Poor air quality linked to smoke from bushfires has increased the number of ambulance calls for respiratory problems, as well as demand of respiratory masks.

As most of Victoria woke up on Monday to a thick layer of smoke covering the sky, ambulances across the state answered an increase in the number of call-outs for respiratory issues.

Hazardous air quality due to smoke from fires in East Gippsland and NSW affected the eastern and north east parts of the state, as well as Melbourne and Geelong.

Very poor air quality conditions were forecast to cause breathing problems like coughing or shortness of breath on Monday.

"Across Victoria, about 60 more people than usual required an ambulance reporting breathing problems," a Victorian Department of Health and Human Services spokesman said.

Ambulance Victoria said paramedics had coped well with the number of extra call-outs.

This smoky weather also saw an increase in the demand for respirator masks statewide.

An Officeworks spokeswoman confirmed that although they're not running out of masks, there had been high demand across the country, in particular, in areas impacted by, or near the bushfires.

Hardware chain Bunnings confirmed they had limited stock across their Victorian stores, after initial reports suggested all P2 masks had sold out statewide.

"We are seeing increased customer demand across our Victorian stores and stock levels are changing quickly," Bunnings Regional Operations Manager Sally Powell said.

"We apologise if customers are unable to get what they need immediately - we are working to get stock to the relevant stores as quickly as possible."

The Bureau of Meteorology reported that visibility around the Melbourne area was down to 1.5 kilometres, and forecast southerly winds to improve air quality on Tuesday.

The smoky conditions, however, could continue until Sunday.

Easterly winds are expected to bring back dust on the weekend once a westerly wind current clears the air on Friday.