Smog over large world cities is often observed due to heavy traffic, industry, natural minerals and many other factors. It is a thick layer of particles of pollutant in the atmosphere, which present a serious health risk. On-the-ground monitoring stations, however, cannot provide accurate estimates of air pollution, because their positioning is the main, often limiting, factor.
This, together with reluctance of politicians to offer accurate numbers of pollution estimates, or a complete lack of a monitoring system, prevent the establishment of a standardized approach.
Scientists from Tel Aviv University’s Department of Geophysics and Planetary Sciences are testing NASA’s high-tech satellites to see whether they can collect more accurate measurements of the pollutants. Temporal data over a period of eight years are analyzed by the graduate student Olga Shvainshteinand as well as Prof. Pinhas Alpert and Dr. Pavel Kishcha. The trend in pollutants concentration was tracked for 189 megacities with population higher than 2 million, where 58 of them had more than 5 million citizens.
The three satellites that provided the data for the study were MODIS-Terra, MODIS-Aqua, and MISR. These are aerosol-monitoring satellites launched from 2000 through 2002. They provide an accurate survey of aerosol concentrations a few hundred meters above Earth.
Currently, China, India, the Middle East and Central Africa are the leaders in pollution increase between 2002 and 2010, while the cleanest cities, on the other hand, are mainly in Europe and North America. Professor Alpert is hoping that together with his team, they will develop a method for separating natural causes of pollution from man-made one.
The scientists have published the first existing method for standardized resting of pollution levels in American Journal of Climate Change. The authors are convinced that among other applications of the method, it could be a very powerful tool for monitoring emissions as well.