Boris Johnson and Lord Coe have been questioned about what lessons can be learned from the Olympics.
The Mayor and the London 2012 Chairman were facing questions from the London Assembly.
Toby Sadler reports.
More top news
Industrial vacuum cleaners and magnetic wands will be used each night during the summer to remove metal particles, dust, oil and grease.
Detective Superintendent Fiona McCormack said the Hotpoint FF175BP model had not been subject to any product recall.
Security for this year's event on July 8 has been reviewed following a spate of terror attacks in the capital.