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11 March 2026

Knowledge Global

Breathe Better: How Leading Cities Have Rapidly Cut Air Pollution

Air pollution remains the largest environmental health risk worldwide, with cities often experiencing some of the worst impacts. But they are also uniquely positioned to drive rapid improvements in air quality. Breathe Cities’ new research analyses air quality trends in 19 cities across 9 countries that reduced toxic air pollution by at least 20%, demonstrating that improvements in air quality are not only possible, but achievable at scale.

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Air pollution remains the largest environmental health risk worldwide. It causes cardiovascular and respiratory disease, increases childhood asthma, contributes to premature birth and low birth weight, and disproportionately affects lower-income communities.

Cities are at the frontline of this air pollution challenge. The concentration of vehicles, buildings and industry in cities creates large sources of emissions, which their dense populations are exposed to on a daily basis. The health, economic and social costs are therefore often felt most acutely in urban areas.

However, cities are also uniquely positioned to act. They play a central role in transport planning, land use, enforcement and public investment. City leadership can drive rapid and sustained improvements when aligned with national policy and regional frameworks.

The Breathe better: How leading cities have rapidly cut air pollution report examines air quality trends in C40 and Breathe Cities between 2010 and 2024. It identifies 19 cities that achieved remarkable reductions of at least 20% in both fine particulate matter (PM2.5) and nitrogen dioxide (NO2) over the past 15 years, in some cases achieving reductions of around 45%.

Highlights

New research shows how nineteen cities across Europe, North America and Asia have cut both PM₂.₅ and NO₂ by at least 20% since 2010, with some achieving reductions of nearly 45%.

Major improvements in urban air quality are achievable within just 10–15 years when cities take sustained action to reduce the biggest pollution sources.

Nearly half of the cities achieving the largest reductions are in Central and East Asia, demonstrating that rapid clean air progress is possible even in fast-growing urban regions.

These cities span Europe, North America and Asia. Notably, nearly half of the leading cities are in Central and East Asia, proving that rapid structural improvement is not confined to long-established regulatory systems. It is also highly achievable in fast-growing, densely populated contexts as well.

To understand what successful action looks like in practice, this report analyses the common systems, governance structures and policy reforms implemented across these 19 cities. The aim is not to attribute progress to a single intervention, but to identify common elements that underpin rapid and sustained improvement that can inform future action.

The report also provides a deeper look at two of the leading Breathe Cities, Paris and Warsaw, showing how they have applied the Breathe Cities approach across data, policymaking, and community engagement to successfully tackle air pollution. Finally, the report turns to two Asian Cities, Jakarta and Bangkok, highlighting how these more recent Breathe Cities are applying and expanding the Breathe approach in order to achieve similar improvements in air quality.

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