Twenty one year old Naomi Oni claims to have suffered burns and lost her hair and eyelashes after the chemical was thrown at her in Dagenham last December.
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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.