Napier businesses are being advised to damp down dust from the flood until it's cleaned up

Some are complaining about the lingering drying silt, more than a week after floodwaters passed through the CBD and Napier Hill.

Hawke's Bay District Health Board says the sludge probably contained harmful germs, which could've survived drying.

Medical Officer of Health Dr Nick Jones says inhaling the dust could cause infections and fine particles could cause respiratory problems.

The City Council says staff and contractors are due to clean lower Emerson Street today - and clean up will continue elsewhere tomorrow, including Marine Parade.