Why pollution in bigger cities follows a universal mathematical pattern

Researchers combined ground monitors and satellite data across Europe to find that nitrogen dioxide pollution scales predictably with city population and distance from the city center. Pollution concentration increases as city size to the 0.14–0.22 power and decreases as distance to the −0.12–−0.18 power—the same relationship holds whether measured on the ground or from space. This unified pattern lets planners estimate how urban expansion affects total air pollution and per-capita exposure.