Moscow , Russia ( CNN ) -- The Moscow skyline of the Kremlin and St . Basil 's Cathedral vanished Friday as a blanket of thick , noxious smoke shrouded the metropolis , leaving many of the city 's 10 million residents with sore throats and burning eyes . On Friday , Russian President Dmitry Medvedev visited a Moscow ambulance station , accompanied by top health officials . He was told that the number of emergency calls has increased by about 10 percent lately , related to the heat and smog . The acrid smoke , from thousands of square miles of wildfires , drove carbon monoxide levels in Moscow five times higher than what is considered safe , the Russian Health Ministry said . Residents were encouraged to stay indoors . Many who did not could be seen wearing masks as they walked outdoors . In interviews with the state-run RIA Novosti news agency , health officials likened the pollution levels to smoking several packs of cigarettes a day . Some flights to Moscow were diverted Friday because or poor visibility . The Russian Ministry for Health and Social Development reported Friday that 52 people have died as a result of the extensive fires in central Russia . Another 72 people needed treatment , 43 of whom remain hospitalized , it said . Fires were still burning Friday in 22 of the country 's 83 regions . Tens of thousands of firefighters have been deployed to extinguish nearly 600 raging wildfires covering 500,000 acres , among the worst ever . The record heat wave gripping the country showed no signs of abating Friday . Temperatures climbed to 37 degrees Celsius ( 98 degrees Fahrenheit ) in Moscow and hit 41 degrees Celsius ( nearly 106 Fahrenheit ) farther to the southeast in Tambov . By Sunday , Moscow could reach 40 degrees Celsius ( 104 Fahrenheit ) , a figure never before officially recorded in the city . Percy von Lipinski , who is visiting Russia , described the sun as a `` barely visible dot of orange trying to light the sky . '' Watch Percy 's walk through smokey Moscow . `` I dared venture outside today but can tell you that it was a difficult job , '' he said in a CNN iReport . `` Tomorrow I have decided to take my chances to see if things are any better in the country side . '' CNN 's Matthew Chance and Max Tkachenko contributed to this report .
NEW : Russian president visits ambulance station . Carbon monoxide levels are dangerously high in Moscow . People are encouraged to stay indoors and wear masks . There are no signs of the heat wave abating , and wildfires are still raging in the countryside .