A wind storm which struck the city today meant dust and debris was being whipped around the city, Superintendent Dave Cliff said.
"A lot of dust, debris, and in some cases corrugated iron, [is] blowing around the central city.
"So there's a real hazard in there."
Thousands of people have resorted to using free masks handed out to deal with the dust, which health officials could be dangerous to people with asthma and respiratory illness.
Water would be sprayed on the streets to try and prevent this, Mayor Bob Parker said.
Today about 400 family members of the dead got their first chance to visit the various sites where their loved ones died after police put on a fleet of buses.
"It was a very emotional time for the families and it had been the first opportunity they had to see first hand and the extent of the devastation, and the mood was definitely sombre and very emotional for them," Mr Cliff said.
Police announced three more names of those deceased earlier today, they were -
Jayden Andrews-Howland, 15, from Aranui, Christchurch,
Paul Clarence Dunlop, 67, from Rolleston, Christchurch,
Andrew Stephen Cochrane, 43, from Bromley, Christchurch.
Meanwhile, today five journalists had their media accreditation taken off them for breaching the central city cordons, Civil Defence controller Steve Brazier said.
One Japanese journalist had his accreditation revoked after he shouldered Superintendent Dave Cliff this morning.
