Health authorities are asking people to evacuate their homes as dense smoke blankets Hobart from bushfires burning in Tasmania.

State Public Health Director Mark Veitch issued a statement warning smoke levels at Cygnet and surrounding areas could can cause serious health issues.

“Bushfire smoke is harmful and can trigger fatal health conditions,” Dr Veitch said on Thursday.

“Acting to reduce your exposure to smoke will reduce your chances of becoming seriously ill.”

The health conditions most affected by smoke include heart and lung diseases, including asthma and emphysema, and other chronic diseases such as diabetes.

People aged over 65, children aged five and under and pregnant women are also at risk, he said.

“Public Health Services strongly advises anyone in the Cygnet and surrounding areas who is vulnerable to smoke to leave the area to minimise their exposure,” Dr Veitch said.

You risk serious health harm by staying in these conditions.

The Kingborough Sports Centre in Kingston View Drive, Kingston is available as a smoke refuge and people planning to stay overnight should bring bedding, including a camp stretcher or mattress where possible, medications, phones and chargers and spare clothes.

A bus leaving from 14 Mary Street, Cygnet, at 10am and 2pm will be provided today to help people to the refuge if they are unable to access their own transport.

Hundreds of firefighters will again take their positions to battle dozens of fires scorching Tasmania as winds are expected to put more towns in the firing line.

Twelve emergency warnings are in place on Thursday for two major blazes.

The Riveaux Road fire, southwest of Hobart, is threatening numerous communities in the Huon Valley and throwing smoke across the state capital.

Bureau of Meteorology forecasts a cool change overnight is due to bring winds which will impact the fire fronts on Thursday.

Tasmania Fire Service chief officer Chris Arnol warns the Huon Valley fires are getting near urban areas, and could throw embers up to one kilometre ahead.

Communities in the state’s central plateau are at risk from the Great Pine Tier fire.

The efforts came after a week-long effort to protect a century-old trapper’s hut in the state’s southwest, known as Churchill’s Hut, failed on Wednesday.