Planes have been diverted from airports in Moscow as smog from wildfires smothers the city.
The BBC reports haze and smoke are spreading through Moscow's streets, even seeping into the metro network. Some people are wearing face masks indoors.
Officials have urged Muscovites not to venture outdoors. Daytime temperatures in Moscow are close to 40C (104F).
Nearly 560 fires were still burning across central Russia as of Friday.
They are the worst in nearly four decades. At least 50 people are dead and thousands are homeless.
Seven regions are under a state of emergency. Nizhny Novgorod, Ryazan and Voronezh are reported to be the worst hit.
Russia has declared a temporary ban on grain exports.