally. People everywhere are exposed to air pollution: in the workplace, during travel, and in their homes. Exposure to the combined effect of household and ambient (outdoor) fine particulate matter air pollution causes an estimated 6.7 million premature deaths each year, according to the World Health Organization (WHO), and is responsible for a substantial amount of disability for those living with diseases caused by air pollution. The 2024 State of Global Air estimated that air pollution accounted for 8.1 million deaths globally in 2021.

Air pollution is also a transboundary issue; it does not stop at administrative or country borders but affects air quality and ecosystems beyond its source (see more on question 10). Addressing it requires coordinated action from governments and communities.

In many developing countries, reliance on solid fuels (like biomass and coal for cooking and heating, and the use of kerosene for lighting) increases air pollution in homes, harming the health of those exposed. WHO estimates that more than 2.3 billion people rely on these types of fuels. Most of these effects are felt in parts of Asia and sub-Saharan Africa, where burning biomass for cooking is especially prevalent.

While the impacts on human health are the most pressing, air pollution also significantly impacts ecosystems, agriculture, and infrastructure. For example, ozone pollution has been seen to affect plant diversity due to effects on ozone-sensitive plant species, which reduce in abundance, and also the reductions in the yield of different crops and trees. It also reduces atmospheric visibility and increases corrosion of materials, buildings, monuments, and cultural heritage sites, and causes acidification of sensitive soils and lake ecosystems, causing losses of fish populations.

Air pollution also has high economic costs related to human health, lost productivity, reduced crop yields, and reduced competitiveness of globally connected cities. For example, a 2021 World Bank study found that the economic cost of the health impacts of air pollution alone totalled US$8.1 trillion in 2019, equivalent to 6.1 percent of global Gross Domestic Product (GDP) (see more on questions 11, 12, and 13).

Air pollution is strongly linked to climate change, sharing many of the same sources. Many air pollutants are both bad for human health and disruptive to the Earth's ecosystems impacting people’s lives today and future generations. This has given rise to coordinated measures to reduce air pollution and GHGs, such as those addressing Short-Lived Climate Pollutants (SLCPs) (see more on question 24). Higher temperatures can also increase the volatilization of some pollutants, such as Persistent Organic Pollutants (POPs) that are already in the environment, causing additional exposure to these pollutants.

Reducing air pollution is tied to the achievement of the Sustainable Development Goals (SDGs) (see question 3), and directly affects the achievement of SDG 2: Zero Hunger, SDG 3: Good Health and Wellbeing, SDG 7: Affordable and Clean Energy, SDG 11: Sustainable Cities and Communities, and SDG 13: Climate Change. It indirectly impacts the achievement of many other SDGs (see more on questions 3 and 25).

From past and current experience, we know that much of human-caused air pollution is preventable, and as the examples show, reducing air pollution will provide additional benefits like healthier and more productive lives, a healthier natural environment, poverty alleviation and increased shared prosperity.

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4. WHAT IS AIR POLLUTION?

Air pollution is caused by gases and particles emitted to the atmosphere from a variety of human activities, such as the inefficient combustion of fuels or the open burning of waste, agriculture, and farming. There are also natural sources contributing to air pollution, many of which are impacted by human activities such as forest fires, soil dust, and salt in sea spray.

Air pollutants can be emitted directly from a source (i.e., primary pollutants) or can form from chemical reactions in the atmosphere (i.e., secondary pollutants). When concentrations of these substances reach critical levels in the air, they harm humans, animals, plants and ecosystems, reduce visibility and corrode materials, buildings and cultural heritage sites. Even at relatively low levels, some pollutants—such as PM2.5—can still have negative health effects.

The main pollutants affecting human health are particulate matter, ground-level ozone (O3), and nitrogen dioxide  (NO2), sulphur dioxide  (SO2), ammonia (NH3), volatile organic compounds  (VOCs), and carbon monoxide (CO). The fine particles that damage human health are known as PM2.5 (particles with a diameter of less than 2.5 micrometres), which can penetrate deep into the lungs and pass into the bloodstream, affecting different organs and bodily functions. These particles can either be emitted directly (e.g., black carbon, organic carbon, mineral particles, brake dust, and tire wear) or formed in the atmosphere from several different emitted pollutants (e.g. SO2, Nitrogen oxides (NOX), NH3, and VOCs).

Ozone (O₃) is an important secondary pollutant. It is a strong irritant to the human lungs and stunts the growth and yield of plants., including important crops and trees. It is also a powerful greenhouse gas (GHG). O₃ is formed in the troposphere, near the Earth’s surface, when certain precursor pollutants (NOX, non-methane VOCs, methane, CO) react in the presence of sunlight. The powerful GHG methane (CH₄), is responsible for a significant portion of O₃ formation. This tropospheric ozone is different from the ozone in the upper atmosphere (stratosphere), which protects us from ultraviolet light from the sun.

Nitrogen oxides (NOX) are a group of air polluting chemical compounds, comprising nitrogen dioxide (NO2) and nitrogen monoxide (NO). NO2 is the most harmful of these compounds for human health and is generated from human activities. It impacts human health, reduces atmospheric visibility, and can play a significant role in climate change, at high concentrations. Finally, it is a critical precursor to the formation of O₃ and fine particulates (PM2.5).

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5. HOW LONG HAS AIR POLLUTION BEEN A PROBLEM?

Air pollution has been associated with humans for millennia, starting with the use of fire for cooking and warmth. Dangerously high levels of outdoor air pollution became a problem during the industrial revolution, where the massive use of coal gave rise to many episodes of serious urban air pollution.

The case of the London Smog Disaster of 1952, is an extreme example, causing a surge in deaths over a one-week episode. The pollution from residential coal fires, coal for electricity generation, dirty transport fuels, and industrial pollution interacted with weather phenomena which trapped the pollution over London and led to over 4,000 excess deaths over just a few days and estimates of up to 12,000 in the following few weeks. The public outcry that followed led to the adoption of the UK Clean Air Act (1956). Other fatal air pollution episodes, like in Donora, USA (1948), and Meuse Valley, Belgium (1930), prompted similar actions to be taken to tackle air pollution in other countries.

Continued reliance on fossil fuels through the 20th century saw air pollution increase as countries industrialized. In newly industrialised countries like China and India, this has led to extreme air pollution events, like those experienced in the past in the USA and Europe. However, new forms of cleaner and renewable energy, and the adoption of air quality regulations and management processes, are reducing reliance on some polluting fuels and practices.

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6. WHERE DOES AIR POLLUTION COME FROM?

Air pollution comes from both outdoor and indoor sources and can be either natural or human-caused (anthropogenic). Outdoor burning of fossil fuels for transport (like vehicles, shipping and aviation); industrial and power plants and waste burning are among the most significant anthropogenic sources of air pollution globally. Agriculture and livelihood activities also play an important role.

Biomass burning, such as forest fires and wildfires is another major source of air pollution. While wildfires are sometimes classified as natural sources of air pollution, their frequency and intensity are increasing due to human-driven climate change, and they are sometimes lit deliberately (see Question 9). In some regions and seasons, residential fuel use for cooking and heating also contributes significantly to outdoor air pollution.

Many of these sources, especially fossil fuel combustion, not only pollute the air but also contribute to global warming.

Natural sources of air pollution include volcanic eruptions, sea spray, soil and desert dust, natural vegetation fires, and lightning. However, some of these sources, such as forest and savanna fires and windblown mineral dust, are worsened by human activities.

In cities, air pollution comes from both within and beyond city boundaries, with some pollutants travelling over long distances. Major urban sources include vehicles, burning of gas, coal and charcoal, wood for cooking and heating, and industrial sources located in cities. Many large industrial sources, such as cement plants, steel plants and electricity generation, oil and gas production and refining, and maritime sources are often located away from cities, but still contribute a lot to the urban air pollution through long distance transport in the air.

Agricultural sources, including burning to clear land, and forest fires, contribute a lot to urban and rural air pollution levels. Most ammonia is emitted from agriculture and human waste treatment and can lead to PM2.5 formation. In very dry areas, close to deserts and eroded land, wind-blown dust can make up a large fraction of the PM2.5.

One of the most common sources of air pollution in rural and peri-urban areas of low- and middle-income countries comes from households burning biomass, other solid fuels like coal, or kerosene for cooking, heating, and lighting, all of which contribute to indoor air pollution. Household air pollution also contributes to outdoor air pollution.

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7. HOW DO WILDFIRES CONTRIBUTE TO AIR POLLUTION?

Smoke from wildfires as well as other landscape fires used for land clearing and agriculture are a major contributor to air pollution, contributing to roughly 4% of global PM2.5. A 2021 report of the Lancet Countdown shows that between 2017–2020, nearly 60% of countries saw more days classified as having “very high” or “extremely high” fire danger compared to 2001–2004, while 72.4% experienced increased wildfire exposure. The rise was more pronounced in low Human Development Index (HDI) countries, with 83% affected, compared to 62.5% of very high HDI countries. Extreme fire smoke events can lead to very high levels of air pollution over a one-to-two-week periods, easily the highest levels experienced throughout the year in affected locations.

The year of 2024 saw devastating and record-breaking wildfires across the globe, including South America, Greece, Spain, Portugal, Turkey and other parts of Europe, Canada, the western United States, and large parts of eastern Russia.

In 2024, an unprecedented series of wildfires significantly impacted across South America, significantly impacting countries such as Bolivia, Brazil, Chile, Colombia, Ecuador, and Peru. According to the Global wildfire Information System (GWIS), around 85 million hectares of land were burned. The wildfires led to massive deforestation of the Amazon rainforest, and they also impacted several other international biomes including the Pantanal wetlands. They have also resulted in hazardous air quality in parts of Bolivia and Brazil for more than 150 days. Smoke spread across the continent, leading to risks of worsening respiratory disease. These fires have destroyed homes, resulted in livestock losses, and caused the displacement of hundreds of residents.

The cumulative health impacts of repeated exposure to annual smoke episodes are still unclear, but evidence from general air pollution research suggests this is likely. A 2012 analysis estimated that smoke from landscape fires accounts for approximately 10% of all annual deaths attributable to particulate matter (PM) air pollution worldwide. In the US, several studies have estimated that gains made towards clean air are being lost due to frequent wildfire events, with increased premature deaths per year from 2000 to 2020.

As wildfire smoke events are expected to increase with a warming climate and are more difficult to control at the sources than other common air pollution sources, adaptation strategies are essential. Communities in wildfire-prone areas should establish clean-air shelters, while individuals, especially the most vulnerable, can reduce exposure by using HEPA filter portable air cleaners and ensuring they have an adequate supply of medications to last through extended wildfire seasons.

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8. IS AIR POLLUTION MAINLY A LOCAL PROBLEM OR CAN IT TRAVEL LONG DISTANCES?

Air pollution has no boundaries. Air pollution significantly impacts places near its source, but because it can be carried long distances in the atmosphere, air pollution can also affect faraway places. For example, pollutants that form into fine particulate matter (PM2.5), persistent organic pollutants (POPs), and ozone (O3) can travel over hundreds or thousands of kilometres, causing regional and continental impacts. This transboundary air pollution leads to challenges for regulations and enforcement because different countries or regions, have little regulatory control over air pollution coming from outside their borders (also see question 14).

Despite the contribution of long-distance air pollutants to local air pollution, nearby sources remain a very significant determining factor of local air quality. Pollutants like nitrogen dioxide (NO2) and sulphur dioxide (SO2) have concentration levels which are highest close to their sources (transport, energy production, and industries). Within a city, areas closest to large sources can have huge pollutant concentrations, while other areas of the same city can be much cleaner.

Atmospheric conditions, such as wind, affect pollutant dispersion and can vary widely. Strong winds enable long-distance transport, and stagnant conditions can lead to a build-up of pollutants. Large cities in subtropical and tropical regions that have very light winds and many hours of sunshine experience serious pollution episodes. Mountains surrounding cities, land-sea breezes, and other local weather conditions can affect the spread of pollutants and influence the formation of secondary pollutants.

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9. HOW DOES AIR POLLUTION AFFECT HUMAN HEALTH?

The air pollutant of greatest concern for human health, and that we know most about, is fine particulate matter. This has a diameter of 2.5 micrometres or less, which is why it is also known as PM2.5. These fine particles are invisible to the human eye and 40 times smaller than the width of a human hair. They can do a lot of damage to our bodies: these particles are small enough to penetrate deep into our lungs, where they cause inflammation of sensitive lung tissue and can pass into the bloodstream, affecting organs like the heart and brain. The WHO estimates that, globally, the combination of outdoor and indoor air pollution are responsible for about 6.7 million premature deaths per year.

Air pollution causes both acute disease and chronic disease. There is strong evidence linking long-term exposure (i.e., exposure over many months or years) to air pollution with an increased risk for ischaemic heart disease, stroke, chronic obstructive pulmonary disease (COPD), lung and upper aerodigestive cancers, adverse pregnancy outcomes (i.e., low-birth rate, preterm births, stillbirths, and reduced birth weight (babies born weighing less than five pounds / 2.2 kilos)), diabetes, lower respiratory infections, and cataracts. The WHO’s International Agency for Research on Cancer (IARC) has designated outdoor air pollution as a carcinogen.

Some immediate health effects of air pollution exposure, even for a few minutes to a few hours, include irritation of the eyes, nose and throat, shortness of breath, cough, and exacerbation of pre-existing conditions, like asthma attacks and chest pain. Age, pre-existing conditions, and other risk factors for disease and sensitivity to the pollutant can all affect how a person reacts to air pollution.

Air pollutant gases can also seriously affect human health. Carbon monoxide (CO) restricts the transfer of oxygen to tissues and can be fatal in very high concentrations. Sulphur dioxide (SO2) is a potent lung irritant affecting the health of those with pre-existing respiratory disease (asthma and COPD), especially those living and working close to SO2 sources. Nitrogen oxides (NOX) are linked to a range of impacts, spanning from respiratory irritation to the development of asthma and increased mortality. Exposure to ozone (O3) causes respiratory diseases and was associated with 489,000 premature deaths in 2021, according to the 2024 State of Global Air report.

Left out of these statistics are the serious health consequences that have been associated with air pollution in scientific literature, but for which data and/or methods do not yet exist in order to estimate attributable disease burdens on a global scale, or for which more research is needed to establish causal attribution in a rigorous and statistically robust way. For example, studies have identified associations between air pollution and asthma (including childhood asthma), cognitive decline and dementia in later life, pregnancy loss, and infant mortality. As research continues to develop, and more of these health outcomes are incorporated into the Global Burden of Disease (GBD) estimates, the air pollution-related disease burden is likely to change over time.

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10. HOW DOES AIR POLLUTION AFFECT CHILDREN'S HEALTH?

Children are particularly vulnerable to the damaging health effects of air pollution due to their unique susceptibility and exposure. Children’s respiratory tracts are more permeable, their breathing rate is twice as much as adults, and they take in more air per kilogram (kg) of their body weight. Additionally, children’s bodies, especially their lungs and brains, are still developing, with narrower blood vessels. Their immune systems are also weaker than adults, making polluted air more harmful to them.

Air pollution affects a child’s growth and development, leading to lifelong impacts on their health, learning, and well-being. The harmful effects of air pollution are particularly severe in children living in socially or economically disadvantaged communities, where the rates of air pollution-related deaths among children under five remain high, especially in regions such as South Asia and East, West, Central, and Southern Africa.

According to the 2024 State of Global Air Report, in 2021, a total of 709,000 deaths in children under five were linked to exposure to air pollution, representing 15% of all global deaths in this age group. Of these deaths, nearly two-thirds (71%) were related to household air pollution (HAP), which primarily comes from burning solid fuels for cooking. The remaining deaths were attributed to ambient PM2.5, which originates from sources such as power plants, transportation, industries, and waste combustion.

To protect children from the harmful effects of air pollution, reducing reliance on burning solid fuels for cooking is crucial. Some countries have improved access to cleaner energy sources, which has reduced children’s exposure to household air pollution and likely contributed to declining rates of childhood mortality.

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11. WHAT ARE THE ECONOMIC IMPACTS OF AIR POLLUTION?

Not only does air pollution have an enormous impact on human health, crop yields, ecosystems, the climate, cultural heritage, and society, it also poses an enormous economic burden to society. The largest estimates for the economic impacts of air pollution relate to the impacts it has on human health, but it also causes economic losses due to lost productivity, reduced crop yields, and reduced competitiveness of globally connected cities. A 2025 World Bank report on air pollution found that in 2020, the economic damages associated with outdoor pollution were estimated at between US$4.5 trillion and US$6.1 trillion a year—equivalent to between 4.7 percent and 6.5 percent of global GDP. The study also found that less developing countries often suffer the greatest economic loss of air pollution. A 2021 World Bank study found that the economic cost of only the health impacts of air pollution alone totalled US$8.1 trillion, equivalent to 6.1 percent of global Gross Domestic Product (GDP) in 2019. A 2022 UNECE report found air pollution cost equivalent to more than 5 percent of GDP for countries in the ECE region (26 of 56), and more than 10 percent for at least 6 countries, without counting the loss to societal expenditures such as health-care sector expenditures.

Numerous studies have shown that controlling air pollution provides economic benefits that outstrip the cost of implementing the control measures. For example, according to the WHO, bringing air pollution down to WHO guideline levels could deliver around $246 million in saved welfare costs for the city of Accra. A 2022 study by the OECD found that coordinated air pollution action in Northeast Asia (China, Japan, South Korea) could deliver significant economic welfare benefits from improved public health and increased agricultural benefits while only negligibly impacting GDP growth.

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12. DOES GENDER IMPACT THE WAY AIR POLLUTION AFFECTS HEALTH AND WELL-BEING?

The effects of air pollution are not distributed equally among populations. Variables such as gender, race, ethnicity, migrant status, and age play a crucial role in determining both the level of exposure to air pollution at home and work, as well as the resulting health consequences and access to healthcare. To ensure fair and effective policymaking regarding air pollution, it is essential to understand and act on the uneven distribution of exposure and susceptibility to air pollution among different groups of people.

Gender plays a significant role in shaping the impact of air pollution on various populations. It influences how individuals spend their time, affecting their exposure to pollution, especially concerning work-related activities, leisure, and household responsibilities. A recent scoping review conducted by the Stockholm Environment Institute (SEI) examined existing research on air pollution's effects in the workplace in Southeast and East Asia. The findings revealed that men bear a higher health burden from total air pollution exposure, possibly due to increased exposure to air pollutants in their workplaces. Conversely, the study highlighted that women and girls experience more exposure to household air pollution, stemming from traditional division of responsibilities. Apart from direct health consequences, air pollution can also have indirect effects on women and girls, leading to increased caregiving responsibilities for family members affected by pollution.

However, gender considerations are seldom incorporated into the design and implementation of policy responses to address air pollution issues. One of the contributing factors is the lack of disaggregated data, resulting in unequal outcomes for different groups. To address this issue, obtaining high-quality and timely data that is disaggregated not only by gender but also by other factors—such as income, age, ethnicity, and location—is crucial. This data is vital in identifying those who might be left behind and ensuring their inclusion in the decision-making process. By meaningfully integrating gender dimensions into the assessment of air pollution impacts and the development of mitigation measures, society as a whole can benefit, leaving no one behind in the fight for clean air.

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13. IS THERE A SAFE LEVEL OF AIR POLLUTION TO PROTECT YOUR HEALTH?

While all individuals experience different levels of health impacts from air pollution, across large city or country populations, there is no evidence of a completely safe level of air pollution, especially in the case of particulate matter and NO2. However, to help guide countries achieve cleaner air for health, the WHO has set normative guideline values for all major air pollutants. Compliance with those values would protect public health from adverse effects. In 2021, the WHO published updated air quality guidelines for common air pollutants as well as interim target levels for PM (PM2.5 and PM10), O3, NO2, and SO2.

This does not mean that there are no health effects below those guidelines; however, available studies do not include sufficiently large populations with exposure levels below those concentrations. The guideline values represent health-based targets useful for tracking the burden of disease from air pollution, informing national-level targets and standards, and monitoring the effectiveness of air quality management efforts designed to improve health.

Many countries have established national air quality standards, which can be found in the WHO Air Quality Standards database. National standards may differ from country to country and may be above or below the respective WHO guideline value. It is a policy issue to decide which specific at-risk groups should be protected by the standards, and what degree of risk is considered to be acceptable. However, the number of countries with no or insufficient regulations is still very high, especially in the developing world, and the new WHO values are indeed substantially lower. This means almost all countries will need to set strategies for further clean air policies towards meeting the WHO interim goals and ultimately its guideline values.

The UNECE Convention on Long-range Transboundary Air Pollution has also provided threshold (critical) levels for ozone (O3), above which impacts on crops, forests, and grasslands can occur.

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14. WHAT EFFECT DOES AIR POLLUTION HAVE ON FOOD, CROPS, FORESTS AND BIODIVERSITY?

Ozone (O3) is by far the main air pollutant affecting plant growth. It reduces crop yields, forest health and biodiversity generally. Different plant species have different sensitivity to O3; those more sensitive to O3 will have reduced competitive advantage in ecosystems, while more resistant species will become more dominant. Some crops are very sensitive to O3, especially beans and wheat. Soybean yields, for example, can be reduced by 15% or more. Yield losses due to O3 might put pressure on crop markets and prices, thereby affecting crop availability and accessibility and hence regional food security. There is also a knock-on effect on the climate, as the reduced growth of forest trees caused by O3 pollution, reduces the ability of forests to absorb carbon dioxide and their potential to help regulate climate change.

Other pollutants like sulphur and nitrogen can also damage forest and lake ecosystems through acidification of soils and surface water, affecting forest growth and killing fish and other organisms. Nitrogen deposition also causes eutrophication (over-fertilisation) of low nutrient ecosystems such as heathlands, causing large shifts in biodiversity.

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15. HAS AIR POLLUTION BEEN SOLVED ANYWHERE?

Air pollution has not been solved in any region, but there have been remarkable decreases in emissions and pollutant concentrations in many European countries, as well as the USA, Canada, and Japan, China where strong policies, regulations, and regular monitoring systems as well as long-term international cooperation have been put into place.

One of the most famous examples is London, which had some of the worst levels of pollution, with peak total particulate concentrations at the end of the 19th century. Since then, air quality in the UK has improved remarkably. Particulate air pollution levels fell by over 97% between 1900 and 2016. Other cities and regions have also shown significant reductions. However, this does not mean that air pollution has been solved. In London, PM2.5 remains higher than the WHO air quality standard.

Beijing, once notorious for its air pollution problem, has in the last 20 years taken increasingly aggressive steps to reduce air pollution and its air quality has improved substantially. Similarly, in 1992, Mexico City was labelled as the world’s most polluted city, but in 1995, the government launched an extensive programme named ProAire with concrete measures to increase public awareness and achieve sustainable development in eight areas including reduction of energy consumption, cleaner and more efficient energy and promotion of public transport. Mexico City’s air pollution has decreased by nearly 60% since the introduction of ProAire. From a peak in 1989, O₃ levels decreased by two-thirds by 2015—still high enough to cause significant health impacts, but a massive reduction, nevertheless.

Aerosols and photochemical oxidants (like ozone) can also create haze and reduce visibility, which can shroud cities in dense smog. During the London Smog Disaster (see question 7) and similar pollution episodes, visibility was extremely low. The strong link between visibility and pollution was illustrated when people in parts of Northern India could see the Himalayas for the first time in a generation, when air pollution levels fell due to the lock-down and reduced emissions, caused by the COVID-19 crisis. Falling concentrations in North America and Europe has reduced this haze significantly, but it is very prevalent in other parts of the world, especially in Asia. Multiple similar events indicate that reduced visibility is a clear and intuitive indicator of poor air quality, often associated with high health risks, while improved visibility reflects a temporary decrease in air pollutant emissions caused by human activities.

These decreases show that air pollution is a problem that we know how to solve, and that there are policies and technologies needed, and indeed in principle available, to achieve cleaner air. In many countries, improved air quality has happened while countries have increased in wealth. This means that unlike in the past, where air pollution was considered an unavoidable cost of economic growth, air pollution reduction does not impact economic growth. It is effectively decoupled from wealth creation.

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16. WHAT IS THE ROLE OF AIR QUALITY MONITORING IN AIR QUALITY MANAGEMENT?

There are several challenges countries face when addressing air pollution. Monitoring air quality can be a complex and costly undertaking, and there are large disparities in capacity worldwide. The cost of certified monitoring equipment, as well as regular calibration and maintenance, can be a heavy burden to many local authorities and national governments. Globally, 39% of countries have no public air quality monitoring in place and 37% of countries have no legal requirement to monitor air quality. In countries with limited resources, monitoring sites are often only located in their largest, most populated city. The air quality data gap is especially notable in Africa.

Many countries have no government-run monitoring networks using regulatory-standard equipment at all. In countries with limited resources, monitoring sites are often only located in their largest, most populated city. Many cities in developing countries can only afford to have a single monitoring site, or a few at most. This is something that needs to be addressed.

In many places, private companies are developing lower-cost air quality sensors that people can install in their own homes. This is leading to networks of citizen scientists reporting on air quality and citizen led online air quality databases. Though these datasets are growing, the data must be used with caution for the individual and public decision making. A cross-calibration of these low-cost sensors with high quality, regulatory monitoring devices is strongly recommended, as is a double or triple installation of low-cost sensors at each location for purposes of comparison (faulty devices can then be easily detected). Recently, successful approaches of combining a small number of high-precision regulatory monitoring devices with a large number of low-cost sensors to record the air pollution concentration across the area of entire cities have been developed.

It is important to note that the cost of air quality monitoring is much lower than the cost of air pollution reduction, the former typically being a public investment and the latter typically a private investment. However, in some countries, charities, healthcare providers and universities have been active in helping to deploy monitoring networks to provide higher quality public information on air pollution.  It therefore makes sense for national governments and cities in developing countries to consider partnering with key stakeholders to prioritize and invest in the establishment, operation, and maintenance of ground-level regulatory-standard air quality monitoring networks, to generate reliable data on air quality.

For more information see here:

17. HOW DO I KNOW THE LEVEL OF THE POLLUTION PROBLEM IN MY COMMUNITY?

Many cities that have implemented monitoring networks to continuously measure air pollutants as part of their air quality management systems regularly report an Air Quality Index (AQI) designed for public information purposes. An AQI is easy to interpret, and often color-coded, to warn of dangerous levels of air pollution. It varies between countries, as each country develops its own index based on its own air quality standards. This information is accessible through websites, newspapers, and apps.

The availability of air quality monitoring is unequal globally and regionally. This is because high quality monitors are expensive, as is the cost of training people to run and maintain monitoring networks. Even in places with good monitoring, there are disparities. For example, in some parts of Europe, there are very dense monitoring networks, while in other parts the networks are less dense. In many developing countries across the world there is no official air pollution monitoring.

Investing in air quality monitoring is very important because the larger the networks are, the more information we can have for a city, a region, or a country. As the robustness and reliability of the network improve, it can complement other tools such as emission inventories, model simulations, and remote sensing data. This information can be invaluable for helping people understand the air pollution levels where they live and take action to reduce their exposure. It’s also important for governments, to be able to make short and long-term planning decisions to reduce air pollution. According to UNEP’s first global assessment of air quality legislation, 37% of countries do not currently require monitoring mechanisms in their national air quality management systems.

In many places, private companies are developing lower-cost air quality monitors that people can install in their own homes. This is leading to networks of citizen scientists reporting on air quality and citizen led online air quality databases. Though these datasets are growing, the data must be used with caution for individual and public decision making. A number of international and civil society organizations and private companies also collect and report air quality information, often based on a combination of monitoring and satellite data. Where local information is unavailable, these can be useful resources to understand the air pollution problem in your city or country. For example, the WHO Air Quality Database compiles data on ground measurements of air pollutants from over 8,600 human settlements in more than 120 countries. The database is updated every 2–3 years and was last updated in January 2024.

For more information see here:

18. WHAT ACTIONS CAN GOVERNMENTS TAKE TO IMPROVE AIR QUALITY?

Governments are responsible for providing their citizens with clean air. There are multiple options for national and local governments to improve air quality. Air pollution is a problem that we know how to solve.

Air pollution impacts everyone, and its sources and solutions are diverse. Actions to reduce air pollution require cooperation among various sectors and stakeholders (including the public), different levels of government, and among governments and regions. However, clean air strategies vary in approach according to the context of each country and city, as well as its capacity to develop and implement control measures. There is not one uniform policy prescription for air quality that is applicable to all cities, countries and regions; such an approach would be neither possible nor desirable for a problem that is so diverse in local circumstances.

Governments should invest in capacity to measure and monitor air pollution by establishing monitoring networks and ensuring that such networks are properly operated, maintained, and subjected to procedures that guarantee the quality and reliability of air quality measurements.

The first step towards responsible management of air pollution is to make sure that necessary laws, regulations, policies, and enforcement mechanisms are in place and sufficiently supported. It is equally important that the government to act on known sources, even in the absence of detailed data on levels of air pollution or emissions from different sectors. Governments should ensure that the appropriate institutions have sufficient capacity to monitor and assess air pollution emissions and utilizing the data for decision making. This will ensure that decision makers know where their air pollution comes from, how large the different sources of emissions are, the levels of air pollution in different parts of their country, the impacts on health, and what high impact actions can be taken to reduce pollution levels and reduce the harm caused.

Where capacity to undertake such activities is limited or local data is not available, there are still resources available to help countries understand the scale of their air pollution problem and identify priority actions. These include sources for emissions, estimated by global programmes (e.g. EDGAR emission estimates), or concentrations and health impacts (WHO, IHME, State of Global Air), estimated from satellites and global modelling, with ground truthing from monitoring stations. These datasets have their limitations and uncertainties and should be used in the cases where local data are not available, or where there is limited monitoring capacity.

It is important that governments understand the benefits and costs associated with alternative actions or interventions to improve air quality; and to prioritize actions. Most air pollution reduction measures have health and social benefits that far outweigh the costs of implementation.

Strengthening institutions and governance, promoting behavioural change, instilling a pro-clean air culture, increasing the capacity in all sectors to effectively engage and contribute to solutions, political will, and increased funding, are also key elements of success.

Governments should invest in capacity to measure and monitor air pollution by establishing monitoring networks and ensuring that such networks are properly operated, maintained, and subjected to procedures that guarantee the quality and reliability of air quality measurements.

Finally, it is of utmost importance and duty that governments inform the public about the policies, measures and technologies being used to monitor and reduce air pollution – and to provide easy-to-understand analyses of the impacts these actions have on air quality. Equally important is that the governments promptly publicise the monitoring data, for example by publishing AQI values based on these data.  A simple and effective way to interact with the public and create a sense of ownership of solutions to the problem of air pollution is citizen science approaches, which have been successfully trialed in developed and developing countries.  

For more information see here:

19. WHAT CAN I DO TO IMPROVE AIR QUALITY IN MY COMMUNITY?

The most important thing people can do is to get informed about the levels of air pollution where they live and how it affects them, and to demand that the government and the private sector take steps to reduce air pollution in their city, region, or country. Most sources of air pollution are structural and embedded in the economic processes underpinning modern society. Individuals will not be able to eliminate large sources of air pollution entirely on their own, or they may be in a limited position to change their behaviour to reduce air pollution exposure—some actions can be done to reduce personal contribution to air pollution (see below). This is an equity issue that will need a collective effort and the burden of reducing air pollution should not be put on individuals. The most effective solutions lie in reducing emissions, something that requires strong political will as well as laws and bold action from governments and cities, at the policy level. The burden of reducing air pollution should not be put on individuals, but that doesn’t mean individual voices don’t matter.

Individuals can take some actions to reduce air pollution and their exposure to air pollution, including (see below). Including avoiding high-pollution areas (such as congested roads), adjusting outdoor activities to times when air quality is better, keeping windows closed during periods of poor air quality, using air purifiers indoors, and wearing well-fitting particulate masks when necessary. In addition, some of the actions individuals can take to reduce their personal contribution to air pollution include:

  • choose clean modes of transport when available (e.g. public transport, cycling or walking rather than private cars or motorbikes);
  • if you’re considering buying a car, look at the fuel economy, emissions standard and check the real world emissions for that car. Buying a hybrid or electric vehicle or smaller engine capacity vehicles will also help to cut down your contribution to emissions;
  • where available, use available and clean (low and ultra-low Sulphur) fuels together with advanced vehicle emissions control technologies identified above;
  • if you have a car, ensure it is serviced regularly to minimise its contribution to air pollution;
  • use clean fuels and technologies for cooking, lighting and heating wherever possible;
  • use renewable energy sources wherever possible;
  • stop burning household and agricultural waste;
  • eliminate fireplace and wood stove use;
  • reduce your carbon footprint in general (leisure travel, food options choices, sustainable consumption of goods, etc);
  • monitor your energy demand and waste at home and install energy-efficient appliances and light bulbs, insulation and draught-proof windows;
  • support policies, economic incentives and regulations which increase access to the actions/choices above; and
  • join a local group of citizen scientists to help monitor local air quality and support data collection and reporting to build an evidence-base for action (see Question 19).

 

For more information see here:

20. WHAT ACTIONS CAN BUSINESSES TAKE TO REDUCE AIR POLLUTION?

Businesses and industry have a key role to play in reducing air pollution, since many of their activities produce different types of air pollutants. The private sector can contribute to air pollution reduction through its various operations and supply chains across different sectors. Pollution sources from the private sector range from burning fuels, to distribution and delivery vehicles. Since air pollution also contributes to climate change, companies that pledge to reduce their air pollution emissions can simultaneously reduce their carbon footprint. This double win reducing air pollution and their carbon footprint can and has been the driver of innovative solutions from the sector. In the past, these solutions have mostly been technological (e.g. switching from one technology to another), but some parts of the private sector may need to move beyond those technological solutions. There are several actions the private sector can take to reduce air pollution:

  • Add air quality to their Corporate Social Responsibility activities and pledge to regular reporting and monitoring.
  • Identify, quantify, and report air pollution emissions along with co-emitted greenhouse gases from separate facilities, manufacturing processes and supply chains.
  • Establish programmes that reduce air pollution, specific to each sector including implementation of best available techniques and best environmental practices and adopting measures to improve energy efficiency.
  • Promote awareness campaigns to transparently communicate the levels of emissions caused by their operations and explain what they will do to reduce those emissions.

One example of how a large industry can act to reduce air pollution is presented in a report by the International Aluminium Institute (IAI), ‘Sustainable Bauxite Mining Guidelines’, which includes air quality.

World Economic Forum’s Alliance for Clean Air : the first global corporate initiative to bring together leading businesses to tackle air pollution.

Launched at COP26 by the World Economic Forum, in partnership with the Clean Air Fund, the Alliance’s founding members include Accenture, Bloomberg, Biogen, Google, GoTo, IKEA, Maersk, Mahindra Group, Siemens and Wipro. The Alliance has now grown and includes, Oracle, EY, Moderna, Haleon, GSK, and GEA.

Alliance members commit to:

  • Establish air pollution footprints on nitrogen oxides, sulphur oxides, and particulate matter within 12 months
  • Pinpoint where they are being emitted to track human exposure
  • Set ambitious targets and objectives to reduce the air pollution emissions, with a clear action plan
  • Act as champions for clean air by raising awareness among employees, customers and communities about the impact of air pollution. They will also help them to reduce their exposure and support them to take action to reduce pollution
  • Use their assets innovatively to accelerate clean air solutions
  • Measuring and reducing: establish air pollutant emissions inventory using a science based guide and set ambitious reduction targets
  • Developing sector specific solutions: focused on transport and energy consumption based on mitigations developed by members
  • Integrating air quality into networks and with policy makers: collaborate with national and local governments and engage industrial groups
  • Supporting innovation and finance: promote or develop technology to reduce air pollution and mobilise resources
  • Championing: Act as champions by raising awareness among stakeholders about the impact of air pollution and inspire companies to bring air quality into their climate movements.

Alliance members are implementing using the  Practical Guide for Businesses on how to quantify air pollutant emissions across value chains. This Guide was developed is, being developed by the Stockholm Environment Institute, Climate and Clean Air Coalition, in co-operation with IKEA and an updated version has recently been published which incorporate more emissions factors and is based on feedback from companies.

 11 of the Alliance members have already published their air pollutant emissions as part of their sustainability reports including IKEA, Maersk, GoTo, Bloomberg, and Biogen, Wipro, Hydro, GEA, Haleon, Oracle and Accenture.

For more information:

21. WHAT ARE THE FINANCING OPTIONS TO IMPROVE AIR QUALITY?

Improving air quality doesn’t have to break the bank. New research from the World Bank shows that the investment needed to accelerate access to clean air is affordable, and governments don’t have to rely entirely on limited public funds. By creating clean air markets, policymakers can attract private investment to help scale up solutions.

Many clean air measures, such as switching from fossil fuels to renewable energy or improving energy efficiency, are already commercially viable. These solutions are widely available, come with low financial risk, and often pay for themselves quickly. To unlock even more investment, especially in areas like green mobility, clean cooking and heating, and low-emission fertilizers, governments can take the following actions:

  • Align incentives to encourage private sector participation
  • Remove fossil fuel and fertilizer subsidies and repurpose them for clean alternatives
  • Use public procurement to drive demand for clean technologies
  • Enact clear regulations that support clean air goals

Development finance institutions also play a key role by offering innovative financial tools and helping to reduce investment risks for private funders.

The World Economic Forum recommends five actions to boost air quality investments:

  • Raise awareness about the health and economic impacts of air pollution across funding institutions
  • Integrate clean air goals into projects across sectors like energy, transport, and urban planning
  • Prioritize projects that improve air quality and clearly benefit public health and the economy
  • Encourage collaboration among funders to share commercial and development risks among air quality projects
  • Use de-risking tools to attract private capital

The right financing approach depends on the project. It could include financial support to agreed air quality policy reform, grants for technical assistance, or partnerships between governments, business, and donors. For more information on clean air funding opportunities and partnerships, visit UNEP’s clean air finance resources.

 

For more information see here:

22. HOW ARE AIR POLLUTION AND CLIMATE CHANGE CONNECTED?

Air pollution and climate change are inherently linked. Major air pollutants have an impact on the climate, and most share common sources with greenhouse gases (GHGs), especially related to the combustion of fossil fuels. They also aggravate each other in multiple ways. For example, the dangerous GHG methane contributes to the formation of ground-level ozone, and levels of ground-level ozone increase with rising temperatures. One increasingly important link between air pollution and climate change is wildfires. The rising temperature increases the frequency, severity, and duration of wildfires, which in turn further elevate levels of particulate air pollution. With climate change leading to warmer and drier conditions, the fire season is starting earlier and ending later. Wildfires are increasingly more extreme, burning larger areas and with greater duration and intensity. Wildfire smoke is a mixture of hazardous air pollutants and can also impact the climate by releasing large quantities of CO2 and other greenhouse gases into the atmosphere. According to Europe’s Copernicus Atmosphere Monitoring Service (CAMs), Canadian wildfires emitted 290 Mt of carbon into the atmosphere between 1 January and 31 July 2023, nearly double the previous record for the year as a whole.

Substances classified as air pollutants can warm the atmosphere, and others can cool it, emphasising the link between air pollution and climate change. Black carbon and tropospheric ozone both contribute to warming and are harmful air pollutants. Short-lived climate pollutants (SLCPs) include black carbon and tropospheric ozone as well as methane—which leads to tropospheric ozone formation—and hydrofluorocarbons (HFCs). Implementing measures to reduce black carbon and methane emissions reduces the rate of near-term global warming, and they also significantly reduce ozone formation, which benefits human health.

Reducing methane is one of the most cost-effective strategies to rapidly reduce the rate of warming while simultaneously protecting human health and crop yields because reducing methane will lead to less tropospheric ozone formation. Integrated actions, such as those that target SLCPs, can therefore provide triple-win scenarios by achieving real-world multiple benefits for human health, agriculture, and the climate.

What should our response be to reductions in cooling aerosols?

The relationship between air pollution and climate change is complex. Reducing air pollution can have both cooling and warming effects on the climate. Some air pollutants—like sulphate aerosols that are primarily emitted from fossil fuel combustion—temporarily cool the planet by reflecting sunlight back into space. These cooling aerosols have increased dramatically since the industrial revolution, but they have started to decrease in recent decades in the United States thanks to public health policies.

Cooling aerosols are short-lived in the atmosphere, but their large quantities currently mask up to 0.5 °C of the warming that greenhouse gas emissions would otherwise be observed, according to the IPCC. As sulphates are reduced to improve air quality and public health, this “cooling mask” diminishes, leading to increased near-term warming, an effect that scientists have understood for decades. This “unmasking” has been observed in regions such as North America and Europe, where aerosol emissions and their cooling effects peaked in the late 20th century. Globally, reductions in aerosols also have measurable effects: a recent study linked a 75 per cent drop in sulphate emissions in East Asia to 0.07 °C of warming, a significant amount given that every tenth of a degree matters. 

Importantly, some of the same human activities that release cooling aerosols like sulphate are also major sources of CO2, meaning that reductions in these aerosols will inevitably occur as economies decarbonize. Over the longer term, the CO2 emission decreases will lead to a reduction in warming caused by this major greenhouse gas, but the sharp decreases in cooling aerosols may cause limited temporary warming in the very near term (a matter of years). The response to this is not to keep releasing sulphate, as this will continue to harm human health and ecosystems, but to concentrate on reducing the SLCPs. Reducing emissions from key sources of Short-Lived Climate Pollutants (SLCPs)—especially the main sources of methane—that, like aerosols, have short atmospheric lifetimes and strong near-term climate impacts, can offset a proportion of the near-term increases in temperature from reducing sulphates

Falling to act on air pollution is not an option for climate mitigation. Reducing particulate pollution and improving air quality remains a top priority for the benefits it brings to human and ecosystem health. The interlinkages between air pollution and climate change provide an opportunity to amplify the benefits of our actions and catalyse even greater mitigation ambition, and knowledge about how air pollution and climate change are connected can be implemented into policies that can avoid some of these trade-offs. Win-win strategies to rapidly reduce warming must therefore integrate actions to reduce all air pollutants and greenhouse gases that contribute to both near- and long-term climate impacts, for example, phasing out fossil fuels and promoting electric vehicles. This will put the world on a trajectory that maximizes benefits, reduces the risk of policy failure, and delivers national development priorities.

 

Methane is a clear multi-win option for air quality and the climate

The IPCC Sixth Assessment report identified methane as a clear option for achieving substantial near- and long-term avoided warming while simultaneously achieving air quality benefits by reducing ground-level ozone concentrations. Methane is a an extremely powerful greenhouse gas, responsible for about 30 per cent of warming since pre-industrial times. Unlike CO2 which stays in the atmosphere for 100s of years, methane starts breaking down quickly, with most of it gone after a decade. This means cutting methane emissions now can rapidly reduce the rate of warming in the near-term. Because methane is a key ingredient in the formation of ground-level ozone (smog), a powerful climate forcer and dangerous air pollutant, a 45 per cent reduction would prevent 260 000 premature deaths, 775 000 asthma-related hospital visits, 73 billion hours of lost labour from extreme heat, and 25 million tonnes of crop losses annually.

Recognizing the importance of rapid methane abatement, since 2021, over 100 countries, representing more than 50% of global anthropogenic methane emissions and over two thirds of global GDP have joined the Global Methane Pledge. Participating countries have agreed to act to reduce global methane emissions at least 30 per cent below 2020 levels by 2030.

For more information:

  1. Global Methane Assessment: Summary for Decision Makers

 

For more information:

23. WHAT PROGRESS HAS BEEN MADE FOR AIR QUALITY-RELATED SDG INDICATORS OVER THE PAST FIVE YEARS, AND WHAT ARE THE OPPORTUNITIES FOR THE NEXT FIVE YEARS?

While progress towards achieving nearly all the Sustainable Development Goals (SDGs) would indirectly improve air quality, there are three SDG progress indicators that are directly linked to cleaner air. Indicator 3.9.1 measures the number of deaths linked to air pollution exposure. Indicator 7.1.2 measures the proportion of the global population using primarily clean fuels and technologies. Indicator 11.6.2 measures annual average levels of particulate matter air pollution in cities.

Since monitoring and reporting on progress towards the SDGs began in 2015, the world has seen slow but steady progress towards cleaner air. As a global average concentration of fine particulate matter decreased by 9 per cent between 2015 and 2019 and now stands at the WHO Air Quality Guideline (AQG) Interim Target 1 value of 35 µg/m3 (SDG11.6.2). However, this progress towards cleaner air has not been equal in all regions, with some regions, particularly those with rapidly growing populations, experiencing increasing air pollution over this period. For example, Sub-Saharan Africa saw a deterioration in PM2.5 concentrations between 2015 - 2019, while the region's population grew at an annual rate of approximately 2.6 to 2.7% during those years. Northern Africa and West Asia also experienced persistent high PM2.5 exposure, with an annual 1.5% population growth rate.

In 2023, there remained a significant global disparity in access to clean fuels and technologies for cooking, with 89% of urban households having access compared to only 55% of rural households (SDG7.1.2). Worryingly,  Sub-Saharan Africa (SSA) is the only region that has a continuously rising number of people without access to clean cooking, reaching around 1 billion today and affecting roughly four in every five households.

Furthermore, the burden of air pollution linked to deaths is overwhelmingly borne by the most vulnerable. In 2019, low-middle-income countries (LMIC) endure 93% of the burden from mortalities attributed to household and ambient air pollution (SDG3.9.1).

International cooperation and multisectoral actions are needed to accelerate progress in the next 5 years. Pivotal to the improved air quality in Eastern Asia and Southeastern Asia regions is the increase in countries' monitoring capacity. Since 2011, there has been a six-fold increase in air quality monitoring in cities across the globe. Despite the increasing trends, the unequal monitoring capabilities in high-income countries vs LMIC needed to be urgently addressed. Clean cooking solutions also need to be scaled up. With stepped-up interventions, around 1.8 billion people or 21% of the world’s population could have access to clean cooking by 2030. Gender equality needs to be recognized as well during the interventions as health risks from household air pollution are particularly high among women and children. If we are to truly leave no one behind, we must ensure that all countries, regardless of their income status, have access to clean air and energy.

For more information see here:

24. IS CLEAN AIR A HUMAN RIGHT?

Yes. The human right to clean air was first recognized by the United Nations General Assembly in 2022 with the adoption of Resolution 76/300 on the human right to a clean, healthy, and sustainable environment. The Resolution follows a similar landmark recognition by the UN Human Rights Council in October 2021, which recognized for the first time that having a clean, healthy, and sustainable environment is a human right. These resolutions build on a 2019 report by the Special Rapporteur for Human Rights and the Environment.

The UN General Assembly resolution is not legally binding but can be powerful catalyst for action and expansion of legal rights in other jurisdictions. For example, at least 155 countries are legally obligated, through treaties, constitutions or legislation to respect, protect and fulfil the right to a healthy environment. Obligations related to clean air are also implicit in several international human rights instruments, including the Universal Declaration of Human Rights and the International Covenant on Economic, Social, and Cultural Rights.

For more information see here:

Current List of Clean Air Day Science Group: 
Johan C. I. Kuylenstierna (Chair of the Science Group, SEI).
Ilse Aben (SRON), Heather Adair-Rohani (WHO), Ava Bahrami (UNEP-CCAC), Sara Basart (WMO), Kalpana Balakrishnan (Sri Ramachandra Institute of Higher Education and Research), Luis Carlos Belalcazar Ceron (UNAL), Nathan Borgford-Parnell (UNEP-CCAC), Patric Bueker (GIZ), Michael Brauer (UBC), Atif Ikram Butt (UNEP), Kristin Campbell (UNEP-CCAC), Julia Codina Sariols (UNEP), Gabrielle Dreyfus (IGSD), Lisa Emberson (University of York), Johannes Flemming (ECMWF), Rebecca Garland (University of Pretoria), Sophie Gumy (WHO), Tatsuya Hanaoka (NIES), Andrea Hinwood (UNEP), Jiang Kejun (HKUST), Kenza Khomsi (UNIDO), Gary Kleiman (ORBIS AIR), Lorenzo Labrador (WMO), Marcelo Mena (GMH), Eleni Michalopoulou (SEI), Pierpaolo Mudu (WHO), Maria Katherina Patdu (UNEP), Pallavi Pant (HEI), Mihaela Paun (UNEP), Matthew Perkins (UNESCAP), Shonali Pachauri (IIASA), Scarlett Quinn-Savory (UNEP-CCAC), A. R. Ravishankara (COLOSTATE), Kerolyn Katrina Shairsingh (WHO), Drew Shindell (Duke University), Sophie Szopa (ISCE), Soraya Smaoun (UNEP), Oksana Tarasova (WMO), Evelyne Toure N'datchoh (Université Félix Houphouët-Boigny), Chandra Venkataraman (IITB), Young Sunwoo (KONKUK), Jingyi Ye (UNEP-CCAC), Eric Zusman (IGES), and Maria Cristina Zucca (UNEP).

 

Contributor to this year’s FAQ: 
Heather Adair-Rohani (WHO), Thomas Bannister (UNEP), Sara Basart (WMO), Amanda Michelle Curry Brown (UNEP-CCAC), Nathan Borgford-parnell (UNEP-CCAC), Kristin Campbell (UNEP-CCAC), Gabrielle Dreyfus (IGSD), Sophie Gumy (WHO), Andrea Hinwood (UNEP), Johan C. I. Kuylenstierna (SEI), Lorenzo Labrador (WMO), Paolo Laj (WMO), Juliette Laurent (UNEP-CCAC), Eleni Michalopoulou (SEI), Pallavi Pant (HEI), Samantha Pegoraro (WHO), Matthew Perkins (UNESCAP), Julia Sariols (UNEP), ,  Katrina Kerolyn Shairsingh (WHO), Sophie SZOPA (ISCE), Jingyi YE (UNEP-CCAC), Maria Cristina Zucca (UNEP).

UN Environment