In the morning, the city looks as if it's been covered in grey film: distant buildings are blurred, and there's a smell of burning in the air. It isn't fog, it's smog, and on still days it can hang over a city for days on end. We look at which methods of protection work and which merely reassure.

In summer 2026, residents of Krasnoyarsk lived under "black sky" conditions time and again: the regime was declared in June, extended in July and declared again in early August, when heat of up to 35°C coincided with a complete lack of wind. In June, measurements in the Solnechny district showed a concentration of benzo[a]pyrene almost 12 times above the maximum permissible level.

But smog isn't just a problem for Krasnoyarsk: in 2026, adverse weather regimes were declared in Ufa, Sterlitamak, Salavat, Tuva and other regions. What should you do when the air outside becomes dangerous?

What a "Black Sky" Is

"Black sky" is the popular name for a regime of adverse meteorological conditions (known in Russian by the abbreviation NMU). It's declared by the weather service when the weather prevents emissions from dispersing.

During this time, industrial plants are required to cut their emissions by 15–60%, depending on the level of danger, or to shut down some of their production altogether.

The regime itself doesn't mean the air is already dirty. It's a warning: the weather is such that pollution will build up. After that, everything depends on how many factories, boiler houses, cars and private houses with stove heating there are in the city.

Why Smog Hangs Over a City

The main culprit is a lack of wind. Pavel Gudovsky, chairman of the Chamber of Environmental Organisations of the Civic Assembly of Krasnoyarsk Krai, explains that if the forecast promises winds below 2 metres per second, exceedances are practically guaranteed.

The second factor is temperature inversion. Normally, the air near the ground is warmer than the air above, so it rises, carrying emissions away with it. But during an inversion, a layer of warmer air sits over the city and acts like a lid.

Everything released by chimneys and car exhausts stays in the lower layer, where we breathe.

Cities in basins, like Krasnoyarsk, suffer most, as do places with lots of coal-fired boiler houses. In Siberia, inversions are especially common during frosty anticyclones in winter, while in summer, smog is created by heat and still air.

What Helps at Home

  • Close the windows at peak times

Pollution levels are usually highest in the morning, so specialists advise against airing rooms then. But you shouldn't suffocate in stuffy air either: in extreme heat, when the temperature in the flat reaches 35°C, not airing it is harmful to health in itself. A sensible compromise is to air rooms briefly, at times when the wind picks up.

  • Switch on an air purifier

This is the most effective way to make the air in your flat cleaner. For fine particles you need a device with a HEPA filter, and a carbon filter helps with smells and gases. It's best to put the purifier in the bedroom and keep the door closed.

  • Clean with a damp cloth

Dust that settles on floors and windowsills is stirred back up into the air by dry cleaning. A damp cloth picks it up instead of spreading it around the flat.

  • Don't add pollution yourself

On smoggy days, it's best not to cook over an open flame, smoke indoors or light candles and incense: all of this adds particles to the already dirty air.

Do Masks Work?

They do, but not just any mask. An ordinary surgical mask, a cloth mask or a scarf barely stops the fine particles that make smog dangerous: air gets in around the sides and through the fabric.

What protects against fine dust are respirators of class FFP2 (and the equivalent N95 and KN95) and FFP3. FFP2, N95 and KN95 respirators filter out at least 94–95% of fine particles, and FFP3 at least 99%, including the hardest to catch, at around 0.3 microns.

The key is for the respirator to fit snugly against your face: when you breathe in, a disposable respirator should be drawn slightly inwards.

But even a good respirator has its limits: it won't protect you from gases such as formaldehyde and hydrogen sulphide. For that you need protection with special filters: Gudovsky recommends masks with filters against formaldehyde and benzo[a]pyrene costing about 6,000 roubles. And he admits frankly that many families can't afford such protection.

What to Do Outdoors

  1. Spend less time outside. This is the main recommendation during an adverse weather regime. If you can work from home or postpone errands, it's best to do so.

  2. Skip outdoor runs and workouts. During exercise, you breathe faster and more deeply, which means you inhale more pollution. It's better to move your workout to the gym or to another day.

  3. Stay away from roads. Exhaust fumes are more concentrated near busy roads. If you can walk through courtyards or along a boulevard, choose that route.

  4. Swap contact lenses for glasses. Smog irritates the eyes more, and dust particles stay trapped under contact lenses for longer.

  5. Wash when you get home. Take a shower, rinse your nose and gargle: this washes away the dust that has settled on you.

What About Closer to Home?

Adverse weather regimes are regularly declared not only in Krasnoyarsk Krai. They're recorded in the Chelyabinsk, Kemerovo, Omsk and Novosibirsk regions, in Altai and Transbaikal Krais, and in Bashkortostan and Buryatia.

In the Irkutsk Region, adverse weather regimes are regularly declared during the heating season: frosty, windless weather and coal-fired boiler houses create smog in Irkutsk, Angarsk, Shelekhov, Bratsk and other towns.

Announcements of the regime are published by the Irkutsk Directorate for Hydrometeorology and Environmental Monitoring on its website and social media, and warnings are usually repeated by the regional and city authorities. If you live in one of these towns, it's worth subscribing to these channels so you hear about smog in advance.

How to Prepare for Smog Season

  • Buy an air purifier in advance. And don't forget to change the filters according to the instructions: a clogged filter barely cleans the air.

  • Keep a supply of FFP2 respirators at home. They'll come in handy both in smog and in smoke from wildfires, which shroud the skies over Siberia every summer.

  • Watch the wind forecast. If forecasters predict several days of calm, that's a reason to plan ahead so that you spend less time outdoors.

  • Check your window seals. Old frames let outdoor air in even when closed, so the purifier ends up working in vain.