A spokesperson for Crossrail has told ITV London that the worker who has died was spraying concrete when a piece of concrete from the ceiling fell and hit him.
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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.