The London Aquatics Centre which housed the diving and swimming events during the London Olympics will open to the public from 9am.
But people are being advised to book their visit online due to concerns that there maybe significant queues to get into the venue.
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Paramedics were on standby outside the police cordon as armed officers stood by the property.
A team of researchers has taken samples from the ten busiest London Underground lines to work out which are the dirtiest.
The action comes on top of an emergency timetable which has seen hundreds of trains a day being axed.