WHO’s updated indicators reveal stark disparities between low- and high-income countries.

WHO has launched updated data on the Sustainable Development Goal (SDG) indicators tracking the link between air pollution and health. The release of data on ambient and household air pollution highlights critical inequalities: while fine particulate matter (PM2.5) levels dropped globally until 2020, they have since remained largely unchanged, with low- and middle-income countries facing significantly higher exposure risks than high-income nations, increasing risks for public health and the environment.

“As the custodian of environmental health-related SDG indicators, WHO is committed to providing robust, evidence-based data, which is essential for bold decision-making,” says Bruce Gordon, Director a.i., Environment, Climate Change, One Health and Migration, WHO.

“We cannot address the climate and air pollution crisis or protect public health without reliable information that highlights global inequalities and disparities,” Bruce says, adding, “Placing science at the forefront to drive monitoring and foster multi-sectoral collaboration is crucial to ensuring universal access to clean air and energy, safeguarding both the health of people and planet – now and for future generations.”

Key findings on global inequalities

In 2023, the number of people exposed to air quality exceeding the least stringent interim target of 35 ug/m3, proposed by WHO’s global air quality guidelines was thirteen times higher in low- and middle-income countries than in high-income ones, affecting 6.5 billion people.

In 2024, approximately 2 billion people still relied on inefficient stoves and fuels for cooking, leading to high levels of health-damaging pollutants in and around the home. Exposure to both ambient and household air pollution drives a heavy burden of noncommunicable diseases, including heart disease, stroke, chronic obstructive pulmonary disease and lung cancer, and especially impacts the most vulnerable communities and at-risk populations.

As a consequence of being exposed to unsafe levels of air pollution, low- and-middle income countries bear 90 per cent of these impacts, from which 83 per cent are due to noncommunicable diseases, such as ischaemic heart disease, stroke, chronic respiratory diseases and lung cancer, WHO says.

Regional trends show uneven progress

At the regional scale, levels and trends in fine particulate matter are uneven. Asia bears the highest levels of air pollution, but also displays the greatest progress, while some regions have remained essentially unchanged over the last decade, such as Africa, western Asia and northern Africa. In cities, air pollution is usually higher than in rural areas. However, cities have shown great reductions irrespective of their income level. In contrast, progress in rural areas differs depending on income levels, with some rural area levels increasing in low-income countries.

A similar pattern of inequality can also be seen for populations with access to clean cooking. While access has almost doubled in most of Asia since 2010, the population without access is growing in Oceania (excluding Australia and New Zealand), sub-Saharan Africa, western Asia and northern Africa. In urban areas, the access rate is 89 per cent. But of the 2.0 billion people without access to clean household energy, 1.5 billion people live in rural areas. Around 970 million people lack access in sub-Saharan Africa alone, and that figure may reach 1 billion by 2027. By 2030, 58 per cent of the global access deficit is projected to fall within sub-Saharan Africa.

The new data focus on three key environmental health indicators tracked by WHO:

• SDG 3.9.1: Mortality rate attributed to ambient and household air pollution
• SDG 7.1.2: Proportion of the population relying on clean fuels and technologies
• SDG 11.6.2: Annual levels of fine particulate matter (PM2.5) in cities.

A unique source of official data

The SDG data provide internationally comparable datasets informed by country data through an iterative country consultation process, a formal exchange where WHO requests input on air quality and household energy from national governments. While much of this input is already publicly available, this process creates a unique, harmonized source of official data.

The methodology combines diverse data streams to ensure accuracy:

• SDG 7.1.2 relies on data from household surveys and census data regarding fuel types, compiled in WHO’s household energy database, and country, regional and global estimates derived in a statistical model developed in collaboration with the University of Glasgow;
• SDG 11.6.2 uses a satellite product that combines multiple observations and atmospheric models, that is recalibrated with national air quality monitoring data from the WHO Air Quality in Cities database and population data from the Global Human Settlement Layer through collaborations with the University of Manchester and World Meteorological Organization; and
• SDG 3.9.1 links the previous two indicators (as exposure proxies) to WHO Global Health Estimates and high-quality epidemiological evidence quantifying the health impacts.

Importance of multi-sectoral collaboration

With WHO leading the monitoring of these indicators, it provides an opportunity for cross-sectoral collaboration to ensure the health perspective is included in decision-making across the health, energy, transport, agriculture and other sectors. The data are the foundation of WHO’s work to tackle pollution at its source, which is the most effective way to protect public health.

Fostering health impact assessment of air pollution

To support countries, WHO also provides tools to quantify the health, climate and economic benefits of sectoral policies, such as

• the software tool AirQ+ calculates health impacts from air pollution and air pollutants are also analyzed in the Climate Change Mitigation, Air Quality and Health (CLIMAQ-H).;
• the Benefit of Action on Household Air Pollution (BAR-HAP) tool models policy scenarios to accelerate clean energy access; and
• the SCORE tool has been developed to strengthen data collection, often a major missing data gap in health impact assessment.

From evidence to policy action

Reliable data is the foundation for robust air quality legislation, functional monitoring systems and accountability mechanisms. These updated indicators are fundamental evidence to tracking countries’ progress and leveraging the health sector for advocacy as well as ensuring that data translate into concrete policy actions that protect public health and mitigate climate change.

All these efforts aim to support WHO’s target of a 50 per cent reduction in air pollution-related mortality by 2040, while contributing to the SDG target of universal access to clean cooking by 2030 and the global roadmap ambition to eliminate cooking poverty.