With just two days to go before the closing ceremony on Sunday evening in the Olympic stadium in London, the increase in air pollution is unlikely to cause any problems to athletes or spectators as it is a rise to a 'moderate' level of 5 on the 10-point scale.

The latest air pollution forecast from the British Department for Environment, Food and Rural Affairs (DEFRA) said, "On Sunday there is expected to be some northern European air reaching the UK, but it is forecast to be accompanied by showers."

The statement continued, "Pollution levels are therefore unlikely to increase above moderate levels across London and the south-east."

Dr Gary Fuller, a senior lecturer in air pollution measurement at the Environmental Research Group at King's College London, told Xinhua on Friday afternoon, "London can experience summertime smog when air circulates around over south-east England and the near Continent, which is just the sort of weather that we are starting to experience at the moment."

Dr Fuller said the pollution levels were "certainly not unusual" for this time of the year.

The Defra forecast predicted that pollution levels would fall back to low immediately after Sunday, as a new weather front arrived.

Weather forecasters also predicted some showers for Sunday, and Britain's national weather bureau, the Met Office, predicted the temperature would be about 21 degrees celsius in the evening.

Met Office forecaster Aidan McGivern said, "The high pressure that has brought the fine conditions is starting to slip away, and by Sunday is edging towards Scandinavia and that allows a chance of showers to extend further north and east, perhaps affecting London."

In the afternoon of the closing ceremony there is a chance of showers, but the Met Office predicts this will have lessened by the time of the closing ceremony at 9pm.