Air traffic restrictions are in place at several UK airports due to severe fog, the country's main air traffic control (ATC) provider Nats said on Friday, throwing the travel plans of thousands of passengers into disarray. The restrictions, which have been put in place to ensure the safety of all flights, have resulted in numerous flight delays and cancellations, with some airlines warning of disruptions to their schedules. The worst affected airports are those in the southern and eastern parts of the country, where the fog has been particularly dense. Passengers are being advised to check with their airlines for the latest information on their flights before heading to the airport. The Met Office has issued a warning for fog, which is expected to last throughout the day, with visibility reduced to less than 100 meters in some areas. The severe weather conditions have also affected road travel, with many roads becoming treacherous due to the reduced visibility. Motorists are being advised to drive slowly and with caution, and to leave plenty of space between themselves and other vehicles. The air traffic restrictions are likely to remain in place until the fog clears, which is expected to be sometime later today. In the meantime, passengers are being advised to stay up to date with the latest information on their flights, and to plan their journeys accordingly. The UK's aviation industry is no stranger to disruptions caused by bad weather, and the current fog-related delays are just the latest in a long line of such incidents. However, with the country's airports and airlines working hard to minimize the impact of the disruptions, it is hoped that normal service will be resumed as soon as possible.