Hundreds of paramedics, firefighters and police are taking part in a simulation in the port of Dover.
Crews will be cleaning up a simulated chemical spill from a lorry which has accidentally dropped its hazardous cargo.
Officers are keen to stress that this is an exercise so residents should not be alarmed if they hear sirens in the area.
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Largely dry with cloud and some sunny spells this afternoon with light winds.
Dry with sunny spells and light winds.
Union boss says he "deeply regrets" the disruption to people's travel plans after several days of talks failed to break the deadlock.