Cleaner air and prosperity can go hand in hand

Using data from Europe’s Copernicus Sentinel-5P satellite mission together with information on gross domestic product (GDP), researchers have found that many of the world’s largest cities are now growing economically while reducing their emissions of the pollutant nitrogen dioxide.

The study, led by Norway’s NILU research institute and published recently in Nature Cities, analysed 2475 major urban areas around the world and found that almost 80% of them are achieving higher levels of prosperity alongside cleaner air.

At the heart of the research is Sentinel-5P, whose advanced atmospheric monitoring capabilities provide a unique global view of air quality.

Scientists used measurements of atmospheric nitrogen dioxide collected by Sentinel-5P between January 2019 and December 2024 and compared these data with information on GDP.

Because nitrogen dioxide is primarily produced through combustion processes vehicles, power plants and industrial facilities, it serves as a valuable indicator of fossil-fuel use.

While nitrogen dioxide is not considered a greenhouse gas, it is a harmful air pollutant. It can irritate the lungs, worsen asthma and other respiratory diseases, increase the risk of heart and lung problems, and contribute to premature deaths.

It also plays a major role in the formation of smog, ground-level ozone and fine particulate matter, which further degrade air quality and harm human health.

In addition, it can damage ecosystems through acid rain and nitrogen deposition, reduce crop yields, and can contribute indirectly to climate change.

By combining Sentinel-5P observations with local GDP-per-capita data, researchers were able to track how economic growth and fossil-fuel dependence evolved over time.

The satellite’s consistent global coverage enabled them to compare thousands of cities, revealing a widespread shift towards cleaner growth.

The findings indicate that almost 2000 out of the 2475 selected cities worldwide have implemented green policies that have generated economic prosperity while reducing dependencies on fossil fuels.

The trend is particularly evident in China, which accounted for 719 cities in the cleaner-and-richer category, including Beijing, Shanghai and Chengdu. Researchers attribute this progress to measures such as stricter emissions standards, electrification of public transport and the relocation of polluting industries.

Similar patterns were observed across Europe, where cities including Paris, Berlin, Rome and Amsterdam have benefited from low-emission zones and clean-energy policies.

These cities demonstrate that economic development no longer has to come at the expense of air quality.

NILU’s Daniel Moran and co-author of the study, 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.”

However, rapidly growing urban areas in parts of South Asia and the Middle East continue to show increasing dependence on fossil fuels. This suggests that economic expansion in these regions remains closely tied to combustion-based energy systems.

For example, 390 cities matched trends of economic growth, but with increased use of fossil fuels – including Moscow, Tashkent, Izmir, Riyadh and Abu Dhabi.

The study notes key uncertainties, including uneven economic data quality between countries, a study boundary that does not consider how cities’ total emissions footprints may be growing due to imports from global supply chains, and the relatively short six-year timeframe, which also covers the disruptions of the COVID-19 pandemic.

The authors also note that changes in the air pollutant nitrogen dioxide do not necessarily reflect a change in carbon dioxide or other greenhouse gases.

Despite these constraints, it offers a scalable, satellite-based framework that can be updated regularly, providing a powerful new tool for tracking urban sustainability transitions and informing policy.

The value of Sentinel-5P is clearly highlighted in the study as a powerful tool for monitoring real-world environmental change. By providing objective, global-scale measurements of air pollution, the satellite is helping researchers and policymakers track the effectiveness of green policies and identify pathways to cleaner economic growth.

The recently-launched Sentinel-4 and Sentinel-5 missions are taking air quality and atmospheric composition monitoring into the future.

From geostationary orbit, Sentinel-4 delivers data every hour, providing information on a wide range of trace gases and pollutants to forecast and monitor air quality over Europe, while Sentinel-5 in polar orbit (like Sentinel-5P) provides global data to support science, forecasts and public health alerts for air pollution, UV radiation, greenhouse gases and climate research.

ESA Atmospheric Composition Applications Scientist, Antony Delavois, noted, “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.”

Note: the study actually measured 5435 cities in total, but 2919 of them showed no significant change in their amount of nitrogen dioxide, so were excluded from further analyses. Forty-one were also removed because of unreliable GDP data.

More detail on the nitrogen dioxide trend from Sentinel-5P can also found in this recent paper: Tracking the path to cleaner cities using global NO2 monitoring from space.