A new report from Breathe Cities documents substantial improvements in urban air quality across 19 major cities worldwide. The analysis, covering data from nearly 100 cities between 2010 and 2024, shows that these locations achieved reductions of more than 20% in both fine particulate matter (PM2.5) and nitrogen dioxide (NO2). Some cities recorded even steeper declines approaching 45%.
London and San Francisco each recorded reductions exceeding 20% for both pollutants, while Beijing and Warsaw achieved standout results with PM2.5 decreases of more than 45%. Nine of the 19 leading cities are located in China and Hong Kong, with the remainder primarily in Europe. The report underscores that meaningful progress is attainable even in densely populated and rapidly developing urban environments.
Success in these cities stems from practical policy interventions such as expanded cycling infrastructure, accelerated electric vehicle adoption, vehicle emission restrictions, and shifts away from polluting domestic heating fuels. The data demonstrate that coordinated actions can deliver measurable gains in just over a decade.
For academic researchers and laboratory scientists studying environmental exposure, epidemiology, and urban health impacts, these findings provide robust real-world evidence to refine models and evaluate intervention outcomes. Looking ahead, the documented achievements could guide targeted studies and accelerate evidence-based strategies to further improve air quality toward WHO guidelines in cities worldwide.
Click here for the Japanese version.