Shanghai called a halt to on-the-spot tomb sweeping at all cemeteries in the city through April 5, local civil affairs authorities announced on Monday afternoon.This year's Qingming Festival, a traditional time for Chinese people to pay respects to their ancestors, falls on April 5, but sweeping season began days ago.During last year's Qingming tomb-sweeping peak season, 3.43 million people visited Shanghai's 54 cemeteries and columbariums.