Locals say Vladimir Putin 'cleaned the air' in Kransnoyarsk on his visit to the city

Krasnoyarsk has the reputation of a polluted city with fumes from local enterprises clinging to the valley of the Yenisei River. This is known locally as Black Sky Mode, because the smog blots out the sun.

Yet today residents reported a marked improvement, coinciding with a visit by President Putin to chair a session on preparations for the 2019 Winter Universiade to be held in that city.

The reason? Social media observers are in no doubt. 

They believe local officials demanded that enterprises cut emissions in the recent days so that the president would not experience any pollution during his stay. 

But bloggers warn that residents will suffer once Putin returns to Moscow. Viks7228 commented: 'It is clear that a telegram was sent and for two weeks all enterprises were advised to decrease emissions to zero. So the sky became clear. And after he leaves they will immediately raise [emissions] 300%. And the black sky will be back again.'

Viktoria wrote: 'It's a kind of magic! This means they can push Thermal power station and KRAZ (Krasnoyarsk aluminium plant), but obviously one hand washes the other and when the president leaves our city we will have 'Black Sky Mode' again.'

She suspected regional governor Viktor Tolokonsky for behind behind the alleged move. Vladimir Smirnov observed: 'Look the pollution has stopped, so the sky is clean.' 

The governor has indicated that weak wind is the cause of pollution. He has previously said: 'The wind will blow and all will be normal'. 

Later, in July 2016, his wife Natalia wrote in her Instagram 'When the thoughts in your head are clean, polluted air is not dangerous. I can teach you as a doctor.'

Ahead of the Putin visit, local media NGS24 wrote on Vkontakte social media: 'The air became clear in Krasnoyarsk, and thanks to Putin for this.' The wind 'follows the word of our governor - and blows.'

Startling pictures show conditions in Krasnoyarsk during Black Sky Mode, with locals claiming conditions are dangerous for the health of residents, especially children.

However, comparative reports do not provide evidence that the city is by any means the most polluted.

Putin arrived in Krasnoyarsk from Bishkek, Kyrgyzstan,final stopover on a Central Asian tour, in which the president also visited Almaty in Kazakhstan and  Dushanbe in Tajikistan. 

The trip was timed to mark the 25th anniversary of Russia's diplomatic relations with ex-Soviet states Kazakhstan, Tajikistan and Kyrgyzstan.

Putin used his visit to Krasnoyarsk to deny allegations of a state-sponsored sports doping programme in Russia. The claims were made by a World Anti-Doping Agency's (WADA) commission, and used by Western countries to attack Moscow. 

'I want to emphasize once again - we have always said this - there has never been, there is no, and I hope there never will be a state support system for doping in Russia,' Putin said. 'On the contrary, there will only be a fight against doping.'

Putin is closely involved in planning for the Winter Universiade 2019 in Russia's Krasnoyarsk.