Israeli scientists have tracked pollution trends for 189 megacities, including New York City, Tokyo and Mumbai, using data collected by three of NASA’s high-tech aerosol monitoring satellites.
Called MODIS-Terra, MODIS-Aqua, and MISR, the satellites were launched by NASA from 2000 through 2002. Their combined data constitute an accurate survey of aerosol concentrations a few hundred metres above the Earth.
Fifty-eight of these megacities have populations exceeding five million. The thickest layers of global smog-caused by traffic, industry, and natural minerals, among other factors, are found over the world’s megacities.
Europe and Northeast and Central North America are seeing the largest decreases in aerosol concentrations overall.
Among the cleanest cities were Houston, with a 31 percent decrease over the time period; Curitiba, Brazil, with a 26 percent decrease; and Stockholm, Sweden, with a 23 percent decrease.IANS