Thick fog causes travel disruption in London

• Westminster City Council has a stock of 1,500 tonnes of salt to use between now and the end of March
• So far this year Westminster has used zero tonnes of salt on the roads, as the road surface temperature has never dropped below freezing

• By 12th December 2012, Westminster Council had already used 65 tonnes of salt on 6 separate nights
• By 12th December 2010, we had used 242 tonnes of salt

Proof this year's winter is milder than last. Salt used on roads in Surrey by 11th Dec this year: 950 tonnes. In 2012 it was 3,100 tonnes.

The current weather conditions have led to a significant rise in smog levels around London. Parts of east London have been recorded at 'very high'.

Take a look at the figures in full from Defra here.

Hundreds of passengers are still facing delays at Heathrow because of today's foggy weather. The airport is warning of delays and cancellations tonight, and is advising all passengers to check their flight status.

Flying high above London's fog today was the Met Police helicopter. The team on board took these stunning pictures of Docklands, and The O2 which is only just about visible.

Read more: Arsenal's stadium glowing beneath the mist and fog

Thick fog has caused delays for thousands air passengers. Poor visibility led to 40 flights being cancelled at Heathrow airport. At London City Airport in Docklands nearly every early-morning service was either delayed or cancelled.