Olympic Ambassadors will be back on the streets of London today. Volunteers will be in "pods" at St Pancras International Station to welcome tourists arriving on the Eurostar.
It's the first of a series of pilots to test the project. There are 55 volunteers taking part.
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A number of people were treated at the scene at Oxford Circus by paramedics for coughing and lack of breath.
If temperatures stay high in the same spots for three consecutive days, the Met Office deems it a heatwave.
Some posts also linked to false press releases calling for the release of drill artist Digga D.