Christchurch people are being warned to wear face masks to avoid breathing in earthquake debris dust that is expected to be blown across the city today in winds of up to 70km/hr.
They are also being warned not to swim in the sea, which is contaminated with raw sewage, and to continue boiling water as it remains unsafe to drink.
The health warnings heap more misery on a city battling to come to terms with the devastation of the 6.3 earthquake which has so far claimed 155 lives and left dozens of others missing.
Police believe the death toll could reach 240 but say it might not be possible to recover all of the bodies from among the ruins.
One week after the quake, most of the sites inside the city's cordon remain untouched - bikes are locked to street lights, dented and bruised cars sit under a scattering of bricks.
But at the three main sites where many of the victims died - the CTV and PGC buildings and the Christchurch Cathedral - the landscape is slowly changing as unstable buildings are deconstructed, block by block.
At the CTV building, the mound of rubble at the base has mostly disappeared.
But at the cathedral, the rubble is increasing as teams work to remove the leftovers of what fell within the tower when the spire crumbled.
Outside the city centre authorities are still going door to door, assessing the safety of damaged homes.
Of the 12,250 inspections completed by mid yesterday, 1444 have been deemed too dangerous for residents to remain in.
Many have now fled the city instead.
Police estimate up to 5000 residents have gone to Timaru where a large number of children have been temporarily enrolled in local schools.
In Christchurch City, all early childhood centres, schools and tertiary institutions have been closed until further notice.
Canterbury University has also cancelled all graduation ceremonies scheduled for next month in an attempt to take pressure off the city's infrastructure.
Meanwhile, the owners of the CTV building, in which up to 120 people are believed to have been killed, are welcoming a Government inquiry into why it collapsed.
A spokesman for the two South Island families that owned the 20-year-old six-storey building said they were "absolutely devastated and distraught" over the collapse.
Spokesman Ken Jones, of White Fox Jones law firm, said the families could not make any detailed statement because of the impending inquiry.
However they wanted to offer "their most sincere condolences" to the families of those who lost loved ones and to those who were injured.
"They wish to assure everybody they will co-operate to the fullest with the inquiry into the collapse of this modern building."
"This includes the provision of all engineers' and other reports commissioned and acted on since the September 4, 2010, earthquake."
Mr Jones said the building was inspected by the Christchurch City Council after the earthquake in September last year and deemed safe for occupation.
The property manager had commissioned a detailed structural engineers' report that recommended work to repair superficial damage which was underway at the time of the building's collapse.