19 cities cut air pollution up to 45%

March 15, 2026

London, San Francisco, and Beijing are among 19 major global cities that have recorded dramatic improvements in air quality, cutting two harmful air pollutants by more than 20% over the past decade, according to a new international analysis.

The findings show that targeted clean air policies — including expanded cycling infrastructure, increased adoption of electric vehicles (EVs), and strict restrictions on high-emission vehicles — have played a key role in reducing toxic air pollution levels.

Which cities reduced pollution the most?

The report highlights standout performers in reducing fine particulate matter (PM2.5) and nitrogen dioxide (NO2) — two pollutants strongly linked to respiratory and cardiovascular disease.

• Beijing and Warsaw led global progress in lowering PM2.5 levels, cutting fine particle pollution by more than 45%.

• Amsterdam and Rotterdam recorded the largest drops in nitrogen dioxide, reducing NO2 concentrations by over 40%.

• San Francisco was the only city in the United States to reduce both PM2.5 and NO2 by more than 20%.

Out of nearly 100 cities analyzed worldwide, China and Hong Kong accounted for nine of the 19 cities achieving these significant pollution declines, while European cities made up the remainder.

How cities reduced air pollution

The research, conducted across members of the C40 and Breathe Cities networks, demonstrates that substantial air quality improvements are possible within 10 to 15 years when governments implement focused environmental strategies.

Effective interventions included:

• Rapid transition from gasoline and diesel vehicles to electric cars in China

• Expansion of protected cycle lanes in densely populated European cities

• London’s low-emission and vehicle restriction zones

• Warsaw’s move away from coal and wood-burning home heating

While the report documented major improvements, it did not isolate whether progress was driven primarily by local policies or broader national regulations.

Why reducing PM2.5 and NO2 matters for public health

Burning fossil fuels releases dangerous pollutants, including microscopic particulate matter (PM2.5) and nitrogen dioxide (NO2), both of which pose serious health risks.

PM2.5 particles are small enough to enter the bloodstream and circulate throughout the body, damaging vital organs including the brain, heart, and reproductive system. Nitrogen dioxide irritates the airways, worsens asthma, and contributes to acid rain formation.

Health experts emphasize that there is no completely safe level of PM2.5 exposure, and millions of premature deaths worldwide are linked to air pollution each year.

Air pollution impacts people at every stage of life, from low birth weight and childhood asthma to adult heart disease, cancer, cognitive decline, and dementia. Beyond the human toll, polluted air creates economic strain through healthcare costs, lost productivity, and long-term care burdens.

A turning point for urban clean air policy

Environmental leaders say the findings challenge the widespread belief that urban air pollution is too complex or politically difficult to solve.

The data shows that bold, science-based environmental policies can reduce toxic air pollution by 20–45% in just over a decade — a shift once thought unrealistic.

Despite this progress, global air quality remains a serious concern. Recent global assessments indicate that only a handful of countries currently meet World Health Organization guidelines for PM2.5 exposure.

However, the success of these 19 cities demonstrates that with political will, clean transportation, and fossil fuel reduction strategies, meaningful air quality improvements are achievable.