Moscow 'suffocated' by smog

Carbon monoxide is double the permissible level

Asthma sufferers and pregnant women have been advised to leave Moscow because of a smog emergency caused by forest fires.

It's a thick choking smog

BBC correspondent Steve Rosenberg says the air in the city is suffocating, causing sore throats and watering eyes.

"It's almost as bad inside as it is out," he says, adding that people are wearing masks on the street and in their offices.

Visibility was reduced on Thursday to just 100 metres (300 feet) in some parts of the city, and all incoming flights were suspended at the capital's three main airports.

The smog has been troubling the city throughout the summer, the result of burning trees and peat fires in the countryside around the city.

Calm weather

It has suddenly worsened because of a change in the weather.

Cars are driving with headlights on

Moscow environmental official Nikolai Fursov said: "Starting from 0300 on Thursday all impurities - suspended particles - remained close to the ground, and absolute calm prevented their dispersion."

Carbon monoxide is at more than twice its permissible levels.

Safe levels of nitrogen oxides have also been exceeded for the first time this summer.

Officials also blame the large number of cars in the city, and smoke-producing factories.

The smog is thickest in the mornings and tends to clear as the day goes on.

Precedent

On Thursday, some cars were being driven with headlights on.

It's awful, they should do something

Muscovite

The Itar-Tass news agency says the only precedent for the situation happened 30 years ago, when peat bogs around the town of Shatura, 100 kilometres (62 miles) from the city, were also burning for most of the summer.

Doctors advise pregnant women and people with asthma and heart diseases to stay at home, if they cannot leave.

The Kremlin is barely visible across the Moskva river

They are also suggesting that children stay indoors.

Kindergartens were reported to be sealing all their windows.

In some parts of Moscow the sun itself is only just able to penetrate the thick smog blanket.

"You cannot even breathe, everything is covered in smoke. It's awful, they should do something," one middle-aged woman told RTR state television.

Rain, which could help to extinguish the fires, is not expected until the middle of the month.