Dense Smog Over China (image) NASA/Goddard Space Flight Center Share Print E-Mail Caption Dense smog, comprised of various pollutants, settled over the North China Plain on Feb. 20, 2011. Scientists have calculated the relationship between pollution and urban population. Image Credit: Credit NASA Goddard's MODIS Rapid Response Team Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.