South Wales Fire and Rescue put out the blaze at Alexandra Docks after 20,000 tonnes of wood caught alight.
Natural Resources Wales (NRW) said it may continue to smoulder for "weeks".
It said it had served an enforcement notice on the operators last month to tackle the stockpile and reduce the risk of fire.
Ashley Lansdown, of NRW, said: "Health officials have said air quality monitoring data does not show any cause for public health concern.
"Additionally, the weather forecast is due for a change of wind direction away from areas that have been affected in the last couple of days meaning people can expect to have respite from the odours."
Wood chip piles at a dockyard in Newport are still smouldering after a fire broke out on Saturday, environment officials have said.