Civil Defence is to distribute face masks to the people of Christchurch.
Last week's earthquake brought an estimated 200,000 tonnes of silt to the surface, of which almost half has been cleared away.
However gusty nor-westerly winds have been drying the silt and kicking up clouds of dust.
Christchurch mayor Bob Parker is urging residents to wear face masks, which he says the Student Volunteer Army will help distribute.
Although he says the dust is not thought to be contaminated, he advises anyone with a respiratory condition to wear a mask.
It is estimated that 120,000 tonnes of silt has been cleared away.
Contracting company Fulton Hogan has collected the majority of the material from roadsides, clearing 214 streets.
Chief executive Bill Perry said that as of Wednesday the company had removed 98,000 tonnes of the silt.
Some 600 farmers were on the streets of Christchurch on Wednesday, helping clear away the material.
The 'Student Army' volunteers is also helping in the suburbs.
The silt is being taken to Burwood landfill.