Lok and colleagues studied data collected by the Ozone Monitoring Instrument on NASA’s Aura satellite, which measures NO2 throughout the atmosphere in the afternoon around the world. Next they used an air quality computer model to derive from the satellite data the annual mean concentration of the gas near the ground in some of the Northern Hemisphere’s major polluting regions, excluding hot spots such as power plants that could skew the urban relationship. By overlaying pollution concentration with population density data, the researchers could examine the relationship.
Results across the different regions showed divergent NO2 surface

concentrations in urban areas of 1 million people: 0.98 parts per billion (U.S.), 1.33 ppb (Europe), 0.68 ppb (China) and 0.23 ppb (India). The same regions saw various degrees of pollution increases in cities with population of 10 million people: 2.55 ppb (U.S.), 3.86 ppb (Europe), 3.13 ppb (China) and 0.53 ppb (India).

by: Jamell O