London's blushes saved by westerly wind

London's blushes were saved by a westerly wind just days before the opening of the 2012 Games, with new reports showing the worst ozone episode for six years in the capital during the week leading up to the Olympics, which was cleared by westerly winds just before the opening ceremony.

High pressure moved over the UK on July 21st, (one week before the opening ceremony), and air began to slowly circulate over southern England and the near continent, the Guardian reported. This is one of the most densely populated areas of Europe, which prompted ground-level ozone to slowly build up due to vehicle emissions and industry.

By July 25th, ground level ozone peaked in London reaching new highs according to the UK air quality index. The high levels of air pollution threatened to engulf the capital city in smog, reaching levels that exceeded the World Health Organisation Guidelines by around 80 per cent, prompting Defra to activate its new pollution alerting system for the first time.

This level of pollution stayed until the night of July 26th, the day before the Olympic opening ceremony. The build up also affected East Anglia and the Sussex coast, where onshore breezes led to ground level ozone staying above WHO guidelines for nearly 48 hours.

In the run up to the Olympics, health experts spoke out about the potential effects London air pollution could have on the athletes. Keith Prowse, respiratory consultant and medical adviser to the British Lung Foundation, said a summer fog could lead to some athletes needing medication and experiencing chest pains, sore throats and shortness of breath.

Speaking to the Guardian, he said: "Athletes are exerting themselves to the maximum, taking in a lot of air. If that air is polluted it will inflame the air passages. It could have a significant effect on endurance events like the marathon, anything over 400-800m, even sailing."

Posted by Lauren Steadman