Satellites offer an unprecedented opportunity to evaluate patterns and trends in air pollution, especially in regions with few or no ground-based monitors. We evaluate the 100 most populous cities worldwide, comparing nitrogen dioxide (NO2) vertical column densities from the Aura satellite to population, gross urban product (GUP), and emissions estimates. We find a positive relationship between GUP and NO2 for 38 of the 56 low-income cities, where NO2 increases with GUP, and a negative relationship for the 7 high-income cities, where NO2 decreases with GUP. This trend is consistent with the environmental Kuznets curve model. However, we found the GUP of 36 cities in the middle range of incomes did not display any consistent relationship with NO2. This partial Kuznets curve relationship arises across the 2005 to 2011 years of our study period, where specific cities show a positive or negative trend in NO2 with GUP growth over time. We analyze a global emissions inventory to compare the relationship between GUP per capita and pollution, which shows a similar relationship. The difference between observed NO2 and the emissions inventory could be due to atmospheric processes or could be due to city-specific changes in energy that are not well captured in the inventory.