A study led by the NILU research institute and published in the journal Nature Cities found that approximately 80 percent of 2,475 major urban areas worldwide achieved economic growth alongside reduced nitrogen dioxide emissions. Researchers analyzed atmospheric nitrogen dioxide levels across these urban areas, comparing measurements with regional gross domestic product data from January 2019 to December 2024.
The study identified nearly 2,000 cities that demonstrated economic expansion while decreasing fossil fuel dependence. China accounted for 719 cities that recorded economic growth accompanied by reductions in atmospheric nitrogen dioxide. Study authors attributed air quality improvements in Chinese urban areas to stricter emissions standards, public transport electrification, and industrial relocation policies.
European cities including Paris, Berlin, Rome, and Amsterdam also recorded economic growth and measurable improvements in local air quality. Municipal governments in these cities implemented low-emission zones and clean-energy initiatives. Daniel Moran, a NILU researcher, said, "It is encouraging to see green growth in action, especially since we know that cities have the same power, and often much more willingness than national politicians, to go fossil-free."
Researchers used atmospheric data collected by the Copernicus Sentinel-5P satellite mission for their analysis. The six-year research period included data gathered during the COVID-19 pandemic. Nitrogen dioxide is primarily generated through combustion processes in vehicles, power plants, and industrial facilities. Exposure to nitrogen dioxide can irritate the lungs and worsen asthma and respiratory conditions; it also contributes to the atmospheric formation of smog, ground-level ozone, and fine particulate matter.
The study also documented 390 cities that experienced economic growth concurrently with increased nitrogen dioxide emissions. Urban areas exhibiting concurrent economic growth and increased fossil fuel combustion include Moscow, Tashkent, Izmir, Riyadh, and Abu Dhabi. Researchers initially measured nitrogen dioxide levels in 5,435 cities, excluding 2,919 locations that showed no measurable emission changes. Forty-one additional cities were removed from the final dataset due to unreliable gross domestic product records. The study identified uneven economic data quality between different countries as a methodological limitation and noted that the analysis does not account for greenhouse gas concentrations generated by global supply chain imports. Changes in atmospheric nitrogen dioxide levels do not necessarily indicate corresponding fluctuations in carbon dioxide concentrations, as nitrogen dioxide is not classified as a greenhouse gas.
Antony Delavois, an atmospheric composition scientist, said, "This study is promising because it shows that, in many cities, economic growth and cleaner air can increasingly go hand in hand. Satellite missions such as Sentinel-5P provide a consistent global picture of how air pollution is changing, helping researchers, citizens and policymakers track progress and better understand the impact of environmental policies."