Plane schedules disrupted, residents warned to stay indoors, sailors had to use GPS to get back to land because of thick smoke fumes from raging forest fires.
Krasnoyarsk's skies have been black since the start of the New Year, with locals complaining of 'chemical smell', lack of oxygen.
Krasnoyarsk and Novosibirsk suffering smoke pollution and infernos rage in forests after hot, dry weather.
Roads blocked, planes diverted due to low visibility, schools shut, people advised to stay home.
Flights late on Thursday and on Friday suffered disruption due to smog caused by blazes in dry woodland made vulnerable by the current heat wave.
Premier Dmitry Medvedev warned it will take two to three weeks to extinguish the fires raging across Siberia.
Ecology groups warn that the extent of fires in forests and taiga has been misreported by up to 159 times compared with satellite evidence of the grim facts.