People don face masks as worst smog hits Moscow

This image, provided by NASA/MODIS Rapid Response, shows fires and thick smoke, that blanket a swath of Russia, in three consecutive overpasses on NASA's Terra satellite for MODIS, August 4, 2010. [Photo/Agencies]

Russia's President Dmitry Medvedev (C) visits ambulance service station number 26 in Moscow, August 6, 2010. [Photo/Agencies]